Source file src/crypto/x509/x509.go

     1  // Copyright 2009 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // Package x509 implements a subset of the X.509 standard.
     6  //
     7  // It allows parsing and generating certificates, certificate signing
     8  // requests, certificate revocation lists, and encoded public and private keys.
     9  // It provides a certificate verifier, complete with a chain builder.
    10  //
    11  // The package targets the X.509 technical profile defined by the IETF (RFC
    12  // 2459/3280/5280), and as further restricted by the CA/Browser Forum Baseline
    13  // Requirements. There is minimal support for features outside of these
    14  // profiles, as the primary goal of the package is to provide compatibility
    15  // with the publicly trusted TLS certificate ecosystem and its policies and
    16  // constraints.
    17  //
    18  // On macOS and Windows, certificate verification is handled by system APIs, but
    19  // the package aims to apply consistent validation rules across operating
    20  // systems.
    21  package x509
    22  
    23  import (
    24  	"bytes"
    25  	"crypto"
    26  	"crypto/ecdh"
    27  	"crypto/ecdsa"
    28  	"crypto/ed25519"
    29  	"crypto/elliptic"
    30  	"crypto/rsa"
    31  	"crypto/sha1"
    32  	"crypto/sha256"
    33  	"crypto/x509/pkix"
    34  	"encoding/asn1"
    35  	"encoding/pem"
    36  	"errors"
    37  	"fmt"
    38  	"internal/godebug"
    39  	"io"
    40  	"math/big"
    41  	"net"
    42  	"net/url"
    43  	"strconv"
    44  	"time"
    45  	"unicode"
    46  
    47  	// Explicitly import these for their crypto.RegisterHash init side-effects.
    48  	// Keep these as blank imports, even if they're imported above.
    49  	_ "crypto/sha1"
    50  	_ "crypto/sha256"
    51  	_ "crypto/sha512"
    52  
    53  	"golang.org/x/crypto/cryptobyte"
    54  	cryptobyte_asn1 "golang.org/x/crypto/cryptobyte/asn1"
    55  )
    56  
    57  // pkixPublicKey reflects a PKIX public key structure. See SubjectPublicKeyInfo
    58  // in RFC 3280.
    59  type pkixPublicKey struct {
    60  	Algo      pkix.AlgorithmIdentifier
    61  	BitString asn1.BitString
    62  }
    63  
    64  // ParsePKIXPublicKey parses a public key in PKIX, ASN.1 DER form. The encoded
    65  // public key is a SubjectPublicKeyInfo structure (see RFC 5280, Section 4.1).
    66  //
    67  // It returns a *[rsa.PublicKey], *[dsa.PublicKey], *[ecdsa.PublicKey],
    68  // [ed25519.PublicKey] (not a pointer), or *[ecdh.PublicKey] (for X25519).
    69  // More types might be supported in the future.
    70  //
    71  // This kind of key is commonly encoded in PEM blocks of type "PUBLIC KEY".
    72  func ParsePKIXPublicKey(derBytes []byte) (pub any, err error) {
    73  	var pki publicKeyInfo
    74  	if rest, err := asn1.Unmarshal(derBytes, &pki); err != nil {
    75  		if _, err := asn1.Unmarshal(derBytes, &pkcs1PublicKey{}); err == nil {
    76  			return nil, errors.New("x509: failed to parse public key (use ParsePKCS1PublicKey instead for this key format)")
    77  		}
    78  		return nil, err
    79  	} else if len(rest) != 0 {
    80  		return nil, errors.New("x509: trailing data after ASN.1 of public-key")
    81  	}
    82  	return parsePublicKey(&pki)
    83  }
    84  
    85  func marshalPublicKey(pub any) (publicKeyBytes []byte, publicKeyAlgorithm pkix.AlgorithmIdentifier, err error) {
    86  	switch pub := pub.(type) {
    87  	case *rsa.PublicKey:
    88  		publicKeyBytes, err = asn1.Marshal(pkcs1PublicKey{
    89  			N: pub.N,
    90  			E: pub.E,
    91  		})
    92  		if err != nil {
    93  			return nil, pkix.AlgorithmIdentifier{}, err
    94  		}
    95  		publicKeyAlgorithm.Algorithm = oidPublicKeyRSA
    96  		// This is a NULL parameters value which is required by
    97  		// RFC 3279, Section 2.3.1.
    98  		publicKeyAlgorithm.Parameters = asn1.NullRawValue
    99  	case *ecdsa.PublicKey:
   100  		oid, ok := oidFromNamedCurve(pub.Curve)
   101  		if !ok {
   102  			return nil, pkix.AlgorithmIdentifier{}, errors.New("x509: unsupported elliptic curve")
   103  		}
   104  		publicKeyBytes, err = pub.Bytes()
   105  		if err != nil {
   106  			return nil, pkix.AlgorithmIdentifier{}, err
   107  		}
   108  		publicKeyAlgorithm.Algorithm = oidPublicKeyECDSA
   109  		var paramBytes []byte
   110  		paramBytes, err = asn1.Marshal(oid)
   111  		if err != nil {
   112  			return
   113  		}
   114  		publicKeyAlgorithm.Parameters.FullBytes = paramBytes
   115  	case ed25519.PublicKey:
   116  		publicKeyBytes = pub
   117  		publicKeyAlgorithm.Algorithm = oidPublicKeyEd25519
   118  	case *ecdh.PublicKey:
   119  		publicKeyBytes = pub.Bytes()
   120  		if pub.Curve() == ecdh.X25519() {
   121  			publicKeyAlgorithm.Algorithm = oidPublicKeyX25519
   122  		} else {
   123  			oid, ok := oidFromECDHCurve(pub.Curve())
   124  			if !ok {
   125  				return nil, pkix.AlgorithmIdentifier{}, errors.New("x509: unsupported elliptic curve")
   126  			}
   127  			publicKeyAlgorithm.Algorithm = oidPublicKeyECDSA
   128  			var paramBytes []byte
   129  			paramBytes, err = asn1.Marshal(oid)
   130  			if err != nil {
   131  				return
   132  			}
   133  			publicKeyAlgorithm.Parameters.FullBytes = paramBytes
   134  		}
   135  	default:
   136  		return nil, pkix.AlgorithmIdentifier{}, fmt.Errorf("x509: unsupported public key type: %T", pub)
   137  	}
   138  
   139  	return publicKeyBytes, publicKeyAlgorithm, nil
   140  }
   141  
   142  // MarshalPKIXPublicKey converts a public key to PKIX, ASN.1 DER form.
   143  // The encoded public key is a SubjectPublicKeyInfo structure
   144  // (see RFC 5280, Section 4.1).
   145  //
   146  // The following key types are currently supported: *[rsa.PublicKey],
   147  // *[ecdsa.PublicKey], [ed25519.PublicKey] (not a pointer), and *[ecdh.PublicKey].
   148  // Unsupported key types result in an error.
   149  //
   150  // This kind of key is commonly encoded in PEM blocks of type "PUBLIC KEY".
   151  func MarshalPKIXPublicKey(pub any) ([]byte, error) {
   152  	var publicKeyBytes []byte
   153  	var publicKeyAlgorithm pkix.AlgorithmIdentifier
   154  	var err error
   155  
   156  	if publicKeyBytes, publicKeyAlgorithm, err = marshalPublicKey(pub); err != nil {
   157  		return nil, err
   158  	}
   159  
   160  	pkix := pkixPublicKey{
   161  		Algo: publicKeyAlgorithm,
   162  		BitString: asn1.BitString{
   163  			Bytes:     publicKeyBytes,
   164  			BitLength: 8 * len(publicKeyBytes),
   165  		},
   166  	}
   167  
   168  	ret, _ := asn1.Marshal(pkix)
   169  	return ret, nil
   170  }
   171  
   172  // These structures reflect the ASN.1 structure of X.509 certificates.:
   173  
   174  type certificate struct {
   175  	TBSCertificate     tbsCertificate
   176  	SignatureAlgorithm pkix.AlgorithmIdentifier
   177  	SignatureValue     asn1.BitString
   178  }
   179  
   180  type tbsCertificate struct {
   181  	Raw                asn1.RawContent
   182  	Version            int `asn1:"optional,explicit,default:0,tag:0"`
   183  	SerialNumber       *big.Int
   184  	SignatureAlgorithm pkix.AlgorithmIdentifier
   185  	Issuer             asn1.RawValue
   186  	Validity           validity
   187  	Subject            asn1.RawValue
   188  	PublicKey          publicKeyInfo
   189  	UniqueId           asn1.BitString   `asn1:"optional,tag:1"`
   190  	SubjectUniqueId    asn1.BitString   `asn1:"optional,tag:2"`
   191  	Extensions         []pkix.Extension `asn1:"omitempty,optional,explicit,tag:3"`
   192  }
   193  
   194  type dsaAlgorithmParameters struct {
   195  	P, Q, G *big.Int
   196  }
   197  
   198  type validity struct {
   199  	NotBefore, NotAfter time.Time
   200  }
   201  
   202  type publicKeyInfo struct {
   203  	Raw       asn1.RawContent
   204  	Algorithm pkix.AlgorithmIdentifier
   205  	PublicKey asn1.BitString
   206  }
   207  
   208  // RFC 5280,  4.2.1.1
   209  type authKeyId struct {
   210  	Id []byte `asn1:"optional,tag:0"`
   211  }
   212  
   213  type SignatureAlgorithm int
   214  
   215  const (
   216  	UnknownSignatureAlgorithm SignatureAlgorithm = iota
   217  
   218  	MD2WithRSA  // Unsupported.
   219  	MD5WithRSA  // Only supported for signing, not verification.
   220  	SHA1WithRSA // Only supported for signing, and verification of CRLs, CSRs, and OCSP responses.
   221  	SHA256WithRSA
   222  	SHA384WithRSA
   223  	SHA512WithRSA
   224  	DSAWithSHA1   // Unsupported.
   225  	DSAWithSHA256 // Unsupported.
   226  	ECDSAWithSHA1 // Only supported for signing, and verification of CRLs, CSRs, and OCSP responses.
   227  	ECDSAWithSHA256
   228  	ECDSAWithSHA384
   229  	ECDSAWithSHA512
   230  	SHA256WithRSAPSS
   231  	SHA384WithRSAPSS
   232  	SHA512WithRSAPSS
   233  	PureEd25519
   234  )
   235  
   236  func (algo SignatureAlgorithm) isRSAPSS() bool {
   237  	for _, details := range signatureAlgorithmDetails {
   238  		if details.algo == algo {
   239  			return details.isRSAPSS
   240  		}
   241  	}
   242  	return false
   243  }
   244  
   245  func (algo SignatureAlgorithm) hashFunc() crypto.Hash {
   246  	for _, details := range signatureAlgorithmDetails {
   247  		if details.algo == algo {
   248  			return details.hash
   249  		}
   250  	}
   251  	return crypto.Hash(0)
   252  }
   253  
   254  func (algo SignatureAlgorithm) String() string {
   255  	for _, details := range signatureAlgorithmDetails {
   256  		if details.algo == algo {
   257  			return details.name
   258  		}
   259  	}
   260  	return strconv.Itoa(int(algo))
   261  }
   262  
   263  type PublicKeyAlgorithm int
   264  
   265  const (
   266  	UnknownPublicKeyAlgorithm PublicKeyAlgorithm = iota
   267  	RSA
   268  	DSA // Only supported for parsing.
   269  	ECDSA
   270  	Ed25519
   271  )
   272  
   273  var publicKeyAlgoName = [...]string{
   274  	RSA:     "RSA",
   275  	DSA:     "DSA",
   276  	ECDSA:   "ECDSA",
   277  	Ed25519: "Ed25519",
   278  }
   279  
   280  func (algo PublicKeyAlgorithm) String() string {
   281  	if 0 < algo && int(algo) < len(publicKeyAlgoName) {
   282  		return publicKeyAlgoName[algo]
   283  	}
   284  	return strconv.Itoa(int(algo))
   285  }
   286  
   287  // OIDs for signature algorithms
   288  //
   289  //	pkcs-1 OBJECT IDENTIFIER ::= {
   290  //		iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 1 }
   291  //
   292  // RFC 3279 2.2.1 RSA Signature Algorithms
   293  //
   294  //	md5WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 4 }
   295  //
   296  //	sha-1WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 5 }
   297  //
   298  //	dsaWithSha1 OBJECT IDENTIFIER ::= {
   299  //		iso(1) member-body(2) us(840) x9-57(10040) x9cm(4) 3 }
   300  //
   301  // RFC 3279 2.2.3 ECDSA Signature Algorithm
   302  //
   303  //	ecdsa-with-SHA1 OBJECT IDENTIFIER ::= {
   304  //		iso(1) member-body(2) us(840) ansi-x962(10045)
   305  //		signatures(4) ecdsa-with-SHA1(1)}
   306  //
   307  // RFC 4055 5 PKCS #1 Version 1.5
   308  //
   309  //	sha256WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 11 }
   310  //
   311  //	sha384WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 12 }
   312  //
   313  //	sha512WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 13 }
   314  //
   315  // RFC 5758 3.1 DSA Signature Algorithms
   316  //
   317  //	dsaWithSha256 OBJECT IDENTIFIER ::= {
   318  //		joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101)
   319  //		csor(3) algorithms(4) id-dsa-with-sha2(3) 2}
   320  //
   321  // RFC 5758 3.2 ECDSA Signature Algorithm
   322  //
   323  //	ecdsa-with-SHA256 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
   324  //		us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 2 }
   325  //
   326  //	ecdsa-with-SHA384 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
   327  //		us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 3 }
   328  //
   329  //	ecdsa-with-SHA512 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
   330  //		us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 4 }
   331  //
   332  // RFC 8410 3 Curve25519 and Curve448 Algorithm Identifiers
   333  //
   334  //	id-Ed25519   OBJECT IDENTIFIER ::= { 1 3 101 112 }
   335  var (
   336  	oidSignatureMD5WithRSA      = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 4}
   337  	oidSignatureSHA1WithRSA     = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 5}
   338  	oidSignatureSHA256WithRSA   = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 11}
   339  	oidSignatureSHA384WithRSA   = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 12}
   340  	oidSignatureSHA512WithRSA   = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 13}
   341  	oidSignatureRSAPSS          = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 10}
   342  	oidSignatureDSAWithSHA1     = asn1.ObjectIdentifier{1, 2, 840, 10040, 4, 3}
   343  	oidSignatureDSAWithSHA256   = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 3, 2}
   344  	oidSignatureECDSAWithSHA1   = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 1}
   345  	oidSignatureECDSAWithSHA256 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 2}
   346  	oidSignatureECDSAWithSHA384 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 3}
   347  	oidSignatureECDSAWithSHA512 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 4}
   348  	oidSignatureEd25519         = asn1.ObjectIdentifier{1, 3, 101, 112}
   349  
   350  	oidSHA256 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 1}
   351  	oidSHA384 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 2}
   352  	oidSHA512 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 3}
   353  
   354  	oidMGF1 = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 8}
   355  
   356  	// oidISOSignatureSHA1WithRSA means the same as oidSignatureSHA1WithRSA
   357  	// but it's specified by ISO. Microsoft's makecert.exe has been known
   358  	// to produce certificates with this OID.
   359  	oidISOSignatureSHA1WithRSA = asn1.ObjectIdentifier{1, 3, 14, 3, 2, 29}
   360  )
   361  
   362  var signatureAlgorithmDetails = []struct {
   363  	algo       SignatureAlgorithm
   364  	name       string
   365  	oid        asn1.ObjectIdentifier
   366  	params     asn1.RawValue
   367  	pubKeyAlgo PublicKeyAlgorithm
   368  	hash       crypto.Hash
   369  	isRSAPSS   bool
   370  }{
   371  	{MD5WithRSA, "MD5-RSA", oidSignatureMD5WithRSA, asn1.NullRawValue, RSA, crypto.MD5, false},
   372  	{SHA1WithRSA, "SHA1-RSA", oidSignatureSHA1WithRSA, asn1.NullRawValue, RSA, crypto.SHA1, false},
   373  	{SHA1WithRSA, "SHA1-RSA", oidISOSignatureSHA1WithRSA, asn1.NullRawValue, RSA, crypto.SHA1, false},
   374  	{SHA256WithRSA, "SHA256-RSA", oidSignatureSHA256WithRSA, asn1.NullRawValue, RSA, crypto.SHA256, false},
   375  	{SHA384WithRSA, "SHA384-RSA", oidSignatureSHA384WithRSA, asn1.NullRawValue, RSA, crypto.SHA384, false},
   376  	{SHA512WithRSA, "SHA512-RSA", oidSignatureSHA512WithRSA, asn1.NullRawValue, RSA, crypto.SHA512, false},
   377  	{SHA256WithRSAPSS, "SHA256-RSAPSS", oidSignatureRSAPSS, pssParametersSHA256, RSA, crypto.SHA256, true},
   378  	{SHA384WithRSAPSS, "SHA384-RSAPSS", oidSignatureRSAPSS, pssParametersSHA384, RSA, crypto.SHA384, true},
   379  	{SHA512WithRSAPSS, "SHA512-RSAPSS", oidSignatureRSAPSS, pssParametersSHA512, RSA, crypto.SHA512, true},
   380  	{DSAWithSHA1, "DSA-SHA1", oidSignatureDSAWithSHA1, emptyRawValue, DSA, crypto.SHA1, false},
   381  	{DSAWithSHA256, "DSA-SHA256", oidSignatureDSAWithSHA256, emptyRawValue, DSA, crypto.SHA256, false},
   382  	{ECDSAWithSHA1, "ECDSA-SHA1", oidSignatureECDSAWithSHA1, emptyRawValue, ECDSA, crypto.SHA1, false},
   383  	{ECDSAWithSHA256, "ECDSA-SHA256", oidSignatureECDSAWithSHA256, emptyRawValue, ECDSA, crypto.SHA256, false},
   384  	{ECDSAWithSHA384, "ECDSA-SHA384", oidSignatureECDSAWithSHA384, emptyRawValue, ECDSA, crypto.SHA384, false},
   385  	{ECDSAWithSHA512, "ECDSA-SHA512", oidSignatureECDSAWithSHA512, emptyRawValue, ECDSA, crypto.SHA512, false},
   386  	{PureEd25519, "Ed25519", oidSignatureEd25519, emptyRawValue, Ed25519, crypto.Hash(0) /* no pre-hashing */, false},
   387  }
   388  
   389  var emptyRawValue = asn1.RawValue{}
   390  
   391  // DER encoded RSA PSS parameters for the
   392  // SHA256, SHA384, and SHA512 hashes as defined in RFC 3447, Appendix A.2.3.
   393  // The parameters contain the following values:
   394  //   - hashAlgorithm contains the associated hash identifier with NULL parameters
   395  //   - maskGenAlgorithm always contains the default mgf1SHA1 identifier
   396  //   - saltLength contains the length of the associated hash
   397  //   - trailerField always contains the default trailerFieldBC value
   398  var (
   399  	pssParametersSHA256 = asn1.RawValue{FullBytes: []byte{48, 52, 160, 15, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 1, 5, 0, 161, 28, 48, 26, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 8, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 1, 5, 0, 162, 3, 2, 1, 32}}
   400  	pssParametersSHA384 = asn1.RawValue{FullBytes: []byte{48, 52, 160, 15, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 2, 5, 0, 161, 28, 48, 26, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 8, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 2, 5, 0, 162, 3, 2, 1, 48}}
   401  	pssParametersSHA512 = asn1.RawValue{FullBytes: []byte{48, 52, 160, 15, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 3, 5, 0, 161, 28, 48, 26, 6, 9, 42, 134, 72, 134, 247, 13, 1, 1, 8, 48, 13, 6, 9, 96, 134, 72, 1, 101, 3, 4, 2, 3, 5, 0, 162, 3, 2, 1, 64}}
   402  )
   403  
   404  // pssParameters reflects the parameters in an AlgorithmIdentifier that
   405  // specifies RSA PSS. See RFC 3447, Appendix A.2.3.
   406  type pssParameters struct {
   407  	// The following three fields are not marked as
   408  	// optional because the default values specify SHA-1,
   409  	// which is no longer suitable for use in signatures.
   410  	Hash         pkix.AlgorithmIdentifier `asn1:"explicit,tag:0"`
   411  	MGF          pkix.AlgorithmIdentifier `asn1:"explicit,tag:1"`
   412  	SaltLength   int                      `asn1:"explicit,tag:2"`
   413  	TrailerField int                      `asn1:"optional,explicit,tag:3,default:1"`
   414  }
   415  
   416  func getSignatureAlgorithmFromAI(ai pkix.AlgorithmIdentifier) SignatureAlgorithm {
   417  	if ai.Algorithm.Equal(oidSignatureEd25519) {
   418  		// RFC 8410, Section 3
   419  		// > For all of the OIDs, the parameters MUST be absent.
   420  		if len(ai.Parameters.FullBytes) != 0 {
   421  			return UnknownSignatureAlgorithm
   422  		}
   423  	}
   424  
   425  	if !ai.Algorithm.Equal(oidSignatureRSAPSS) {
   426  		for _, details := range signatureAlgorithmDetails {
   427  			if ai.Algorithm.Equal(details.oid) {
   428  				return details.algo
   429  			}
   430  		}
   431  		return UnknownSignatureAlgorithm
   432  	}
   433  
   434  	// RSA PSS is special because it encodes important parameters
   435  	// in the Parameters.
   436  
   437  	var params pssParameters
   438  	if _, err := asn1.Unmarshal(ai.Parameters.FullBytes, &params); err != nil {
   439  		return UnknownSignatureAlgorithm
   440  	}
   441  
   442  	var mgf1HashFunc pkix.AlgorithmIdentifier
   443  	if _, err := asn1.Unmarshal(params.MGF.Parameters.FullBytes, &mgf1HashFunc); err != nil {
   444  		return UnknownSignatureAlgorithm
   445  	}
   446  
   447  	// PSS is greatly overburdened with options. This code forces them into
   448  	// three buckets by requiring that the MGF1 hash function always match the
   449  	// message hash function (as recommended in RFC 3447, Section 8.1), that the
   450  	// salt length matches the hash length, and that the trailer field has the
   451  	// default value.
   452  	if (len(params.Hash.Parameters.FullBytes) != 0 && !bytes.Equal(params.Hash.Parameters.FullBytes, asn1.NullBytes)) ||
   453  		!params.MGF.Algorithm.Equal(oidMGF1) ||
   454  		!mgf1HashFunc.Algorithm.Equal(params.Hash.Algorithm) ||
   455  		(len(mgf1HashFunc.Parameters.FullBytes) != 0 && !bytes.Equal(mgf1HashFunc.Parameters.FullBytes, asn1.NullBytes)) ||
   456  		params.TrailerField != 1 {
   457  		return UnknownSignatureAlgorithm
   458  	}
   459  
   460  	switch {
   461  	case params.Hash.Algorithm.Equal(oidSHA256) && params.SaltLength == 32:
   462  		return SHA256WithRSAPSS
   463  	case params.Hash.Algorithm.Equal(oidSHA384) && params.SaltLength == 48:
   464  		return SHA384WithRSAPSS
   465  	case params.Hash.Algorithm.Equal(oidSHA512) && params.SaltLength == 64:
   466  		return SHA512WithRSAPSS
   467  	}
   468  
   469  	return UnknownSignatureAlgorithm
   470  }
   471  
   472  var (
   473  	// RFC 3279, 2.3 Public Key Algorithms
   474  	//
   475  	//	pkcs-1 OBJECT IDENTIFIER ::== { iso(1) member-body(2) us(840)
   476  	//		rsadsi(113549) pkcs(1) 1 }
   477  	//
   478  	// rsaEncryption OBJECT IDENTIFIER ::== { pkcs1-1 1 }
   479  	//
   480  	//	id-dsa OBJECT IDENTIFIER ::== { iso(1) member-body(2) us(840)
   481  	//		x9-57(10040) x9cm(4) 1 }
   482  	oidPublicKeyRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 1}
   483  	oidPublicKeyDSA = asn1.ObjectIdentifier{1, 2, 840, 10040, 4, 1}
   484  	// RFC 5480, 2.1.1 Unrestricted Algorithm Identifier and Parameters
   485  	//
   486  	//	id-ecPublicKey OBJECT IDENTIFIER ::= {
   487  	//		iso(1) member-body(2) us(840) ansi-X9-62(10045) keyType(2) 1 }
   488  	oidPublicKeyECDSA = asn1.ObjectIdentifier{1, 2, 840, 10045, 2, 1}
   489  	// RFC 8410, Section 3
   490  	//
   491  	//	id-X25519    OBJECT IDENTIFIER ::= { 1 3 101 110 }
   492  	//	id-Ed25519   OBJECT IDENTIFIER ::= { 1 3 101 112 }
   493  	oidPublicKeyX25519  = asn1.ObjectIdentifier{1, 3, 101, 110}
   494  	oidPublicKeyEd25519 = asn1.ObjectIdentifier{1, 3, 101, 112}
   495  )
   496  
   497  // getPublicKeyAlgorithmFromOID returns the exposed PublicKeyAlgorithm
   498  // identifier for public key types supported in certificates and CSRs. Marshal
   499  // and Parse functions may support a different set of public key types.
   500  func getPublicKeyAlgorithmFromOID(oid asn1.ObjectIdentifier) PublicKeyAlgorithm {
   501  	switch {
   502  	case oid.Equal(oidPublicKeyRSA):
   503  		return RSA
   504  	case oid.Equal(oidPublicKeyDSA):
   505  		return DSA
   506  	case oid.Equal(oidPublicKeyECDSA):
   507  		return ECDSA
   508  	case oid.Equal(oidPublicKeyEd25519):
   509  		return Ed25519
   510  	}
   511  	return UnknownPublicKeyAlgorithm
   512  }
   513  
   514  // RFC 5480, 2.1.1.1. Named Curve
   515  //
   516  //	secp224r1 OBJECT IDENTIFIER ::= {
   517  //	  iso(1) identified-organization(3) certicom(132) curve(0) 33 }
   518  //
   519  //	secp256r1 OBJECT IDENTIFIER ::= {
   520  //	  iso(1) member-body(2) us(840) ansi-X9-62(10045) curves(3)
   521  //	  prime(1) 7 }
   522  //
   523  //	secp384r1 OBJECT IDENTIFIER ::= {
   524  //	  iso(1) identified-organization(3) certicom(132) curve(0) 34 }
   525  //
   526  //	secp521r1 OBJECT IDENTIFIER ::= {
   527  //	  iso(1) identified-organization(3) certicom(132) curve(0) 35 }
   528  //
   529  // NB: secp256r1 is equivalent to prime256v1
   530  var (
   531  	oidNamedCurveP224 = asn1.ObjectIdentifier{1, 3, 132, 0, 33}
   532  	oidNamedCurveP256 = asn1.ObjectIdentifier{1, 2, 840, 10045, 3, 1, 7}
   533  	oidNamedCurveP384 = asn1.ObjectIdentifier{1, 3, 132, 0, 34}
   534  	oidNamedCurveP521 = asn1.ObjectIdentifier{1, 3, 132, 0, 35}
   535  )
   536  
   537  func namedCurveFromOID(oid asn1.ObjectIdentifier) elliptic.Curve {
   538  	switch {
   539  	case oid.Equal(oidNamedCurveP224):
   540  		return elliptic.P224()
   541  	case oid.Equal(oidNamedCurveP256):
   542  		return elliptic.P256()
   543  	case oid.Equal(oidNamedCurveP384):
   544  		return elliptic.P384()
   545  	case oid.Equal(oidNamedCurveP521):
   546  		return elliptic.P521()
   547  	}
   548  	return nil
   549  }
   550  
   551  func oidFromNamedCurve(curve elliptic.Curve) (asn1.ObjectIdentifier, bool) {
   552  	switch curve {
   553  	case elliptic.P224():
   554  		return oidNamedCurveP224, true
   555  	case elliptic.P256():
   556  		return oidNamedCurveP256, true
   557  	case elliptic.P384():
   558  		return oidNamedCurveP384, true
   559  	case elliptic.P521():
   560  		return oidNamedCurveP521, true
   561  	}
   562  
   563  	return nil, false
   564  }
   565  
   566  func oidFromECDHCurve(curve ecdh.Curve) (asn1.ObjectIdentifier, bool) {
   567  	switch curve {
   568  	case ecdh.X25519():
   569  		return oidPublicKeyX25519, true
   570  	case ecdh.P256():
   571  		return oidNamedCurveP256, true
   572  	case ecdh.P384():
   573  		return oidNamedCurveP384, true
   574  	case ecdh.P521():
   575  		return oidNamedCurveP521, true
   576  	}
   577  
   578  	return nil, false
   579  }
   580  
   581  // KeyUsage represents the set of actions that are valid for a given key. It's
   582  // a bitmap of the KeyUsage* constants.
   583  type KeyUsage int
   584  
   585  //go:generate stringer -linecomment -type=KeyUsage,ExtKeyUsage -output=x509_string.go
   586  
   587  const (
   588  	KeyUsageDigitalSignature  KeyUsage = 1 << iota // digitalSignature
   589  	KeyUsageContentCommitment                      // contentCommitment
   590  	KeyUsageKeyEncipherment                        // keyEncipherment
   591  	KeyUsageDataEncipherment                       // dataEncipherment
   592  	KeyUsageKeyAgreement                           // keyAgreement
   593  	KeyUsageCertSign                               // keyCertSign
   594  	KeyUsageCRLSign                                // cRLSign
   595  	KeyUsageEncipherOnly                           // encipherOnly
   596  	KeyUsageDecipherOnly                           // decipherOnly
   597  )
   598  
   599  // RFC 5280, 4.2.1.12  Extended Key Usage
   600  //
   601  //	anyExtendedKeyUsage OBJECT IDENTIFIER ::= { id-ce-extKeyUsage 0 }
   602  //
   603  //	id-kp OBJECT IDENTIFIER ::= { id-pkix 3 }
   604  //
   605  //	id-kp-serverAuth             OBJECT IDENTIFIER ::= { id-kp 1 }
   606  //	id-kp-clientAuth             OBJECT IDENTIFIER ::= { id-kp 2 }
   607  //	id-kp-codeSigning            OBJECT IDENTIFIER ::= { id-kp 3 }
   608  //	id-kp-emailProtection        OBJECT IDENTIFIER ::= { id-kp 4 }
   609  //	id-kp-timeStamping           OBJECT IDENTIFIER ::= { id-kp 8 }
   610  //	id-kp-OCSPSigning            OBJECT IDENTIFIER ::= { id-kp 9 }
   611  //
   612  // https://www.iana.org/assignments/smi-numbers/smi-numbers.xhtml#smi-numbers-1.3.6.1.5.5.7.3
   613  var (
   614  	oidExtKeyUsageAny                            = asn1.ObjectIdentifier{2, 5, 29, 37, 0}
   615  	oidExtKeyUsageServerAuth                     = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 1}
   616  	oidExtKeyUsageClientAuth                     = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 2}
   617  	oidExtKeyUsageCodeSigning                    = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 3}
   618  	oidExtKeyUsageEmailProtection                = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 4}
   619  	oidExtKeyUsageIPSECEndSystem                 = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 5}
   620  	oidExtKeyUsageIPSECTunnel                    = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 6}
   621  	oidExtKeyUsageIPSECUser                      = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 7}
   622  	oidExtKeyUsageTimeStamping                   = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 8}
   623  	oidExtKeyUsageOCSPSigning                    = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 9}
   624  	oidExtKeyUsageMicrosoftServerGatedCrypto     = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 10, 3, 3}
   625  	oidExtKeyUsageNetscapeServerGatedCrypto      = asn1.ObjectIdentifier{2, 16, 840, 1, 113730, 4, 1}
   626  	oidExtKeyUsageMicrosoftCommercialCodeSigning = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 2, 1, 22}
   627  	oidExtKeyUsageMicrosoftKernelCodeSigning     = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 61, 1, 1}
   628  )
   629  
   630  // ExtKeyUsage represents an extended set of actions that are valid for a given key.
   631  // Each of the ExtKeyUsage* constants define a unique action.
   632  type ExtKeyUsage int
   633  
   634  const (
   635  	ExtKeyUsageAny                            ExtKeyUsage = iota // anyExtendedKeyUsage
   636  	ExtKeyUsageServerAuth                                        // serverAuth
   637  	ExtKeyUsageClientAuth                                        // clientAuth
   638  	ExtKeyUsageCodeSigning                                       // codeSigning
   639  	ExtKeyUsageEmailProtection                                   // emailProtection
   640  	ExtKeyUsageIPSECEndSystem                                    // ipsecEndSystem
   641  	ExtKeyUsageIPSECTunnel                                       // ipsecTunnel
   642  	ExtKeyUsageIPSECUser                                         // ipsecUser
   643  	ExtKeyUsageTimeStamping                                      // timeStamping
   644  	ExtKeyUsageOCSPSigning                                       // OCSPSigning
   645  	ExtKeyUsageMicrosoftServerGatedCrypto                        // msSGC
   646  	ExtKeyUsageNetscapeServerGatedCrypto                         // nsSGC
   647  	ExtKeyUsageMicrosoftCommercialCodeSigning                    // msCodeCom
   648  	ExtKeyUsageMicrosoftKernelCodeSigning                        // msKernelCode
   649  )
   650  
   651  // extKeyUsageOIDs contains the mapping between an ExtKeyUsage and its OID.
   652  var extKeyUsageOIDs = []struct {
   653  	extKeyUsage ExtKeyUsage
   654  	oid         asn1.ObjectIdentifier
   655  }{
   656  	{ExtKeyUsageAny, oidExtKeyUsageAny},
   657  	{ExtKeyUsageServerAuth, oidExtKeyUsageServerAuth},
   658  	{ExtKeyUsageClientAuth, oidExtKeyUsageClientAuth},
   659  	{ExtKeyUsageCodeSigning, oidExtKeyUsageCodeSigning},
   660  	{ExtKeyUsageEmailProtection, oidExtKeyUsageEmailProtection},
   661  	{ExtKeyUsageIPSECEndSystem, oidExtKeyUsageIPSECEndSystem},
   662  	{ExtKeyUsageIPSECTunnel, oidExtKeyUsageIPSECTunnel},
   663  	{ExtKeyUsageIPSECUser, oidExtKeyUsageIPSECUser},
   664  	{ExtKeyUsageTimeStamping, oidExtKeyUsageTimeStamping},
   665  	{ExtKeyUsageOCSPSigning, oidExtKeyUsageOCSPSigning},
   666  	{ExtKeyUsageMicrosoftServerGatedCrypto, oidExtKeyUsageMicrosoftServerGatedCrypto},
   667  	{ExtKeyUsageNetscapeServerGatedCrypto, oidExtKeyUsageNetscapeServerGatedCrypto},
   668  	{ExtKeyUsageMicrosoftCommercialCodeSigning, oidExtKeyUsageMicrosoftCommercialCodeSigning},
   669  	{ExtKeyUsageMicrosoftKernelCodeSigning, oidExtKeyUsageMicrosoftKernelCodeSigning},
   670  }
   671  
   672  func extKeyUsageFromOID(oid asn1.ObjectIdentifier) (eku ExtKeyUsage, ok bool) {
   673  	for _, pair := range extKeyUsageOIDs {
   674  		if oid.Equal(pair.oid) {
   675  			return pair.extKeyUsage, true
   676  		}
   677  	}
   678  	return
   679  }
   680  
   681  func oidFromExtKeyUsage(eku ExtKeyUsage) (oid asn1.ObjectIdentifier, ok bool) {
   682  	for _, pair := range extKeyUsageOIDs {
   683  		if eku == pair.extKeyUsage {
   684  			return pair.oid, true
   685  		}
   686  	}
   687  	return
   688  }
   689  
   690  // OID returns the ASN.1 object identifier of the EKU.
   691  func (eku ExtKeyUsage) OID() OID {
   692  	asn1OID, ok := oidFromExtKeyUsage(eku)
   693  	if !ok {
   694  		panic("x509: internal error: known ExtKeyUsage has no OID")
   695  	}
   696  	oid, err := OIDFromASN1OID(asn1OID)
   697  	if err != nil {
   698  		panic("x509: internal error: known ExtKeyUsage has invalid OID")
   699  	}
   700  	return oid
   701  }
   702  
   703  // A Certificate represents an X.509 certificate.
   704  type Certificate struct {
   705  	Raw                     []byte // Complete ASN.1 DER content (certificate, signature algorithm and signature).
   706  	RawTBSCertificate       []byte // Certificate part of raw ASN.1 DER content.
   707  	RawSubjectPublicKeyInfo []byte // DER encoded SubjectPublicKeyInfo.
   708  	RawSubject              []byte // DER encoded Subject
   709  	RawIssuer               []byte // DER encoded Issuer
   710  
   711  	Signature          []byte
   712  	SignatureAlgorithm SignatureAlgorithm
   713  
   714  	PublicKeyAlgorithm PublicKeyAlgorithm
   715  	PublicKey          any
   716  
   717  	Version             int
   718  	SerialNumber        *big.Int
   719  	Issuer              pkix.Name
   720  	Subject             pkix.Name
   721  	NotBefore, NotAfter time.Time // Validity bounds.
   722  	KeyUsage            KeyUsage
   723  
   724  	// Extensions contains raw X.509 extensions. When parsing certificates,
   725  	// this can be used to extract non-critical extensions that are not
   726  	// parsed by this package. When marshaling certificates, the Extensions
   727  	// field is ignored, see ExtraExtensions.
   728  	Extensions []pkix.Extension
   729  
   730  	// ExtraExtensions contains extensions to be copied, raw, into any
   731  	// marshaled certificates. Values override any extensions that would
   732  	// otherwise be produced based on the other fields. The ExtraExtensions
   733  	// field is not populated when parsing certificates, see Extensions.
   734  	ExtraExtensions []pkix.Extension
   735  
   736  	// UnhandledCriticalExtensions contains a list of extension IDs that
   737  	// were not (fully) processed when parsing. Verify will fail if this
   738  	// slice is non-empty, unless verification is delegated to an OS
   739  	// library which understands all the critical extensions.
   740  	//
   741  	// Users can access these extensions using Extensions and can remove
   742  	// elements from this slice if they believe that they have been
   743  	// handled.
   744  	UnhandledCriticalExtensions []asn1.ObjectIdentifier
   745  
   746  	ExtKeyUsage        []ExtKeyUsage           // Sequence of extended key usages.
   747  	UnknownExtKeyUsage []asn1.ObjectIdentifier // Encountered extended key usages unknown to this package.
   748  
   749  	// BasicConstraintsValid indicates whether IsCA, MaxPathLen,
   750  	// and MaxPathLenZero are valid.
   751  	BasicConstraintsValid bool
   752  	IsCA                  bool
   753  
   754  	// MaxPathLen and MaxPathLenZero indicate the presence and
   755  	// value of the BasicConstraints' "pathLenConstraint".
   756  	//
   757  	// When parsing a certificate, a positive non-zero MaxPathLen
   758  	// means that the field was specified, -1 means it was unset,
   759  	// and MaxPathLenZero being true mean that the field was
   760  	// explicitly set to zero. The case of MaxPathLen==0 with MaxPathLenZero==false
   761  	// should be treated equivalent to -1 (unset).
   762  	//
   763  	// When generating a certificate, an unset pathLenConstraint
   764  	// can be requested with either MaxPathLen == -1 or using the
   765  	// zero value for both MaxPathLen and MaxPathLenZero.
   766  	MaxPathLen int
   767  	// MaxPathLenZero indicates that BasicConstraintsValid==true
   768  	// and MaxPathLen==0 should be interpreted as an actual
   769  	// maximum path length of zero. Otherwise, that combination is
   770  	// interpreted as MaxPathLen not being set.
   771  	MaxPathLenZero bool
   772  
   773  	SubjectKeyId   []byte
   774  	AuthorityKeyId []byte
   775  
   776  	// RFC 5280, 4.2.2.1 (Authority Information Access)
   777  	OCSPServer            []string
   778  	IssuingCertificateURL []string
   779  
   780  	// Subject Alternate Name values. (Note that these values may not be valid
   781  	// if invalid values were contained within a parsed certificate. For
   782  	// example, an element of DNSNames may not be a valid DNS domain name.)
   783  	DNSNames       []string
   784  	EmailAddresses []string
   785  	IPAddresses    []net.IP
   786  	URIs           []*url.URL
   787  
   788  	// Name constraints
   789  	PermittedDNSDomainsCritical bool // if true then the name constraints are marked critical.
   790  	PermittedDNSDomains         []string
   791  	ExcludedDNSDomains          []string
   792  	PermittedIPRanges           []*net.IPNet
   793  	ExcludedIPRanges            []*net.IPNet
   794  	PermittedEmailAddresses     []string
   795  	ExcludedEmailAddresses      []string
   796  	PermittedURIDomains         []string
   797  	ExcludedURIDomains          []string
   798  
   799  	// CRL Distribution Points
   800  	CRLDistributionPoints []string
   801  
   802  	// PolicyIdentifiers contains asn1.ObjectIdentifiers, the components
   803  	// of which are limited to int32. If a certificate contains a policy which
   804  	// cannot be represented by asn1.ObjectIdentifier, it will not be included in
   805  	// PolicyIdentifiers, but will be present in Policies, which contains all parsed
   806  	// policy OIDs.
   807  	// See CreateCertificate for context about how this field and the Policies field
   808  	// interact.
   809  	PolicyIdentifiers []asn1.ObjectIdentifier
   810  
   811  	// Policies contains all policy identifiers included in the certificate.
   812  	// See CreateCertificate for context about how this field and the PolicyIdentifiers field
   813  	// interact.
   814  	// In Go 1.22, encoding/gob cannot handle and ignores this field.
   815  	Policies []OID
   816  
   817  	// InhibitAnyPolicy and InhibitAnyPolicyZero indicate the presence and value
   818  	// of the inhibitAnyPolicy extension.
   819  	//
   820  	// The value of InhibitAnyPolicy indicates the number of additional
   821  	// certificates in the path after this certificate that may use the
   822  	// anyPolicy policy OID to indicate a match with any other policy.
   823  	//
   824  	// When parsing a certificate, a positive non-zero InhibitAnyPolicy means
   825  	// that the field was specified, -1 means it was unset, and
   826  	// InhibitAnyPolicyZero being true mean that the field was explicitly set to
   827  	// zero. The case of InhibitAnyPolicy==0 with InhibitAnyPolicyZero==false
   828  	// should be treated equivalent to -1 (unset).
   829  	InhibitAnyPolicy int
   830  	// InhibitAnyPolicyZero indicates that InhibitAnyPolicy==0 should be
   831  	// interpreted as an actual maximum path length of zero. Otherwise, that
   832  	// combination is interpreted as InhibitAnyPolicy not being set.
   833  	InhibitAnyPolicyZero bool
   834  
   835  	// InhibitPolicyMapping and InhibitPolicyMappingZero indicate the presence
   836  	// and value of the inhibitPolicyMapping field of the policyConstraints
   837  	// extension.
   838  	//
   839  	// The value of InhibitPolicyMapping indicates the number of additional
   840  	// certificates in the path after this certificate that may use policy
   841  	// mapping.
   842  	//
   843  	// When parsing a certificate, a positive non-zero InhibitPolicyMapping
   844  	// means that the field was specified, -1 means it was unset, and
   845  	// InhibitPolicyMappingZero being true mean that the field was explicitly
   846  	// set to zero. The case of InhibitPolicyMapping==0 with
   847  	// InhibitPolicyMappingZero==false should be treated equivalent to -1
   848  	// (unset).
   849  	InhibitPolicyMapping int
   850  	// InhibitPolicyMappingZero indicates that InhibitPolicyMapping==0 should be
   851  	// interpreted as an actual maximum path length of zero. Otherwise, that
   852  	// combination is interpreted as InhibitAnyPolicy not being set.
   853  	InhibitPolicyMappingZero bool
   854  
   855  	// RequireExplicitPolicy and RequireExplicitPolicyZero indicate the presence
   856  	// and value of the requireExplicitPolicy field of the policyConstraints
   857  	// extension.
   858  	//
   859  	// The value of RequireExplicitPolicy indicates the number of additional
   860  	// certificates in the path after this certificate before an explicit policy
   861  	// is required for the rest of the path. When an explicit policy is required,
   862  	// each subsequent certificate in the path must contain a required policy OID,
   863  	// or a policy OID which has been declared as equivalent through the policy
   864  	// mapping extension.
   865  	//
   866  	// When parsing a certificate, a positive non-zero RequireExplicitPolicy
   867  	// means that the field was specified, -1 means it was unset, and
   868  	// RequireExplicitPolicyZero being true mean that the field was explicitly
   869  	// set to zero. The case of RequireExplicitPolicy==0 with
   870  	// RequireExplicitPolicyZero==false should be treated equivalent to -1
   871  	// (unset).
   872  	RequireExplicitPolicy int
   873  	// RequireExplicitPolicyZero indicates that RequireExplicitPolicy==0 should be
   874  	// interpreted as an actual maximum path length of zero. Otherwise, that
   875  	// combination is interpreted as InhibitAnyPolicy not being set.
   876  	RequireExplicitPolicyZero bool
   877  
   878  	// PolicyMappings contains a list of policy mappings included in the certificate.
   879  	PolicyMappings []PolicyMapping
   880  }
   881  
   882  // PolicyMapping represents a policy mapping entry in the policyMappings extension.
   883  type PolicyMapping struct {
   884  	// IssuerDomainPolicy contains a policy OID the issuing certificate considers
   885  	// equivalent to SubjectDomainPolicy in the subject certificate.
   886  	IssuerDomainPolicy OID
   887  	// SubjectDomainPolicy contains a OID the issuing certificate considers
   888  	// equivalent to IssuerDomainPolicy in the subject certificate.
   889  	SubjectDomainPolicy OID
   890  }
   891  
   892  // ErrUnsupportedAlgorithm results from attempting to perform an operation that
   893  // involves algorithms that are not currently implemented.
   894  var ErrUnsupportedAlgorithm = errors.New("x509: cannot verify signature: algorithm unimplemented")
   895  
   896  // An InsecureAlgorithmError indicates that the [SignatureAlgorithm] used to
   897  // generate the signature is not secure, and the signature has been rejected.
   898  type InsecureAlgorithmError SignatureAlgorithm
   899  
   900  func (e InsecureAlgorithmError) Error() string {
   901  	return fmt.Sprintf("x509: cannot verify signature: insecure algorithm %v", SignatureAlgorithm(e))
   902  }
   903  
   904  // ConstraintViolationError results when a requested usage is not permitted by
   905  // a certificate. For example: checking a signature when the public key isn't a
   906  // certificate signing key.
   907  type ConstraintViolationError struct{}
   908  
   909  func (ConstraintViolationError) Error() string {
   910  	return "x509: invalid signature: parent certificate cannot sign this kind of certificate"
   911  }
   912  
   913  func (c *Certificate) Equal(other *Certificate) bool {
   914  	if c == nil || other == nil {
   915  		return c == other
   916  	}
   917  	return bytes.Equal(c.Raw, other.Raw)
   918  }
   919  
   920  func (c *Certificate) hasSANExtension() bool {
   921  	return oidInExtensions(oidExtensionSubjectAltName, c.Extensions)
   922  }
   923  
   924  // CheckSignatureFrom verifies that the signature on c is a valid signature from parent.
   925  //
   926  // This is a low-level API that performs very limited checks, and not a full
   927  // path verifier. Most users should use [Certificate.Verify] instead.
   928  func (c *Certificate) CheckSignatureFrom(parent *Certificate) error {
   929  	// RFC 5280, 4.2.1.9:
   930  	// "If the basic constraints extension is not present in a version 3
   931  	// certificate, or the extension is present but the cA boolean is not
   932  	// asserted, then the certified public key MUST NOT be used to verify
   933  	// certificate signatures."
   934  	if parent.Version == 3 && !parent.BasicConstraintsValid ||
   935  		parent.BasicConstraintsValid && !parent.IsCA {
   936  		return ConstraintViolationError{}
   937  	}
   938  
   939  	if parent.KeyUsage != 0 && parent.KeyUsage&KeyUsageCertSign == 0 {
   940  		return ConstraintViolationError{}
   941  	}
   942  
   943  	if parent.PublicKeyAlgorithm == UnknownPublicKeyAlgorithm {
   944  		return ErrUnsupportedAlgorithm
   945  	}
   946  
   947  	return checkSignature(c.SignatureAlgorithm, c.RawTBSCertificate, c.Signature, parent.PublicKey, false)
   948  }
   949  
   950  // CheckSignature verifies that signature is a valid signature over signed from
   951  // c's public key.
   952  //
   953  // This is a low-level API that performs no validity checks on the certificate.
   954  //
   955  // [MD5WithRSA] signatures are rejected, while [SHA1WithRSA] and [ECDSAWithSHA1]
   956  // signatures are currently accepted.
   957  func (c *Certificate) CheckSignature(algo SignatureAlgorithm, signed, signature []byte) error {
   958  	return checkSignature(algo, signed, signature, c.PublicKey, true)
   959  }
   960  
   961  func (c *Certificate) hasNameConstraints() bool {
   962  	return oidInExtensions(oidExtensionNameConstraints, c.Extensions)
   963  }
   964  
   965  func (c *Certificate) getSANExtension() []byte {
   966  	for _, e := range c.Extensions {
   967  		if e.Id.Equal(oidExtensionSubjectAltName) {
   968  			return e.Value
   969  		}
   970  	}
   971  	return nil
   972  }
   973  
   974  func signaturePublicKeyAlgoMismatchError(expectedPubKeyAlgo PublicKeyAlgorithm, pubKey any) error {
   975  	return fmt.Errorf("x509: signature algorithm specifies an %s public key, but have public key of type %T", expectedPubKeyAlgo.String(), pubKey)
   976  }
   977  
   978  // checkSignature verifies that signature is a valid signature over signed from
   979  // a crypto.PublicKey.
   980  func checkSignature(algo SignatureAlgorithm, signed, signature []byte, publicKey crypto.PublicKey, allowSHA1 bool) (err error) {
   981  	var hashType crypto.Hash
   982  	var pubKeyAlgo PublicKeyAlgorithm
   983  
   984  	for _, details := range signatureAlgorithmDetails {
   985  		if details.algo == algo {
   986  			hashType = details.hash
   987  			pubKeyAlgo = details.pubKeyAlgo
   988  			break
   989  		}
   990  	}
   991  
   992  	switch hashType {
   993  	case crypto.Hash(0):
   994  		if pubKeyAlgo != Ed25519 {
   995  			return ErrUnsupportedAlgorithm
   996  		}
   997  	case crypto.MD5:
   998  		return InsecureAlgorithmError(algo)
   999  	case crypto.SHA1:
  1000  		// SHA-1 signatures are only allowed for CRLs and CSRs.
  1001  		if !allowSHA1 {
  1002  			return InsecureAlgorithmError(algo)
  1003  		}
  1004  		fallthrough
  1005  	default:
  1006  		if !hashType.Available() {
  1007  			return ErrUnsupportedAlgorithm
  1008  		}
  1009  		h := hashType.New()
  1010  		h.Write(signed)
  1011  		signed = h.Sum(nil)
  1012  	}
  1013  
  1014  	switch pub := publicKey.(type) {
  1015  	case *rsa.PublicKey:
  1016  		if pubKeyAlgo != RSA {
  1017  			return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
  1018  		}
  1019  		if algo.isRSAPSS() {
  1020  			return rsa.VerifyPSS(pub, hashType, signed, signature, &rsa.PSSOptions{SaltLength: rsa.PSSSaltLengthEqualsHash})
  1021  		} else {
  1022  			return rsa.VerifyPKCS1v15(pub, hashType, signed, signature)
  1023  		}
  1024  	case *ecdsa.PublicKey:
  1025  		if pubKeyAlgo != ECDSA {
  1026  			return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
  1027  		}
  1028  		if !ecdsa.VerifyASN1(pub, signed, signature) {
  1029  			return errors.New("x509: ECDSA verification failure")
  1030  		}
  1031  		return
  1032  	case ed25519.PublicKey:
  1033  		if pubKeyAlgo != Ed25519 {
  1034  			return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
  1035  		}
  1036  		if !ed25519.Verify(pub, signed, signature) {
  1037  			return errors.New("x509: Ed25519 verification failure")
  1038  		}
  1039  		return
  1040  	}
  1041  	return ErrUnsupportedAlgorithm
  1042  }
  1043  
  1044  // CheckCRLSignature checks that the signature in crl is from c.
  1045  //
  1046  // Deprecated: Use [RevocationList.CheckSignatureFrom] instead.
  1047  func (c *Certificate) CheckCRLSignature(crl *pkix.CertificateList) error {
  1048  	algo := getSignatureAlgorithmFromAI(crl.SignatureAlgorithm)
  1049  	return c.CheckSignature(algo, crl.TBSCertList.Raw, crl.SignatureValue.RightAlign())
  1050  }
  1051  
  1052  type UnhandledCriticalExtension struct{}
  1053  
  1054  func (h UnhandledCriticalExtension) Error() string {
  1055  	return "x509: unhandled critical extension"
  1056  }
  1057  
  1058  type basicConstraints struct {
  1059  	IsCA       bool `asn1:"optional"`
  1060  	MaxPathLen int  `asn1:"optional,default:-1"`
  1061  }
  1062  
  1063  // RFC 5280 4.2.1.4
  1064  type policyInformation struct {
  1065  	Policy asn1.ObjectIdentifier
  1066  	// policyQualifiers omitted
  1067  }
  1068  
  1069  const (
  1070  	nameTypeEmail = 1
  1071  	nameTypeDNS   = 2
  1072  	nameTypeURI   = 6
  1073  	nameTypeIP    = 7
  1074  )
  1075  
  1076  // RFC 5280, 4.2.2.1
  1077  type authorityInfoAccess struct {
  1078  	Method   asn1.ObjectIdentifier
  1079  	Location asn1.RawValue
  1080  }
  1081  
  1082  // RFC 5280, 4.2.1.14
  1083  type distributionPoint struct {
  1084  	DistributionPoint distributionPointName `asn1:"optional,tag:0"`
  1085  	Reason            asn1.BitString        `asn1:"optional,tag:1"`
  1086  	CRLIssuer         asn1.RawValue         `asn1:"optional,tag:2"`
  1087  }
  1088  
  1089  type distributionPointName struct {
  1090  	FullName     []asn1.RawValue  `asn1:"optional,tag:0"`
  1091  	RelativeName pkix.RDNSequence `asn1:"optional,tag:1"`
  1092  }
  1093  
  1094  func reverseBitsInAByte(in byte) byte {
  1095  	b1 := in>>4 | in<<4
  1096  	b2 := b1>>2&0x33 | b1<<2&0xcc
  1097  	b3 := b2>>1&0x55 | b2<<1&0xaa
  1098  	return b3
  1099  }
  1100  
  1101  // asn1BitLength returns the bit-length of bitString by considering the
  1102  // most-significant bit in a byte to be the "first" bit. This convention
  1103  // matches ASN.1, but differs from almost everything else.
  1104  func asn1BitLength(bitString []byte) int {
  1105  	bitLen := len(bitString) * 8
  1106  
  1107  	for i := range bitString {
  1108  		b := bitString[len(bitString)-i-1]
  1109  
  1110  		for bit := uint(0); bit < 8; bit++ {
  1111  			if (b>>bit)&1 == 1 {
  1112  				return bitLen
  1113  			}
  1114  			bitLen--
  1115  		}
  1116  	}
  1117  
  1118  	return 0
  1119  }
  1120  
  1121  var (
  1122  	oidExtensionSubjectKeyId          = []int{2, 5, 29, 14}
  1123  	oidExtensionKeyUsage              = []int{2, 5, 29, 15}
  1124  	oidExtensionExtendedKeyUsage      = []int{2, 5, 29, 37}
  1125  	oidExtensionAuthorityKeyId        = []int{2, 5, 29, 35}
  1126  	oidExtensionBasicConstraints      = []int{2, 5, 29, 19}
  1127  	oidExtensionSubjectAltName        = []int{2, 5, 29, 17}
  1128  	oidExtensionCertificatePolicies   = []int{2, 5, 29, 32}
  1129  	oidExtensionNameConstraints       = []int{2, 5, 29, 30}
  1130  	oidExtensionCRLDistributionPoints = []int{2, 5, 29, 31}
  1131  	oidExtensionAuthorityInfoAccess   = []int{1, 3, 6, 1, 5, 5, 7, 1, 1}
  1132  	oidExtensionCRLNumber             = []int{2, 5, 29, 20}
  1133  	oidExtensionReasonCode            = []int{2, 5, 29, 21}
  1134  )
  1135  
  1136  var (
  1137  	oidAuthorityInfoAccessOcsp    = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 48, 1}
  1138  	oidAuthorityInfoAccessIssuers = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 48, 2}
  1139  )
  1140  
  1141  // oidInExtensions reports whether an extension with the given oid exists in
  1142  // extensions.
  1143  func oidInExtensions(oid asn1.ObjectIdentifier, extensions []pkix.Extension) bool {
  1144  	for _, e := range extensions {
  1145  		if e.Id.Equal(oid) {
  1146  			return true
  1147  		}
  1148  	}
  1149  	return false
  1150  }
  1151  
  1152  // marshalSANs marshals a list of addresses into a the contents of an X.509
  1153  // SubjectAlternativeName extension.
  1154  func marshalSANs(dnsNames, emailAddresses []string, ipAddresses []net.IP, uris []*url.URL) (derBytes []byte, err error) {
  1155  	var rawValues []asn1.RawValue
  1156  	for _, name := range dnsNames {
  1157  		if err := isIA5String(name); err != nil {
  1158  			return nil, err
  1159  		}
  1160  		rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeDNS, Class: 2, Bytes: []byte(name)})
  1161  	}
  1162  	for _, email := range emailAddresses {
  1163  		if err := isIA5String(email); err != nil {
  1164  			return nil, err
  1165  		}
  1166  		rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeEmail, Class: 2, Bytes: []byte(email)})
  1167  	}
  1168  	for _, rawIP := range ipAddresses {
  1169  		// If possible, we always want to encode IPv4 addresses in 4 bytes.
  1170  		ip := rawIP.To4()
  1171  		if ip == nil {
  1172  			ip = rawIP
  1173  		}
  1174  		rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeIP, Class: 2, Bytes: ip})
  1175  	}
  1176  	for _, uri := range uris {
  1177  		uriStr := uri.String()
  1178  		if err := isIA5String(uriStr); err != nil {
  1179  			return nil, err
  1180  		}
  1181  		rawValues = append(rawValues, asn1.RawValue{Tag: nameTypeURI, Class: 2, Bytes: []byte(uriStr)})
  1182  	}
  1183  	return asn1.Marshal(rawValues)
  1184  }
  1185  
  1186  func isIA5String(s string) error {
  1187  	for _, r := range s {
  1188  		// Per RFC5280 "IA5String is limited to the set of ASCII characters"
  1189  		if r > unicode.MaxASCII {
  1190  			return fmt.Errorf("x509: %q cannot be encoded as an IA5String", s)
  1191  		}
  1192  	}
  1193  
  1194  	return nil
  1195  }
  1196  
  1197  var x509usepolicies = godebug.New("x509usepolicies")
  1198  
  1199  func buildCertExtensions(template *Certificate, subjectIsEmpty bool, authorityKeyId []byte, subjectKeyId []byte) (ret []pkix.Extension, err error) {
  1200  	ret = make([]pkix.Extension, 10 /* maximum number of elements. */)
  1201  	n := 0
  1202  
  1203  	if template.KeyUsage != 0 &&
  1204  		!oidInExtensions(oidExtensionKeyUsage, template.ExtraExtensions) {
  1205  		ret[n], err = marshalKeyUsage(template.KeyUsage)
  1206  		if err != nil {
  1207  			return nil, err
  1208  		}
  1209  		n++
  1210  	}
  1211  
  1212  	if (len(template.ExtKeyUsage) > 0 || len(template.UnknownExtKeyUsage) > 0) &&
  1213  		!oidInExtensions(oidExtensionExtendedKeyUsage, template.ExtraExtensions) {
  1214  		ret[n], err = marshalExtKeyUsage(template.ExtKeyUsage, template.UnknownExtKeyUsage)
  1215  		if err != nil {
  1216  			return nil, err
  1217  		}
  1218  		n++
  1219  	}
  1220  
  1221  	if template.BasicConstraintsValid && !oidInExtensions(oidExtensionBasicConstraints, template.ExtraExtensions) {
  1222  		ret[n], err = marshalBasicConstraints(template.IsCA, template.MaxPathLen, template.MaxPathLenZero)
  1223  		if err != nil {
  1224  			return nil, err
  1225  		}
  1226  		n++
  1227  	}
  1228  
  1229  	if len(subjectKeyId) > 0 && !oidInExtensions(oidExtensionSubjectKeyId, template.ExtraExtensions) {
  1230  		ret[n].Id = oidExtensionSubjectKeyId
  1231  		ret[n].Value, err = asn1.Marshal(subjectKeyId)
  1232  		if err != nil {
  1233  			return
  1234  		}
  1235  		n++
  1236  	}
  1237  
  1238  	if len(authorityKeyId) > 0 && !oidInExtensions(oidExtensionAuthorityKeyId, template.ExtraExtensions) {
  1239  		ret[n].Id = oidExtensionAuthorityKeyId
  1240  		ret[n].Value, err = asn1.Marshal(authKeyId{authorityKeyId})
  1241  		if err != nil {
  1242  			return
  1243  		}
  1244  		n++
  1245  	}
  1246  
  1247  	if (len(template.OCSPServer) > 0 || len(template.IssuingCertificateURL) > 0) &&
  1248  		!oidInExtensions(oidExtensionAuthorityInfoAccess, template.ExtraExtensions) {
  1249  		ret[n].Id = oidExtensionAuthorityInfoAccess
  1250  		var aiaValues []authorityInfoAccess
  1251  		for _, name := range template.OCSPServer {
  1252  			aiaValues = append(aiaValues, authorityInfoAccess{
  1253  				Method:   oidAuthorityInfoAccessOcsp,
  1254  				Location: asn1.RawValue{Tag: 6, Class: 2, Bytes: []byte(name)},
  1255  			})
  1256  		}
  1257  		for _, name := range template.IssuingCertificateURL {
  1258  			aiaValues = append(aiaValues, authorityInfoAccess{
  1259  				Method:   oidAuthorityInfoAccessIssuers,
  1260  				Location: asn1.RawValue{Tag: 6, Class: 2, Bytes: []byte(name)},
  1261  			})
  1262  		}
  1263  		ret[n].Value, err = asn1.Marshal(aiaValues)
  1264  		if err != nil {
  1265  			return
  1266  		}
  1267  		n++
  1268  	}
  1269  
  1270  	if (len(template.DNSNames) > 0 || len(template.EmailAddresses) > 0 || len(template.IPAddresses) > 0 || len(template.URIs) > 0) &&
  1271  		!oidInExtensions(oidExtensionSubjectAltName, template.ExtraExtensions) {
  1272  		ret[n].Id = oidExtensionSubjectAltName
  1273  		// From RFC 5280, Section 4.2.1.6:
  1274  		// “If the subject field contains an empty sequence ... then
  1275  		// subjectAltName extension ... is marked as critical”
  1276  		ret[n].Critical = subjectIsEmpty
  1277  		ret[n].Value, err = marshalSANs(template.DNSNames, template.EmailAddresses, template.IPAddresses, template.URIs)
  1278  		if err != nil {
  1279  			return
  1280  		}
  1281  		n++
  1282  	}
  1283  
  1284  	usePolicies := x509usepolicies.Value() != "0"
  1285  	if ((!usePolicies && len(template.PolicyIdentifiers) > 0) || (usePolicies && len(template.Policies) > 0)) &&
  1286  		!oidInExtensions(oidExtensionCertificatePolicies, template.ExtraExtensions) {
  1287  		ret[n], err = marshalCertificatePolicies(template.Policies, template.PolicyIdentifiers)
  1288  		if err != nil {
  1289  			return nil, err
  1290  		}
  1291  		n++
  1292  	}
  1293  
  1294  	if (len(template.PermittedDNSDomains) > 0 || len(template.ExcludedDNSDomains) > 0 ||
  1295  		len(template.PermittedIPRanges) > 0 || len(template.ExcludedIPRanges) > 0 ||
  1296  		len(template.PermittedEmailAddresses) > 0 || len(template.ExcludedEmailAddresses) > 0 ||
  1297  		len(template.PermittedURIDomains) > 0 || len(template.ExcludedURIDomains) > 0) &&
  1298  		!oidInExtensions(oidExtensionNameConstraints, template.ExtraExtensions) {
  1299  		ret[n].Id = oidExtensionNameConstraints
  1300  		ret[n].Critical = template.PermittedDNSDomainsCritical
  1301  
  1302  		ipAndMask := func(ipNet *net.IPNet) []byte {
  1303  			maskedIP := ipNet.IP.Mask(ipNet.Mask)
  1304  			ipAndMask := make([]byte, 0, len(maskedIP)+len(ipNet.Mask))
  1305  			ipAndMask = append(ipAndMask, maskedIP...)
  1306  			ipAndMask = append(ipAndMask, ipNet.Mask...)
  1307  			return ipAndMask
  1308  		}
  1309  
  1310  		serialiseConstraints := func(dns []string, ips []*net.IPNet, emails []string, uriDomains []string) (der []byte, err error) {
  1311  			var b cryptobyte.Builder
  1312  
  1313  			for _, name := range dns {
  1314  				if err = isIA5String(name); err != nil {
  1315  					return nil, err
  1316  				}
  1317  
  1318  				b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1319  					b.AddASN1(cryptobyte_asn1.Tag(2).ContextSpecific(), func(b *cryptobyte.Builder) {
  1320  						b.AddBytes([]byte(name))
  1321  					})
  1322  				})
  1323  			}
  1324  
  1325  			for _, ipNet := range ips {
  1326  				b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1327  					b.AddASN1(cryptobyte_asn1.Tag(7).ContextSpecific(), func(b *cryptobyte.Builder) {
  1328  						b.AddBytes(ipAndMask(ipNet))
  1329  					})
  1330  				})
  1331  			}
  1332  
  1333  			for _, email := range emails {
  1334  				if err = isIA5String(email); err != nil {
  1335  					return nil, err
  1336  				}
  1337  
  1338  				b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1339  					b.AddASN1(cryptobyte_asn1.Tag(1).ContextSpecific(), func(b *cryptobyte.Builder) {
  1340  						b.AddBytes([]byte(email))
  1341  					})
  1342  				})
  1343  			}
  1344  
  1345  			for _, uriDomain := range uriDomains {
  1346  				if err = isIA5String(uriDomain); err != nil {
  1347  					return nil, err
  1348  				}
  1349  
  1350  				b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1351  					b.AddASN1(cryptobyte_asn1.Tag(6).ContextSpecific(), func(b *cryptobyte.Builder) {
  1352  						b.AddBytes([]byte(uriDomain))
  1353  					})
  1354  				})
  1355  			}
  1356  
  1357  			return b.Bytes()
  1358  		}
  1359  
  1360  		permitted, err := serialiseConstraints(template.PermittedDNSDomains, template.PermittedIPRanges, template.PermittedEmailAddresses, template.PermittedURIDomains)
  1361  		if err != nil {
  1362  			return nil, err
  1363  		}
  1364  
  1365  		excluded, err := serialiseConstraints(template.ExcludedDNSDomains, template.ExcludedIPRanges, template.ExcludedEmailAddresses, template.ExcludedURIDomains)
  1366  		if err != nil {
  1367  			return nil, err
  1368  		}
  1369  
  1370  		var b cryptobyte.Builder
  1371  		b.AddASN1(cryptobyte_asn1.SEQUENCE, func(b *cryptobyte.Builder) {
  1372  			if len(permitted) > 0 {
  1373  				b.AddASN1(cryptobyte_asn1.Tag(0).ContextSpecific().Constructed(), func(b *cryptobyte.Builder) {
  1374  					b.AddBytes(permitted)
  1375  				})
  1376  			}
  1377  
  1378  			if len(excluded) > 0 {
  1379  				b.AddASN1(cryptobyte_asn1.Tag(1).ContextSpecific().Constructed(), func(b *cryptobyte.Builder) {
  1380  					b.AddBytes(excluded)
  1381  				})
  1382  			}
  1383  		})
  1384  
  1385  		ret[n].Value, err = b.Bytes()
  1386  		if err != nil {
  1387  			return nil, err
  1388  		}
  1389  		n++
  1390  	}
  1391  
  1392  	if len(template.CRLDistributionPoints) > 0 &&
  1393  		!oidInExtensions(oidExtensionCRLDistributionPoints, template.ExtraExtensions) {
  1394  		ret[n].Id = oidExtensionCRLDistributionPoints
  1395  
  1396  		var crlDp []distributionPoint
  1397  		for _, name := range template.CRLDistributionPoints {
  1398  			dp := distributionPoint{
  1399  				DistributionPoint: distributionPointName{
  1400  					FullName: []asn1.RawValue{
  1401  						{Tag: 6, Class: 2, Bytes: []byte(name)},
  1402  					},
  1403  				},
  1404  			}
  1405  			crlDp = append(crlDp, dp)
  1406  		}
  1407  
  1408  		ret[n].Value, err = asn1.Marshal(crlDp)
  1409  		if err != nil {
  1410  			return
  1411  		}
  1412  		n++
  1413  	}
  1414  
  1415  	// Adding another extension here? Remember to update the maximum number
  1416  	// of elements in the make() at the top of the function and the list of
  1417  	// template fields used in CreateCertificate documentation.
  1418  
  1419  	return append(ret[:n], template.ExtraExtensions...), nil
  1420  }
  1421  
  1422  func marshalKeyUsage(ku KeyUsage) (pkix.Extension, error) {
  1423  	ext := pkix.Extension{Id: oidExtensionKeyUsage, Critical: true}
  1424  
  1425  	var a [2]byte
  1426  	a[0] = reverseBitsInAByte(byte(ku))
  1427  	a[1] = reverseBitsInAByte(byte(ku >> 8))
  1428  
  1429  	l := 1
  1430  	if a[1] != 0 {
  1431  		l = 2
  1432  	}
  1433  
  1434  	bitString := a[:l]
  1435  	var err error
  1436  	ext.Value, err = asn1.Marshal(asn1.BitString{Bytes: bitString, BitLength: asn1BitLength(bitString)})
  1437  	return ext, err
  1438  }
  1439  
  1440  func marshalExtKeyUsage(extUsages []ExtKeyUsage, unknownUsages []asn1.ObjectIdentifier) (pkix.Extension, error) {
  1441  	ext := pkix.Extension{Id: oidExtensionExtendedKeyUsage}
  1442  
  1443  	oids := make([]asn1.ObjectIdentifier, len(extUsages)+len(unknownUsages))
  1444  	for i, u := range extUsages {
  1445  		if oid, ok := oidFromExtKeyUsage(u); ok {
  1446  			oids[i] = oid
  1447  		} else {
  1448  			return ext, errors.New("x509: unknown extended key usage")
  1449  		}
  1450  	}
  1451  
  1452  	copy(oids[len(extUsages):], unknownUsages)
  1453  
  1454  	var err error
  1455  	ext.Value, err = asn1.Marshal(oids)
  1456  	return ext, err
  1457  }
  1458  
  1459  func marshalBasicConstraints(isCA bool, maxPathLen int, maxPathLenZero bool) (pkix.Extension, error) {
  1460  	ext := pkix.Extension{Id: oidExtensionBasicConstraints, Critical: true}
  1461  	// Leaving MaxPathLen as zero indicates that no maximum path
  1462  	// length is desired, unless MaxPathLenZero is set. A value of
  1463  	// -1 causes encoding/asn1 to omit the value as desired.
  1464  	if maxPathLen == 0 && !maxPathLenZero {
  1465  		maxPathLen = -1
  1466  	}
  1467  	var err error
  1468  	ext.Value, err = asn1.Marshal(basicConstraints{isCA, maxPathLen})
  1469  	return ext, err
  1470  }
  1471  
  1472  func marshalCertificatePolicies(policies []OID, policyIdentifiers []asn1.ObjectIdentifier) (pkix.Extension, error) {
  1473  	ext := pkix.Extension{Id: oidExtensionCertificatePolicies}
  1474  
  1475  	b := cryptobyte.NewBuilder(make([]byte, 0, 128))
  1476  	b.AddASN1(cryptobyte_asn1.SEQUENCE, func(child *cryptobyte.Builder) {
  1477  		if x509usepolicies.Value() != "0" {
  1478  			x509usepolicies.IncNonDefault()
  1479  			for _, v := range policies {
  1480  				child.AddASN1(cryptobyte_asn1.SEQUENCE, func(child *cryptobyte.Builder) {
  1481  					child.AddASN1(cryptobyte_asn1.OBJECT_IDENTIFIER, func(child *cryptobyte.Builder) {
  1482  						if len(v.der) == 0 {
  1483  							child.SetError(errors.New("invalid policy object identifier"))
  1484  							return
  1485  						}
  1486  						child.AddBytes(v.der)
  1487  					})
  1488  				})
  1489  			}
  1490  		} else {
  1491  			for _, v := range policyIdentifiers {
  1492  				child.AddASN1(cryptobyte_asn1.SEQUENCE, func(child *cryptobyte.Builder) {
  1493  					child.AddASN1ObjectIdentifier(v)
  1494  				})
  1495  			}
  1496  		}
  1497  	})
  1498  
  1499  	var err error
  1500  	ext.Value, err = b.Bytes()
  1501  	return ext, err
  1502  }
  1503  
  1504  func buildCSRExtensions(template *CertificateRequest) ([]pkix.Extension, error) {
  1505  	var ret []pkix.Extension
  1506  
  1507  	if (len(template.DNSNames) > 0 || len(template.EmailAddresses) > 0 || len(template.IPAddresses) > 0 || len(template.URIs) > 0) &&
  1508  		!oidInExtensions(oidExtensionSubjectAltName, template.ExtraExtensions) {
  1509  		sanBytes, err := marshalSANs(template.DNSNames, template.EmailAddresses, template.IPAddresses, template.URIs)
  1510  		if err != nil {
  1511  			return nil, err
  1512  		}
  1513  
  1514  		ret = append(ret, pkix.Extension{
  1515  			Id:    oidExtensionSubjectAltName,
  1516  			Value: sanBytes,
  1517  		})
  1518  	}
  1519  
  1520  	return append(ret, template.ExtraExtensions...), nil
  1521  }
  1522  
  1523  func subjectBytes(cert *Certificate) ([]byte, error) {
  1524  	if len(cert.RawSubject) > 0 {
  1525  		return cert.RawSubject, nil
  1526  	}
  1527  
  1528  	return asn1.Marshal(cert.Subject.ToRDNSequence())
  1529  }
  1530  
  1531  // signingParamsForKey returns the signature algorithm and its Algorithm
  1532  // Identifier to use for signing, based on the key type. If sigAlgo is not zero
  1533  // then it overrides the default.
  1534  func signingParamsForKey(key crypto.Signer, sigAlgo SignatureAlgorithm) (SignatureAlgorithm, pkix.AlgorithmIdentifier, error) {
  1535  	var ai pkix.AlgorithmIdentifier
  1536  	var pubType PublicKeyAlgorithm
  1537  	var defaultAlgo SignatureAlgorithm
  1538  
  1539  	switch pub := key.Public().(type) {
  1540  	case *rsa.PublicKey:
  1541  		pubType = RSA
  1542  		defaultAlgo = SHA256WithRSA
  1543  
  1544  	case *ecdsa.PublicKey:
  1545  		pubType = ECDSA
  1546  		switch pub.Curve {
  1547  		case elliptic.P224(), elliptic.P256():
  1548  			defaultAlgo = ECDSAWithSHA256
  1549  		case elliptic.P384():
  1550  			defaultAlgo = ECDSAWithSHA384
  1551  		case elliptic.P521():
  1552  			defaultAlgo = ECDSAWithSHA512
  1553  		default:
  1554  			return 0, ai, errors.New("x509: unsupported elliptic curve")
  1555  		}
  1556  
  1557  	case ed25519.PublicKey:
  1558  		pubType = Ed25519
  1559  		defaultAlgo = PureEd25519
  1560  
  1561  	default:
  1562  		return 0, ai, errors.New("x509: only RSA, ECDSA and Ed25519 keys supported")
  1563  	}
  1564  
  1565  	if sigAlgo == 0 {
  1566  		sigAlgo = defaultAlgo
  1567  	}
  1568  
  1569  	for _, details := range signatureAlgorithmDetails {
  1570  		if details.algo == sigAlgo {
  1571  			if details.pubKeyAlgo != pubType {
  1572  				return 0, ai, errors.New("x509: requested SignatureAlgorithm does not match private key type")
  1573  			}
  1574  			if details.hash == crypto.MD5 {
  1575  				return 0, ai, errors.New("x509: signing with MD5 is not supported")
  1576  			}
  1577  
  1578  			return sigAlgo, pkix.AlgorithmIdentifier{
  1579  				Algorithm:  details.oid,
  1580  				Parameters: details.params,
  1581  			}, nil
  1582  		}
  1583  	}
  1584  
  1585  	return 0, ai, errors.New("x509: unknown SignatureAlgorithm")
  1586  }
  1587  
  1588  func signTBS(tbs []byte, key crypto.Signer, sigAlg SignatureAlgorithm, rand io.Reader) ([]byte, error) {
  1589  	hashFunc := sigAlg.hashFunc()
  1590  
  1591  	var signerOpts crypto.SignerOpts = hashFunc
  1592  	if sigAlg.isRSAPSS() {
  1593  		signerOpts = &rsa.PSSOptions{
  1594  			SaltLength: rsa.PSSSaltLengthEqualsHash,
  1595  			Hash:       hashFunc,
  1596  		}
  1597  	}
  1598  
  1599  	signature, err := crypto.SignMessage(key, rand, tbs, signerOpts)
  1600  	if err != nil {
  1601  		return nil, err
  1602  	}
  1603  
  1604  	// Check the signature to ensure the crypto.Signer behaved correctly.
  1605  	if err := checkSignature(sigAlg, tbs, signature, key.Public(), true); err != nil {
  1606  		return nil, fmt.Errorf("x509: signature returned by signer is invalid: %w", err)
  1607  	}
  1608  
  1609  	return signature, nil
  1610  }
  1611  
  1612  // emptyASN1Subject is the ASN.1 DER encoding of an empty Subject, which is
  1613  // just an empty SEQUENCE.
  1614  var emptyASN1Subject = []byte{0x30, 0}
  1615  
  1616  // CreateCertificate creates a new X.509 v3 certificate based on a template.
  1617  // The following members of template are currently used:
  1618  //
  1619  //   - AuthorityKeyId
  1620  //   - BasicConstraintsValid
  1621  //   - CRLDistributionPoints
  1622  //   - DNSNames
  1623  //   - EmailAddresses
  1624  //   - ExcludedDNSDomains
  1625  //   - ExcludedEmailAddresses
  1626  //   - ExcludedIPRanges
  1627  //   - ExcludedURIDomains
  1628  //   - ExtKeyUsage
  1629  //   - ExtraExtensions
  1630  //   - IPAddresses
  1631  //   - IsCA
  1632  //   - IssuingCertificateURL
  1633  //   - KeyUsage
  1634  //   - MaxPathLen
  1635  //   - MaxPathLenZero
  1636  //   - NotAfter
  1637  //   - NotBefore
  1638  //   - OCSPServer
  1639  //   - PermittedDNSDomains
  1640  //   - PermittedDNSDomainsCritical
  1641  //   - PermittedEmailAddresses
  1642  //   - PermittedIPRanges
  1643  //   - PermittedURIDomains
  1644  //   - PolicyIdentifiers (see note below)
  1645  //   - Policies (see note below)
  1646  //   - SerialNumber
  1647  //   - SignatureAlgorithm
  1648  //   - Subject
  1649  //   - SubjectKeyId
  1650  //   - URIs
  1651  //   - UnknownExtKeyUsage
  1652  //
  1653  // The certificate is signed by parent. If parent is equal to template then the
  1654  // certificate is self-signed. The parameter pub is the public key of the
  1655  // certificate to be generated and priv is the private key of the signer.
  1656  //
  1657  // The returned slice is the certificate in DER encoding.
  1658  //
  1659  // The currently supported key types are *rsa.PublicKey, *ecdsa.PublicKey and
  1660  // ed25519.PublicKey. pub must be a supported key type, and priv must be a
  1661  // crypto.Signer or crypto.MessageSigner with a supported public key.
  1662  //
  1663  // The AuthorityKeyId will be taken from the SubjectKeyId of parent, if any,
  1664  // unless the resulting certificate is self-signed. Otherwise the value from
  1665  // template will be used.
  1666  //
  1667  // If SubjectKeyId from template is empty and the template is a CA, SubjectKeyId
  1668  // will be generated from the hash of the public key.
  1669  //
  1670  // If template.SerialNumber is nil, a serial number will be generated which
  1671  // conforms to RFC 5280, Section 4.1.2.2 using entropy from rand.
  1672  //
  1673  // The PolicyIdentifier and Policies fields can both be used to marshal certificate
  1674  // policy OIDs. By default, only the Policies is marshaled, but if the
  1675  // GODEBUG setting "x509usepolicies" has the value "0", the PolicyIdentifiers field will
  1676  // be marshaled instead of the Policies field. This changed in Go 1.24. The Policies field can
  1677  // be used to marshal policy OIDs which have components that are larger than 31
  1678  // bits.
  1679  func CreateCertificate(rand io.Reader, template, parent *Certificate, pub, priv any) ([]byte, error) {
  1680  	key, ok := priv.(crypto.Signer)
  1681  	if !ok {
  1682  		return nil, errors.New("x509: certificate private key does not implement crypto.Signer")
  1683  	}
  1684  
  1685  	serialNumber := template.SerialNumber
  1686  	if serialNumber == nil {
  1687  		// Generate a serial number following RFC 5280, Section 4.1.2.2 if one
  1688  		// is not provided. The serial number must be positive and at most 20
  1689  		// octets *when encoded*.
  1690  		serialBytes := make([]byte, 20)
  1691  		if _, err := io.ReadFull(rand, serialBytes); err != nil {
  1692  			return nil, err
  1693  		}
  1694  		// If the top bit is set, the serial will be padded with a leading zero
  1695  		// byte during encoding, so that it's not interpreted as a negative
  1696  		// integer. This padding would make the serial 21 octets so we clear the
  1697  		// top bit to ensure the correct length in all cases.
  1698  		serialBytes[0] &= 0b0111_1111
  1699  		serialNumber = new(big.Int).SetBytes(serialBytes)
  1700  	}
  1701  
  1702  	// RFC 5280 Section 4.1.2.2: serial number must be positive
  1703  	//
  1704  	// We _should_ also restrict serials to <= 20 octets, but it turns out a lot of people
  1705  	// get this wrong, in part because the encoding can itself alter the length of the
  1706  	// serial. For now we accept these non-conformant serials.
  1707  	if serialNumber.Sign() == -1 {
  1708  		return nil, errors.New("x509: serial number must be positive")
  1709  	}
  1710  
  1711  	if template.BasicConstraintsValid && template.MaxPathLen < -1 {
  1712  		return nil, errors.New("x509: invalid MaxPathLen, must be greater or equal to -1")
  1713  	}
  1714  
  1715  	if template.BasicConstraintsValid && !template.IsCA && template.MaxPathLen != -1 && (template.MaxPathLen != 0 || template.MaxPathLenZero) {
  1716  		return nil, errors.New("x509: only CAs are allowed to specify MaxPathLen")
  1717  	}
  1718  
  1719  	signatureAlgorithm, algorithmIdentifier, err := signingParamsForKey(key, template.SignatureAlgorithm)
  1720  	if err != nil {
  1721  		return nil, err
  1722  	}
  1723  
  1724  	publicKeyBytes, publicKeyAlgorithm, err := marshalPublicKey(pub)
  1725  	if err != nil {
  1726  		return nil, err
  1727  	}
  1728  	if getPublicKeyAlgorithmFromOID(publicKeyAlgorithm.Algorithm) == UnknownPublicKeyAlgorithm {
  1729  		return nil, fmt.Errorf("x509: unsupported public key type: %T", pub)
  1730  	}
  1731  
  1732  	asn1Issuer, err := subjectBytes(parent)
  1733  	if err != nil {
  1734  		return nil, err
  1735  	}
  1736  
  1737  	asn1Subject, err := subjectBytes(template)
  1738  	if err != nil {
  1739  		return nil, err
  1740  	}
  1741  
  1742  	authorityKeyId := template.AuthorityKeyId
  1743  	if !bytes.Equal(asn1Issuer, asn1Subject) && len(parent.SubjectKeyId) > 0 {
  1744  		authorityKeyId = parent.SubjectKeyId
  1745  	}
  1746  
  1747  	subjectKeyId := template.SubjectKeyId
  1748  	if len(subjectKeyId) == 0 && template.IsCA {
  1749  		if x509sha256skid.Value() == "0" {
  1750  			x509sha256skid.IncNonDefault()
  1751  			// SubjectKeyId generated using method 1 in RFC 5280, Section 4.2.1.2:
  1752  			//   (1) The keyIdentifier is composed of the 160-bit SHA-1 hash of the
  1753  			//   value of the BIT STRING subjectPublicKey (excluding the tag,
  1754  			//   length, and number of unused bits).
  1755  			h := sha1.Sum(publicKeyBytes)
  1756  			subjectKeyId = h[:]
  1757  		} else {
  1758  			// SubjectKeyId generated using method 1 in RFC 7093, Section 2:
  1759  			//    1) The keyIdentifier is composed of the leftmost 160-bits of the
  1760  			//    SHA-256 hash of the value of the BIT STRING subjectPublicKey
  1761  			//    (excluding the tag, length, and number of unused bits).
  1762  			h := sha256.Sum256(publicKeyBytes)
  1763  			subjectKeyId = h[:20]
  1764  		}
  1765  	}
  1766  
  1767  	// Check that the signer's public key matches the private key, if available.
  1768  	type privateKey interface {
  1769  		Equal(crypto.PublicKey) bool
  1770  	}
  1771  	if privPub, ok := key.Public().(privateKey); !ok {
  1772  		return nil, errors.New("x509: internal error: supported public key does not implement Equal")
  1773  	} else if parent.PublicKey != nil && !privPub.Equal(parent.PublicKey) {
  1774  		return nil, errors.New("x509: provided PrivateKey doesn't match parent's PublicKey")
  1775  	}
  1776  
  1777  	extensions, err := buildCertExtensions(template, bytes.Equal(asn1Subject, emptyASN1Subject), authorityKeyId, subjectKeyId)
  1778  	if err != nil {
  1779  		return nil, err
  1780  	}
  1781  
  1782  	encodedPublicKey := asn1.BitString{BitLength: len(publicKeyBytes) * 8, Bytes: publicKeyBytes}
  1783  	c := tbsCertificate{
  1784  		Version:            2,
  1785  		SerialNumber:       serialNumber,
  1786  		SignatureAlgorithm: algorithmIdentifier,
  1787  		Issuer:             asn1.RawValue{FullBytes: asn1Issuer},
  1788  		Validity:           validity{template.NotBefore.UTC(), template.NotAfter.UTC()},
  1789  		Subject:            asn1.RawValue{FullBytes: asn1Subject},
  1790  		PublicKey:          publicKeyInfo{nil, publicKeyAlgorithm, encodedPublicKey},
  1791  		Extensions:         extensions,
  1792  	}
  1793  
  1794  	tbsCertContents, err := asn1.Marshal(c)
  1795  	if err != nil {
  1796  		return nil, err
  1797  	}
  1798  	c.Raw = tbsCertContents
  1799  
  1800  	signature, err := signTBS(tbsCertContents, key, signatureAlgorithm, rand)
  1801  	if err != nil {
  1802  		return nil, err
  1803  	}
  1804  
  1805  	return asn1.Marshal(certificate{
  1806  		TBSCertificate:     c,
  1807  		SignatureAlgorithm: algorithmIdentifier,
  1808  		SignatureValue:     asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
  1809  	})
  1810  }
  1811  
  1812  var x509sha256skid = godebug.New("x509sha256skid")
  1813  
  1814  // pemCRLPrefix is the magic string that indicates that we have a PEM encoded
  1815  // CRL.
  1816  var pemCRLPrefix = []byte("-----BEGIN X509 CRL")
  1817  
  1818  // pemType is the type of a PEM encoded CRL.
  1819  var pemType = "X509 CRL"
  1820  
  1821  // ParseCRL parses a CRL from the given bytes. It's often the case that PEM
  1822  // encoded CRLs will appear where they should be DER encoded, so this function
  1823  // will transparently handle PEM encoding as long as there isn't any leading
  1824  // garbage.
  1825  //
  1826  // Deprecated: Use [ParseRevocationList] instead.
  1827  func ParseCRL(crlBytes []byte) (*pkix.CertificateList, error) {
  1828  	if bytes.HasPrefix(crlBytes, pemCRLPrefix) {
  1829  		block, _ := pem.Decode(crlBytes)
  1830  		if block != nil && block.Type == pemType {
  1831  			crlBytes = block.Bytes
  1832  		}
  1833  	}
  1834  	return ParseDERCRL(crlBytes)
  1835  }
  1836  
  1837  // ParseDERCRL parses a DER encoded CRL from the given bytes.
  1838  //
  1839  // Deprecated: Use [ParseRevocationList] instead.
  1840  func ParseDERCRL(derBytes []byte) (*pkix.CertificateList, error) {
  1841  	certList := new(pkix.CertificateList)
  1842  	if rest, err := asn1.Unmarshal(derBytes, certList); err != nil {
  1843  		return nil, err
  1844  	} else if len(rest) != 0 {
  1845  		return nil, errors.New("x509: trailing data after CRL")
  1846  	}
  1847  	return certList, nil
  1848  }
  1849  
  1850  // CreateCRL returns a DER encoded CRL, signed by this Certificate, that
  1851  // contains the given list of revoked certificates.
  1852  //
  1853  // Deprecated: this method does not generate an RFC 5280 conformant X.509 v2 CRL.
  1854  // To generate a standards compliant CRL, use [CreateRevocationList] instead.
  1855  func (c *Certificate) CreateCRL(rand io.Reader, priv any, revokedCerts []pkix.RevokedCertificate, now, expiry time.Time) (crlBytes []byte, err error) {
  1856  	key, ok := priv.(crypto.Signer)
  1857  	if !ok {
  1858  		return nil, errors.New("x509: certificate private key does not implement crypto.Signer")
  1859  	}
  1860  
  1861  	signatureAlgorithm, algorithmIdentifier, err := signingParamsForKey(key, 0)
  1862  	if err != nil {
  1863  		return nil, err
  1864  	}
  1865  
  1866  	// Force revocation times to UTC per RFC 5280.
  1867  	revokedCertsUTC := make([]pkix.RevokedCertificate, len(revokedCerts))
  1868  	for i, rc := range revokedCerts {
  1869  		rc.RevocationTime = rc.RevocationTime.UTC()
  1870  		revokedCertsUTC[i] = rc
  1871  	}
  1872  
  1873  	tbsCertList := pkix.TBSCertificateList{
  1874  		Version:             1,
  1875  		Signature:           algorithmIdentifier,
  1876  		Issuer:              c.Subject.ToRDNSequence(),
  1877  		ThisUpdate:          now.UTC(),
  1878  		NextUpdate:          expiry.UTC(),
  1879  		RevokedCertificates: revokedCertsUTC,
  1880  	}
  1881  
  1882  	// Authority Key Id
  1883  	if len(c.SubjectKeyId) > 0 {
  1884  		var aki pkix.Extension
  1885  		aki.Id = oidExtensionAuthorityKeyId
  1886  		aki.Value, err = asn1.Marshal(authKeyId{Id: c.SubjectKeyId})
  1887  		if err != nil {
  1888  			return nil, err
  1889  		}
  1890  		tbsCertList.Extensions = append(tbsCertList.Extensions, aki)
  1891  	}
  1892  
  1893  	tbsCertListContents, err := asn1.Marshal(tbsCertList)
  1894  	if err != nil {
  1895  		return nil, err
  1896  	}
  1897  	tbsCertList.Raw = tbsCertListContents
  1898  
  1899  	signature, err := signTBS(tbsCertListContents, key, signatureAlgorithm, rand)
  1900  	if err != nil {
  1901  		return nil, err
  1902  	}
  1903  
  1904  	return asn1.Marshal(pkix.CertificateList{
  1905  		TBSCertList:        tbsCertList,
  1906  		SignatureAlgorithm: algorithmIdentifier,
  1907  		SignatureValue:     asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
  1908  	})
  1909  }
  1910  
  1911  // CertificateRequest represents a PKCS #10, certificate signature request.
  1912  type CertificateRequest struct {
  1913  	Raw                      []byte // Complete ASN.1 DER content (CSR, signature algorithm and signature).
  1914  	RawTBSCertificateRequest []byte // Certificate request info part of raw ASN.1 DER content.
  1915  	RawSubjectPublicKeyInfo  []byte // DER encoded SubjectPublicKeyInfo.
  1916  	RawSubject               []byte // DER encoded Subject.
  1917  
  1918  	Version            int
  1919  	Signature          []byte
  1920  	SignatureAlgorithm SignatureAlgorithm
  1921  
  1922  	PublicKeyAlgorithm PublicKeyAlgorithm
  1923  	PublicKey          any
  1924  
  1925  	Subject pkix.Name
  1926  
  1927  	// Attributes contains the CSR attributes that can parse as
  1928  	// pkix.AttributeTypeAndValueSET.
  1929  	//
  1930  	// Deprecated: Use Extensions and ExtraExtensions instead for parsing and
  1931  	// generating the requestedExtensions attribute.
  1932  	Attributes []pkix.AttributeTypeAndValueSET
  1933  
  1934  	// Extensions contains all requested extensions, in raw form. When parsing
  1935  	// CSRs, this can be used to extract extensions that are not parsed by this
  1936  	// package.
  1937  	Extensions []pkix.Extension
  1938  
  1939  	// ExtraExtensions contains extensions to be copied, raw, into any CSR
  1940  	// marshaled by CreateCertificateRequest. Values override any extensions
  1941  	// that would otherwise be produced based on the other fields but are
  1942  	// overridden by any extensions specified in Attributes.
  1943  	//
  1944  	// The ExtraExtensions field is not populated by ParseCertificateRequest,
  1945  	// see Extensions instead.
  1946  	ExtraExtensions []pkix.Extension
  1947  
  1948  	// Subject Alternate Name values.
  1949  	DNSNames       []string
  1950  	EmailAddresses []string
  1951  	IPAddresses    []net.IP
  1952  	URIs           []*url.URL
  1953  }
  1954  
  1955  // These structures reflect the ASN.1 structure of X.509 certificate
  1956  // signature requests (see RFC 2986):
  1957  
  1958  type tbsCertificateRequest struct {
  1959  	Raw           asn1.RawContent
  1960  	Version       int
  1961  	Subject       asn1.RawValue
  1962  	PublicKey     publicKeyInfo
  1963  	RawAttributes []asn1.RawValue `asn1:"tag:0"`
  1964  }
  1965  
  1966  type certificateRequest struct {
  1967  	Raw                asn1.RawContent
  1968  	TBSCSR             tbsCertificateRequest
  1969  	SignatureAlgorithm pkix.AlgorithmIdentifier
  1970  	SignatureValue     asn1.BitString
  1971  }
  1972  
  1973  // oidExtensionRequest is a PKCS #9 OBJECT IDENTIFIER that indicates requested
  1974  // extensions in a CSR.
  1975  var oidExtensionRequest = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 9, 14}
  1976  
  1977  // newRawAttributes converts AttributeTypeAndValueSETs from a template
  1978  // CertificateRequest's Attributes into tbsCertificateRequest RawAttributes.
  1979  func newRawAttributes(attributes []pkix.AttributeTypeAndValueSET) ([]asn1.RawValue, error) {
  1980  	var rawAttributes []asn1.RawValue
  1981  	b, err := asn1.Marshal(attributes)
  1982  	if err != nil {
  1983  		return nil, err
  1984  	}
  1985  	rest, err := asn1.Unmarshal(b, &rawAttributes)
  1986  	if err != nil {
  1987  		return nil, err
  1988  	}
  1989  	if len(rest) != 0 {
  1990  		return nil, errors.New("x509: failed to unmarshal raw CSR Attributes")
  1991  	}
  1992  	return rawAttributes, nil
  1993  }
  1994  
  1995  // parseRawAttributes Unmarshals RawAttributes into AttributeTypeAndValueSETs.
  1996  func parseRawAttributes(rawAttributes []asn1.RawValue) []pkix.AttributeTypeAndValueSET {
  1997  	var attributes []pkix.AttributeTypeAndValueSET
  1998  	for _, rawAttr := range rawAttributes {
  1999  		var attr pkix.AttributeTypeAndValueSET
  2000  		rest, err := asn1.Unmarshal(rawAttr.FullBytes, &attr)
  2001  		// Ignore attributes that don't parse into pkix.AttributeTypeAndValueSET
  2002  		// (i.e.: challengePassword or unstructuredName).
  2003  		if err == nil && len(rest) == 0 {
  2004  			attributes = append(attributes, attr)
  2005  		}
  2006  	}
  2007  	return attributes
  2008  }
  2009  
  2010  // parseCSRExtensions parses the attributes from a CSR and extracts any
  2011  // requested extensions.
  2012  func parseCSRExtensions(rawAttributes []asn1.RawValue) ([]pkix.Extension, error) {
  2013  	// pkcs10Attribute reflects the Attribute structure from RFC 2986, Section 4.1.
  2014  	type pkcs10Attribute struct {
  2015  		Id     asn1.ObjectIdentifier
  2016  		Values []asn1.RawValue `asn1:"set"`
  2017  	}
  2018  
  2019  	var ret []pkix.Extension
  2020  	requestedExts := make(map[string]bool)
  2021  	for _, rawAttr := range rawAttributes {
  2022  		var attr pkcs10Attribute
  2023  		if rest, err := asn1.Unmarshal(rawAttr.FullBytes, &attr); err != nil || len(rest) != 0 || len(attr.Values) == 0 {
  2024  			// Ignore attributes that don't parse.
  2025  			continue
  2026  		}
  2027  
  2028  		if !attr.Id.Equal(oidExtensionRequest) {
  2029  			continue
  2030  		}
  2031  
  2032  		var extensions []pkix.Extension
  2033  		if _, err := asn1.Unmarshal(attr.Values[0].FullBytes, &extensions); err != nil {
  2034  			return nil, err
  2035  		}
  2036  		for _, ext := range extensions {
  2037  			oidStr := ext.Id.String()
  2038  			if requestedExts[oidStr] {
  2039  				return nil, errors.New("x509: certificate request contains duplicate requested extensions")
  2040  			}
  2041  			requestedExts[oidStr] = true
  2042  		}
  2043  		ret = append(ret, extensions...)
  2044  	}
  2045  
  2046  	return ret, nil
  2047  }
  2048  
  2049  // CreateCertificateRequest creates a new certificate request based on a
  2050  // template. The following members of template are used:
  2051  //
  2052  //   - SignatureAlgorithm
  2053  //   - Subject
  2054  //   - DNSNames
  2055  //   - EmailAddresses
  2056  //   - IPAddresses
  2057  //   - URIs
  2058  //   - ExtraExtensions
  2059  //   - Attributes (deprecated)
  2060  //
  2061  // priv is the private key to sign the CSR with, and the corresponding public
  2062  // key will be included in the CSR. It must implement crypto.Signer or
  2063  // crypto.MessageSigner and its Public() method must return a *rsa.PublicKey or
  2064  // a *ecdsa.PublicKey or a ed25519.PublicKey. (A *rsa.PrivateKey,
  2065  // *ecdsa.PrivateKey or ed25519.PrivateKey satisfies this.)
  2066  //
  2067  // The returned slice is the certificate request in DER encoding.
  2068  func CreateCertificateRequest(rand io.Reader, template *CertificateRequest, priv any) (csr []byte, err error) {
  2069  	key, ok := priv.(crypto.Signer)
  2070  	if !ok {
  2071  		return nil, errors.New("x509: certificate private key does not implement crypto.Signer")
  2072  	}
  2073  
  2074  	signatureAlgorithm, algorithmIdentifier, err := signingParamsForKey(key, template.SignatureAlgorithm)
  2075  	if err != nil {
  2076  		return nil, err
  2077  	}
  2078  
  2079  	var publicKeyBytes []byte
  2080  	var publicKeyAlgorithm pkix.AlgorithmIdentifier
  2081  	publicKeyBytes, publicKeyAlgorithm, err = marshalPublicKey(key.Public())
  2082  	if err != nil {
  2083  		return nil, err
  2084  	}
  2085  
  2086  	extensions, err := buildCSRExtensions(template)
  2087  	if err != nil {
  2088  		return nil, err
  2089  	}
  2090  
  2091  	// Make a copy of template.Attributes because we may alter it below.
  2092  	attributes := make([]pkix.AttributeTypeAndValueSET, 0, len(template.Attributes))
  2093  	for _, attr := range template.Attributes {
  2094  		values := make([][]pkix.AttributeTypeAndValue, len(attr.Value))
  2095  		copy(values, attr.Value)
  2096  		attributes = append(attributes, pkix.AttributeTypeAndValueSET{
  2097  			Type:  attr.Type,
  2098  			Value: values,
  2099  		})
  2100  	}
  2101  
  2102  	extensionsAppended := false
  2103  	if len(extensions) > 0 {
  2104  		// Append the extensions to an existing attribute if possible.
  2105  		for _, atvSet := range attributes {
  2106  			if !atvSet.Type.Equal(oidExtensionRequest) || len(atvSet.Value) == 0 {
  2107  				continue
  2108  			}
  2109  
  2110  			// specifiedExtensions contains all the extensions that we
  2111  			// found specified via template.Attributes.
  2112  			specifiedExtensions := make(map[string]bool)
  2113  
  2114  			for _, atvs := range atvSet.Value {
  2115  				for _, atv := range atvs {
  2116  					specifiedExtensions[atv.Type.String()] = true
  2117  				}
  2118  			}
  2119  
  2120  			newValue := make([]pkix.AttributeTypeAndValue, 0, len(atvSet.Value[0])+len(extensions))
  2121  			newValue = append(newValue, atvSet.Value[0]...)
  2122  
  2123  			for _, e := range extensions {
  2124  				if specifiedExtensions[e.Id.String()] {
  2125  					// Attributes already contained a value for
  2126  					// this extension and it takes priority.
  2127  					continue
  2128  				}
  2129  
  2130  				newValue = append(newValue, pkix.AttributeTypeAndValue{
  2131  					// There is no place for the critical
  2132  					// flag in an AttributeTypeAndValue.
  2133  					Type:  e.Id,
  2134  					Value: e.Value,
  2135  				})
  2136  			}
  2137  
  2138  			atvSet.Value[0] = newValue
  2139  			extensionsAppended = true
  2140  			break
  2141  		}
  2142  	}
  2143  
  2144  	rawAttributes, err := newRawAttributes(attributes)
  2145  	if err != nil {
  2146  		return nil, err
  2147  	}
  2148  
  2149  	// If not included in attributes, add a new attribute for the
  2150  	// extensions.
  2151  	if len(extensions) > 0 && !extensionsAppended {
  2152  		attr := struct {
  2153  			Type  asn1.ObjectIdentifier
  2154  			Value [][]pkix.Extension `asn1:"set"`
  2155  		}{
  2156  			Type:  oidExtensionRequest,
  2157  			Value: [][]pkix.Extension{extensions},
  2158  		}
  2159  
  2160  		b, err := asn1.Marshal(attr)
  2161  		if err != nil {
  2162  			return nil, errors.New("x509: failed to serialise extensions attribute: " + err.Error())
  2163  		}
  2164  
  2165  		var rawValue asn1.RawValue
  2166  		if _, err := asn1.Unmarshal(b, &rawValue); err != nil {
  2167  			return nil, err
  2168  		}
  2169  
  2170  		rawAttributes = append(rawAttributes, rawValue)
  2171  	}
  2172  
  2173  	asn1Subject := template.RawSubject
  2174  	if len(asn1Subject) == 0 {
  2175  		asn1Subject, err = asn1.Marshal(template.Subject.ToRDNSequence())
  2176  		if err != nil {
  2177  			return nil, err
  2178  		}
  2179  	}
  2180  
  2181  	tbsCSR := tbsCertificateRequest{
  2182  		Version: 0, // PKCS #10, RFC 2986
  2183  		Subject: asn1.RawValue{FullBytes: asn1Subject},
  2184  		PublicKey: publicKeyInfo{
  2185  			Algorithm: publicKeyAlgorithm,
  2186  			PublicKey: asn1.BitString{
  2187  				Bytes:     publicKeyBytes,
  2188  				BitLength: len(publicKeyBytes) * 8,
  2189  			},
  2190  		},
  2191  		RawAttributes: rawAttributes,
  2192  	}
  2193  
  2194  	tbsCSRContents, err := asn1.Marshal(tbsCSR)
  2195  	if err != nil {
  2196  		return nil, err
  2197  	}
  2198  	tbsCSR.Raw = tbsCSRContents
  2199  
  2200  	signature, err := signTBS(tbsCSRContents, key, signatureAlgorithm, rand)
  2201  	if err != nil {
  2202  		return nil, err
  2203  	}
  2204  
  2205  	return asn1.Marshal(certificateRequest{
  2206  		TBSCSR:             tbsCSR,
  2207  		SignatureAlgorithm: algorithmIdentifier,
  2208  		SignatureValue:     asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
  2209  	})
  2210  }
  2211  
  2212  // ParseCertificateRequest parses a single certificate request from the
  2213  // given ASN.1 DER data.
  2214  func ParseCertificateRequest(asn1Data []byte) (*CertificateRequest, error) {
  2215  	var csr certificateRequest
  2216  
  2217  	rest, err := asn1.Unmarshal(asn1Data, &csr)
  2218  	if err != nil {
  2219  		return nil, err
  2220  	} else if len(rest) != 0 {
  2221  		return nil, asn1.SyntaxError{Msg: "trailing data"}
  2222  	}
  2223  
  2224  	return parseCertificateRequest(&csr)
  2225  }
  2226  
  2227  func parseCertificateRequest(in *certificateRequest) (*CertificateRequest, error) {
  2228  	out := &CertificateRequest{
  2229  		Raw:                      in.Raw,
  2230  		RawTBSCertificateRequest: in.TBSCSR.Raw,
  2231  		RawSubjectPublicKeyInfo:  in.TBSCSR.PublicKey.Raw,
  2232  		RawSubject:               in.TBSCSR.Subject.FullBytes,
  2233  
  2234  		Signature:          in.SignatureValue.RightAlign(),
  2235  		SignatureAlgorithm: getSignatureAlgorithmFromAI(in.SignatureAlgorithm),
  2236  
  2237  		PublicKeyAlgorithm: getPublicKeyAlgorithmFromOID(in.TBSCSR.PublicKey.Algorithm.Algorithm),
  2238  
  2239  		Version:    in.TBSCSR.Version,
  2240  		Attributes: parseRawAttributes(in.TBSCSR.RawAttributes),
  2241  	}
  2242  
  2243  	var err error
  2244  	if out.PublicKeyAlgorithm != UnknownPublicKeyAlgorithm {
  2245  		out.PublicKey, err = parsePublicKey(&in.TBSCSR.PublicKey)
  2246  		if err != nil {
  2247  			return nil, err
  2248  		}
  2249  	}
  2250  
  2251  	var subject pkix.RDNSequence
  2252  	if rest, err := asn1.Unmarshal(in.TBSCSR.Subject.FullBytes, &subject); err != nil {
  2253  		return nil, err
  2254  	} else if len(rest) != 0 {
  2255  		return nil, errors.New("x509: trailing data after X.509 Subject")
  2256  	}
  2257  
  2258  	out.Subject.FillFromRDNSequence(&subject)
  2259  
  2260  	if out.Extensions, err = parseCSRExtensions(in.TBSCSR.RawAttributes); err != nil {
  2261  		return nil, err
  2262  	}
  2263  
  2264  	for _, extension := range out.Extensions {
  2265  		switch {
  2266  		case extension.Id.Equal(oidExtensionSubjectAltName):
  2267  			out.DNSNames, out.EmailAddresses, out.IPAddresses, out.URIs, err = parseSANExtension(extension.Value)
  2268  			if err != nil {
  2269  				return nil, err
  2270  			}
  2271  		}
  2272  	}
  2273  
  2274  	return out, nil
  2275  }
  2276  
  2277  // CheckSignature reports whether the signature on c is valid.
  2278  func (c *CertificateRequest) CheckSignature() error {
  2279  	return checkSignature(c.SignatureAlgorithm, c.RawTBSCertificateRequest, c.Signature, c.PublicKey, true)
  2280  }
  2281  
  2282  // RevocationListEntry represents an entry in the revokedCertificates
  2283  // sequence of a CRL.
  2284  type RevocationListEntry struct {
  2285  	// Raw contains the raw bytes of the revokedCertificates entry. It is set when
  2286  	// parsing a CRL; it is ignored when generating a CRL.
  2287  	Raw []byte
  2288  
  2289  	// SerialNumber represents the serial number of a revoked certificate. It is
  2290  	// both used when creating a CRL and populated when parsing a CRL. It must not
  2291  	// be nil.
  2292  	SerialNumber *big.Int
  2293  	// RevocationTime represents the time at which the certificate was revoked. It
  2294  	// is both used when creating a CRL and populated when parsing a CRL. It must
  2295  	// not be the zero time.
  2296  	RevocationTime time.Time
  2297  	// ReasonCode represents the reason for revocation, using the integer enum
  2298  	// values specified in RFC 5280 Section 5.3.1. When creating a CRL, the zero
  2299  	// value will result in the reasonCode extension being omitted. When parsing a
  2300  	// CRL, the zero value may represent either the reasonCode extension being
  2301  	// absent (which implies the default revocation reason of 0/Unspecified), or
  2302  	// it may represent the reasonCode extension being present and explicitly
  2303  	// containing a value of 0/Unspecified (which should not happen according to
  2304  	// the DER encoding rules, but can and does happen anyway).
  2305  	ReasonCode int
  2306  
  2307  	// Extensions contains raw X.509 extensions. When parsing CRL entries,
  2308  	// this can be used to extract non-critical extensions that are not
  2309  	// parsed by this package. When marshaling CRL entries, the Extensions
  2310  	// field is ignored, see ExtraExtensions.
  2311  	Extensions []pkix.Extension
  2312  	// ExtraExtensions contains extensions to be copied, raw, into any
  2313  	// marshaled CRL entries. Values override any extensions that would
  2314  	// otherwise be produced based on the other fields. The ExtraExtensions
  2315  	// field is not populated when parsing CRL entries, see Extensions.
  2316  	ExtraExtensions []pkix.Extension
  2317  }
  2318  
  2319  // RevocationList represents a [Certificate] Revocation List (CRL) as specified
  2320  // by RFC 5280.
  2321  type RevocationList struct {
  2322  	// Raw contains the complete ASN.1 DER content of the CRL (tbsCertList,
  2323  	// signatureAlgorithm, and signatureValue.)
  2324  	Raw []byte
  2325  	// RawTBSRevocationList contains just the tbsCertList portion of the ASN.1
  2326  	// DER.
  2327  	RawTBSRevocationList []byte
  2328  	// RawIssuer contains the DER encoded Issuer.
  2329  	RawIssuer []byte
  2330  
  2331  	// Issuer contains the DN of the issuing certificate.
  2332  	Issuer pkix.Name
  2333  	// AuthorityKeyId is used to identify the public key associated with the
  2334  	// issuing certificate. It is populated from the authorityKeyIdentifier
  2335  	// extension when parsing a CRL. It is ignored when creating a CRL; the
  2336  	// extension is populated from the issuing certificate itself.
  2337  	AuthorityKeyId []byte
  2338  
  2339  	Signature []byte
  2340  	// SignatureAlgorithm is used to determine the signature algorithm to be
  2341  	// used when signing the CRL. If 0 the default algorithm for the signing
  2342  	// key will be used.
  2343  	SignatureAlgorithm SignatureAlgorithm
  2344  
  2345  	// RevokedCertificateEntries represents the revokedCertificates sequence in
  2346  	// the CRL. It is used when creating a CRL and also populated when parsing a
  2347  	// CRL. When creating a CRL, it may be empty or nil, in which case the
  2348  	// revokedCertificates ASN.1 sequence will be omitted from the CRL entirely.
  2349  	RevokedCertificateEntries []RevocationListEntry
  2350  
  2351  	// RevokedCertificates is used to populate the revokedCertificates
  2352  	// sequence in the CRL if RevokedCertificateEntries is empty. It may be empty
  2353  	// or nil, in which case an empty CRL will be created.
  2354  	//
  2355  	// Deprecated: Use RevokedCertificateEntries instead.
  2356  	RevokedCertificates []pkix.RevokedCertificate
  2357  
  2358  	// Number is used to populate the X.509 v2 cRLNumber extension in the CRL,
  2359  	// which should be a monotonically increasing sequence number for a given
  2360  	// CRL scope and CRL issuer. It is also populated from the cRLNumber
  2361  	// extension when parsing a CRL.
  2362  	Number *big.Int
  2363  
  2364  	// ThisUpdate is used to populate the thisUpdate field in the CRL, which
  2365  	// indicates the issuance date of the CRL.
  2366  	ThisUpdate time.Time
  2367  	// NextUpdate is used to populate the nextUpdate field in the CRL, which
  2368  	// indicates the date by which the next CRL will be issued. NextUpdate
  2369  	// must be greater than ThisUpdate.
  2370  	NextUpdate time.Time
  2371  
  2372  	// Extensions contains raw X.509 extensions. When creating a CRL,
  2373  	// the Extensions field is ignored, see ExtraExtensions.
  2374  	Extensions []pkix.Extension
  2375  
  2376  	// ExtraExtensions contains any additional extensions to add directly to
  2377  	// the CRL.
  2378  	ExtraExtensions []pkix.Extension
  2379  }
  2380  
  2381  // These structures reflect the ASN.1 structure of X.509 CRLs better than
  2382  // the existing crypto/x509/pkix variants do. These mirror the existing
  2383  // certificate structs in this file.
  2384  //
  2385  // Notably, we include issuer as an asn1.RawValue, mirroring the behavior of
  2386  // tbsCertificate and allowing raw (unparsed) subjects to be passed cleanly.
  2387  type certificateList struct {
  2388  	TBSCertList        tbsCertificateList
  2389  	SignatureAlgorithm pkix.AlgorithmIdentifier
  2390  	SignatureValue     asn1.BitString
  2391  }
  2392  
  2393  type tbsCertificateList struct {
  2394  	Raw                 asn1.RawContent
  2395  	Version             int `asn1:"optional,default:0"`
  2396  	Signature           pkix.AlgorithmIdentifier
  2397  	Issuer              asn1.RawValue
  2398  	ThisUpdate          time.Time
  2399  	NextUpdate          time.Time                 `asn1:"optional"`
  2400  	RevokedCertificates []pkix.RevokedCertificate `asn1:"optional"`
  2401  	Extensions          []pkix.Extension          `asn1:"tag:0,optional,explicit"`
  2402  }
  2403  
  2404  // CreateRevocationList creates a new X.509 v2 [Certificate] Revocation List,
  2405  // according to RFC 5280, based on template.
  2406  //
  2407  // The CRL is signed by priv which should be a crypto.Signer or
  2408  // crypto.MessageSigner associated with the public key in the issuer
  2409  // certificate.
  2410  //
  2411  // The issuer may not be nil, and the crlSign bit must be set in [KeyUsage] in
  2412  // order to use it as a CRL issuer.
  2413  //
  2414  // The issuer distinguished name CRL field and authority key identifier
  2415  // extension are populated using the issuer certificate. issuer must have
  2416  // SubjectKeyId set.
  2417  func CreateRevocationList(rand io.Reader, template *RevocationList, issuer *Certificate, priv crypto.Signer) ([]byte, error) {
  2418  	if template == nil {
  2419  		return nil, errors.New("x509: template can not be nil")
  2420  	}
  2421  	if issuer == nil {
  2422  		return nil, errors.New("x509: issuer can not be nil")
  2423  	}
  2424  	if (issuer.KeyUsage & KeyUsageCRLSign) == 0 {
  2425  		return nil, errors.New("x509: issuer must have the crlSign key usage bit set")
  2426  	}
  2427  	if len(issuer.SubjectKeyId) == 0 {
  2428  		return nil, errors.New("x509: issuer certificate doesn't contain a subject key identifier")
  2429  	}
  2430  	if template.NextUpdate.Before(template.ThisUpdate) {
  2431  		return nil, errors.New("x509: template.ThisUpdate is after template.NextUpdate")
  2432  	}
  2433  	if template.Number == nil {
  2434  		return nil, errors.New("x509: template contains nil Number field")
  2435  	}
  2436  
  2437  	signatureAlgorithm, algorithmIdentifier, err := signingParamsForKey(priv, template.SignatureAlgorithm)
  2438  	if err != nil {
  2439  		return nil, err
  2440  	}
  2441  
  2442  	var revokedCerts []pkix.RevokedCertificate
  2443  	// Only process the deprecated RevokedCertificates field if it is populated
  2444  	// and the new RevokedCertificateEntries field is not populated.
  2445  	if len(template.RevokedCertificates) > 0 && len(template.RevokedCertificateEntries) == 0 {
  2446  		// Force revocation times to UTC per RFC 5280.
  2447  		revokedCerts = make([]pkix.RevokedCertificate, len(template.RevokedCertificates))
  2448  		for i, rc := range template.RevokedCertificates {
  2449  			rc.RevocationTime = rc.RevocationTime.UTC()
  2450  			revokedCerts[i] = rc
  2451  		}
  2452  	} else {
  2453  		// Convert the ReasonCode field to a proper extension, and force revocation
  2454  		// times to UTC per RFC 5280.
  2455  		revokedCerts = make([]pkix.RevokedCertificate, len(template.RevokedCertificateEntries))
  2456  		for i, rce := range template.RevokedCertificateEntries {
  2457  			if rce.SerialNumber == nil {
  2458  				return nil, errors.New("x509: template contains entry with nil SerialNumber field")
  2459  			}
  2460  			if rce.RevocationTime.IsZero() {
  2461  				return nil, errors.New("x509: template contains entry with zero RevocationTime field")
  2462  			}
  2463  
  2464  			rc := pkix.RevokedCertificate{
  2465  				SerialNumber:   rce.SerialNumber,
  2466  				RevocationTime: rce.RevocationTime.UTC(),
  2467  			}
  2468  
  2469  			// Copy over any extra extensions, except for a Reason Code extension,
  2470  			// because we'll synthesize that ourselves to ensure it is correct.
  2471  			exts := make([]pkix.Extension, 0, len(rce.ExtraExtensions))
  2472  			for _, ext := range rce.ExtraExtensions {
  2473  				if ext.Id.Equal(oidExtensionReasonCode) {
  2474  					return nil, errors.New("x509: template contains entry with ReasonCode ExtraExtension; use ReasonCode field instead")
  2475  				}
  2476  				exts = append(exts, ext)
  2477  			}
  2478  
  2479  			// Only add a reasonCode extension if the reason is non-zero, as per
  2480  			// RFC 5280 Section 5.3.1.
  2481  			if rce.ReasonCode != 0 {
  2482  				reasonBytes, err := asn1.Marshal(asn1.Enumerated(rce.ReasonCode))
  2483  				if err != nil {
  2484  					return nil, err
  2485  				}
  2486  
  2487  				exts = append(exts, pkix.Extension{
  2488  					Id:    oidExtensionReasonCode,
  2489  					Value: reasonBytes,
  2490  				})
  2491  			}
  2492  
  2493  			if len(exts) > 0 {
  2494  				rc.Extensions = exts
  2495  			}
  2496  			revokedCerts[i] = rc
  2497  		}
  2498  	}
  2499  
  2500  	aki, err := asn1.Marshal(authKeyId{Id: issuer.SubjectKeyId})
  2501  	if err != nil {
  2502  		return nil, err
  2503  	}
  2504  
  2505  	if numBytes := template.Number.Bytes(); len(numBytes) > 20 || (len(numBytes) == 20 && numBytes[0]&0x80 != 0) {
  2506  		return nil, errors.New("x509: CRL number exceeds 20 octets")
  2507  	}
  2508  	crlNum, err := asn1.Marshal(template.Number)
  2509  	if err != nil {
  2510  		return nil, err
  2511  	}
  2512  
  2513  	// Correctly use the issuer's subject sequence if one is specified.
  2514  	issuerSubject, err := subjectBytes(issuer)
  2515  	if err != nil {
  2516  		return nil, err
  2517  	}
  2518  
  2519  	tbsCertList := tbsCertificateList{
  2520  		Version:    1, // v2
  2521  		Signature:  algorithmIdentifier,
  2522  		Issuer:     asn1.RawValue{FullBytes: issuerSubject},
  2523  		ThisUpdate: template.ThisUpdate.UTC(),
  2524  		NextUpdate: template.NextUpdate.UTC(),
  2525  		Extensions: []pkix.Extension{
  2526  			{
  2527  				Id:    oidExtensionAuthorityKeyId,
  2528  				Value: aki,
  2529  			},
  2530  			{
  2531  				Id:    oidExtensionCRLNumber,
  2532  				Value: crlNum,
  2533  			},
  2534  		},
  2535  	}
  2536  	if len(revokedCerts) > 0 {
  2537  		tbsCertList.RevokedCertificates = revokedCerts
  2538  	}
  2539  
  2540  	if len(template.ExtraExtensions) > 0 {
  2541  		tbsCertList.Extensions = append(tbsCertList.Extensions, template.ExtraExtensions...)
  2542  	}
  2543  
  2544  	tbsCertListContents, err := asn1.Marshal(tbsCertList)
  2545  	if err != nil {
  2546  		return nil, err
  2547  	}
  2548  
  2549  	// Optimization to only marshal this struct once, when signing and
  2550  	// then embedding in certificateList below.
  2551  	tbsCertList.Raw = tbsCertListContents
  2552  
  2553  	signature, err := signTBS(tbsCertListContents, priv, signatureAlgorithm, rand)
  2554  	if err != nil {
  2555  		return nil, err
  2556  	}
  2557  
  2558  	return asn1.Marshal(certificateList{
  2559  		TBSCertList:        tbsCertList,
  2560  		SignatureAlgorithm: algorithmIdentifier,
  2561  		SignatureValue:     asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
  2562  	})
  2563  }
  2564  
  2565  // CheckSignatureFrom verifies that the signature on rl is a valid signature
  2566  // from issuer.
  2567  func (rl *RevocationList) CheckSignatureFrom(parent *Certificate) error {
  2568  	if parent.Version == 3 && !parent.BasicConstraintsValid ||
  2569  		parent.BasicConstraintsValid && !parent.IsCA {
  2570  		return ConstraintViolationError{}
  2571  	}
  2572  
  2573  	if parent.KeyUsage != 0 && parent.KeyUsage&KeyUsageCRLSign == 0 {
  2574  		return ConstraintViolationError{}
  2575  	}
  2576  
  2577  	if parent.PublicKeyAlgorithm == UnknownPublicKeyAlgorithm {
  2578  		return ErrUnsupportedAlgorithm
  2579  	}
  2580  
  2581  	return parent.CheckSignature(rl.SignatureAlgorithm, rl.RawTBSRevocationList, rl.Signature)
  2582  }
  2583  

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