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x509.go
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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package x509 implements a subset of the X.509 standard.
//
// It allows parsing and generating certificates, certificate signing
// requests, certificate revocation lists, and encoded public and private keys.
// It provides a certificate verifier, complete with a chain builder.
//
// The package targets the X.509 technical profile defined by the IETF (RFC
// 2459/3280/5280), and as further restricted by the CA/Browser Forum Baseline
// Requirements. There is minimal support for features outside of these
// profiles, as the primary goal of the package is to provide compatibility
// with the publicly trusted TLS certificate ecosystem and its policies and
// constraints.
//
// On macOS and Windows, certificate verification is handled by system APIs, but
// the package aims to apply consistent validation rules across operating
// systems.
package x509
import (
"bytes"
"crypto"
"crypto/ecdh"
"crypto/ecdsa"
"crypto/ed25519"
"crypto/elliptic"
"crypto/rsa"
"crypto/sha1"
"crypto/x509/pkix"
"encoding/asn1"
"encoding/pem"
"errors"
"fmt"
"internal/godebug"
"io"
"math/big"
"net"
"net/url"
"strconv"
"time"
"unicode"
// Explicitly import these for their crypto.RegisterHash init side-effects.
// Keep these as blank imports, even if they're imported above.
_ "crypto/sha1"
_ "crypto/sha256"
_ "crypto/sha512"
"golang.org/x/crypto/cryptobyte"
cryptobyte_asn1 "golang.org/x/crypto/cryptobyte/asn1"
)
// pkixPublicKey reflects a PKIX public key structure. See SubjectPublicKeyInfo
// in RFC 3280.
type pkixPublicKey struct {
Algo pkix.AlgorithmIdentifier
BitString asn1.BitString
}
// ParsePKIXPublicKey parses a public key in PKIX, ASN.1 DER form. The encoded
// public key is a SubjectPublicKeyInfo structure (see RFC 5280, Section 4.1).
//
// It returns a *[rsa.PublicKey], *[dsa.PublicKey], *[ecdsa.PublicKey],
// [ed25519.PublicKey] (not a pointer), or *[ecdh.PublicKey] (for X25519).
// More types might be supported in the future.
//
// This kind of key is commonly encoded in PEM blocks of type "PUBLIC KEY".
func ParsePKIXPublicKey(derBytes []byte) (pub any, err error) {
var pki publicKeyInfo
if rest, err := asn1.Unmarshal(derBytes, &pki); err != nil {
if _, err := asn1.Unmarshal(derBytes, &pkcs1PublicKey{}); err == nil {
return nil, errors.New("x509: failed to parse public key (use ParsePKCS1PublicKey instead for this key format)")
}
return nil, err
} else if len(rest) != 0 {
return nil, errors.New("x509: trailing data after ASN.1 of public-key")
}
return parsePublicKey(&pki)
}
func marshalPublicKey(pub any) (publicKeyBytes []byte, publicKeyAlgorithm pkix.AlgorithmIdentifier, err error) {
switch pub := pub.(type) {
case *rsa.PublicKey:
publicKeyBytes, err = asn1.Marshal(pkcs1PublicKey{
N: pub.N,
E: pub.E,
})
if err != nil {
return nil, pkix.AlgorithmIdentifier{}, err
}
publicKeyAlgorithm.Algorithm = oidPublicKeyRSA
// This is a NULL parameters value which is required by
// RFC 3279, Section 2.3.1.
publicKeyAlgorithm.Parameters = asn1.NullRawValue
case *ecdsa.PublicKey:
oid, ok := oidFromNamedCurve(pub.Curve)
if !ok {
return nil, pkix.AlgorithmIdentifier{}, errors.New("x509: unsupported elliptic curve")
}
if !pub.Curve.IsOnCurve(pub.X, pub.Y) {
return nil, pkix.AlgorithmIdentifier{}, errors.New("x509: invalid elliptic curve public key")
}
publicKeyBytes = elliptic.Marshal(pub.Curve, pub.X, pub.Y)
publicKeyAlgorithm.Algorithm = oidPublicKeyECDSA
var paramBytes []byte
paramBytes, err = asn1.Marshal(oid)
if err != nil {
return
}
publicKeyAlgorithm.Parameters.FullBytes = paramBytes
case ed25519.PublicKey:
publicKeyBytes = pub
publicKeyAlgorithm.Algorithm = oidPublicKeyEd25519
case *ecdh.PublicKey:
publicKeyBytes = pub.Bytes()
if pub.Curve() == ecdh.X25519() {
publicKeyAlgorithm.Algorithm = oidPublicKeyX25519
} else {
oid, ok := oidFromECDHCurve(pub.Curve())
if !ok {
return nil, pkix.AlgorithmIdentifier{}, errors.New("x509: unsupported elliptic curve")
}
publicKeyAlgorithm.Algorithm = oidPublicKeyECDSA
var paramBytes []byte
paramBytes, err = asn1.Marshal(oid)
if err != nil {
return
}
publicKeyAlgorithm.Parameters.FullBytes = paramBytes
}
default:
return nil, pkix.AlgorithmIdentifier{}, fmt.Errorf("x509: unsupported public key type: %T", pub)
}
return publicKeyBytes, publicKeyAlgorithm, nil
}
// MarshalPKIXPublicKey converts a public key to PKIX, ASN.1 DER form.
// The encoded public key is a SubjectPublicKeyInfo structure
// (see RFC 5280, Section 4.1).
//
// The following key types are currently supported: *[rsa.PublicKey],
// *[ecdsa.PublicKey], [ed25519.PublicKey] (not a pointer), and *[ecdh.PublicKey].
// Unsupported key types result in an error.
//
// This kind of key is commonly encoded in PEM blocks of type "PUBLIC KEY".
func MarshalPKIXPublicKey(pub any) ([]byte, error) {
var publicKeyBytes []byte
var publicKeyAlgorithm pkix.AlgorithmIdentifier
var err error
if publicKeyBytes, publicKeyAlgorithm, err = marshalPublicKey(pub); err != nil {
return nil, err
}
pkix := pkixPublicKey{
Algo: publicKeyAlgorithm,
BitString: asn1.BitString{
Bytes: publicKeyBytes,
BitLength: 8 * len(publicKeyBytes),
},
}
ret, _ := asn1.Marshal(pkix)
return ret, nil
}
// These structures reflect the ASN.1 structure of X.509 certificates.:
type certificate struct {
TBSCertificate tbsCertificate
SignatureAlgorithm pkix.AlgorithmIdentifier
SignatureValue asn1.BitString
}
type tbsCertificate struct {
Raw asn1.RawContent
Version int `asn1:"optional,explicit,default:0,tag:0"`
SerialNumber *big.Int
SignatureAlgorithm pkix.AlgorithmIdentifier
Issuer asn1.RawValue
Validity validity
Subject asn1.RawValue
PublicKey publicKeyInfo
UniqueId asn1.BitString `asn1:"optional,tag:1"`
SubjectUniqueId asn1.BitString `asn1:"optional,tag:2"`
Extensions []pkix.Extension `asn1:"omitempty,optional,explicit,tag:3"`
}
type dsaAlgorithmParameters struct {
P, Q, G *big.Int
}
type validity struct {
NotBefore, NotAfter time.Time
}
type publicKeyInfo struct {
Raw asn1.RawContent
Algorithm pkix.AlgorithmIdentifier
PublicKey asn1.BitString
}
// RFC 5280, 4.2.1.1
type authKeyId struct {
Id []byte `asn1:"optional,tag:0"`
}
type SignatureAlgorithm int
const (
UnknownSignatureAlgorithm SignatureAlgorithm = iota
MD2WithRSA // Unsupported.
MD5WithRSA // Only supported for signing, not verification.
SHA1WithRSA // Only supported for signing, and verification of CRLs, CSRs, and OCSP responses.
SHA256WithRSA
SHA384WithRSA
SHA512WithRSA
DSAWithSHA1 // Unsupported.
DSAWithSHA256 // Unsupported.
ECDSAWithSHA1 // Only supported for signing, and verification of CRLs, CSRs, and OCSP responses.
ECDSAWithSHA256
ECDSAWithSHA384
ECDSAWithSHA512
SHA256WithRSAPSS
SHA384WithRSAPSS
SHA512WithRSAPSS
PureEd25519
)
func (algo SignatureAlgorithm) isRSAPSS() bool {
switch algo {
case SHA256WithRSAPSS, SHA384WithRSAPSS, SHA512WithRSAPSS:
return true
default:
return false
}
}
func (algo SignatureAlgorithm) String() string {
for _, details := range signatureAlgorithmDetails {
if details.algo == algo {
return details.name
}
}
return strconv.Itoa(int(algo))
}
type PublicKeyAlgorithm int
const (
UnknownPublicKeyAlgorithm PublicKeyAlgorithm = iota
RSA
DSA // Only supported for parsing.
ECDSA
Ed25519
)
var publicKeyAlgoName = [...]string{
RSA: "RSA",
DSA: "DSA",
ECDSA: "ECDSA",
Ed25519: "Ed25519",
}
func (algo PublicKeyAlgorithm) String() string {
if 0 < algo && int(algo) < len(publicKeyAlgoName) {
return publicKeyAlgoName[algo]
}
return strconv.Itoa(int(algo))
}
// OIDs for signature algorithms
//
// pkcs-1 OBJECT IDENTIFIER ::= {
// iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) 1 }
//
// RFC 3279 2.2.1 RSA Signature Algorithms
//
// md2WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 2 }
//
// md5WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 4 }
//
// sha-1WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 5 }
//
// dsaWithSha1 OBJECT IDENTIFIER ::= {
// iso(1) member-body(2) us(840) x9-57(10040) x9cm(4) 3 }
//
// RFC 3279 2.2.3 ECDSA Signature Algorithm
//
// ecdsa-with-SHA1 OBJECT IDENTIFIER ::= {
// iso(1) member-body(2) us(840) ansi-x962(10045)
// signatures(4) ecdsa-with-SHA1(1)}
//
// RFC 4055 5 PKCS #1 Version 1.5
//
// sha256WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 11 }
//
// sha384WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 12 }
//
// sha512WithRSAEncryption OBJECT IDENTIFIER ::= { pkcs-1 13 }
//
// RFC 5758 3.1 DSA Signature Algorithms
//
// dsaWithSha256 OBJECT IDENTIFIER ::= {
// joint-iso-ccitt(2) country(16) us(840) organization(1) gov(101)
// csor(3) algorithms(4) id-dsa-with-sha2(3) 2}
//
// RFC 5758 3.2 ECDSA Signature Algorithm
//
// ecdsa-with-SHA256 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
// us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 2 }
//
// ecdsa-with-SHA384 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
// us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 3 }
//
// ecdsa-with-SHA512 OBJECT IDENTIFIER ::= { iso(1) member-body(2)
// us(840) ansi-X9-62(10045) signatures(4) ecdsa-with-SHA2(3) 4 }
//
// RFC 8410 3 Curve25519 and Curve448 Algorithm Identifiers
//
// id-Ed25519 OBJECT IDENTIFIER ::= { 1 3 101 112 }
var (
oidSignatureMD2WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 2}
oidSignatureMD5WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 4}
oidSignatureSHA1WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 5}
oidSignatureSHA256WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 11}
oidSignatureSHA384WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 12}
oidSignatureSHA512WithRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 13}
oidSignatureRSAPSS = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 10}
oidSignatureDSAWithSHA1 = asn1.ObjectIdentifier{1, 2, 840, 10040, 4, 3}
oidSignatureDSAWithSHA256 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 3, 2}
oidSignatureECDSAWithSHA1 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 1}
oidSignatureECDSAWithSHA256 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 2}
oidSignatureECDSAWithSHA384 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 3}
oidSignatureECDSAWithSHA512 = asn1.ObjectIdentifier{1, 2, 840, 10045, 4, 3, 4}
oidSignatureEd25519 = asn1.ObjectIdentifier{1, 3, 101, 112}
oidSHA256 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 1}
oidSHA384 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 2}
oidSHA512 = asn1.ObjectIdentifier{2, 16, 840, 1, 101, 3, 4, 2, 3}
oidMGF1 = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 8}
// oidISOSignatureSHA1WithRSA means the same as oidSignatureSHA1WithRSA
// but it's specified by ISO. Microsoft's makecert.exe has been known
// to produce certificates with this OID.
oidISOSignatureSHA1WithRSA = asn1.ObjectIdentifier{1, 3, 14, 3, 2, 29}
)
var signatureAlgorithmDetails = []struct {
algo SignatureAlgorithm
name string
oid asn1.ObjectIdentifier
pubKeyAlgo PublicKeyAlgorithm
hash crypto.Hash
}{
{MD2WithRSA, "MD2-RSA", oidSignatureMD2WithRSA, RSA, crypto.Hash(0) /* no value for MD2 */},
{MD5WithRSA, "MD5-RSA", oidSignatureMD5WithRSA, RSA, crypto.MD5},
{SHA1WithRSA, "SHA1-RSA", oidSignatureSHA1WithRSA, RSA, crypto.SHA1},
{SHA1WithRSA, "SHA1-RSA", oidISOSignatureSHA1WithRSA, RSA, crypto.SHA1},
{SHA256WithRSA, "SHA256-RSA", oidSignatureSHA256WithRSA, RSA, crypto.SHA256},
{SHA384WithRSA, "SHA384-RSA", oidSignatureSHA384WithRSA, RSA, crypto.SHA384},
{SHA512WithRSA, "SHA512-RSA", oidSignatureSHA512WithRSA, RSA, crypto.SHA512},
{SHA256WithRSAPSS, "SHA256-RSAPSS", oidSignatureRSAPSS, RSA, crypto.SHA256},
{SHA384WithRSAPSS, "SHA384-RSAPSS", oidSignatureRSAPSS, RSA, crypto.SHA384},
{SHA512WithRSAPSS, "SHA512-RSAPSS", oidSignatureRSAPSS, RSA, crypto.SHA512},
{DSAWithSHA1, "DSA-SHA1", oidSignatureDSAWithSHA1, DSA, crypto.SHA1},
{DSAWithSHA256, "DSA-SHA256", oidSignatureDSAWithSHA256, DSA, crypto.SHA256},
{ECDSAWithSHA1, "ECDSA-SHA1", oidSignatureECDSAWithSHA1, ECDSA, crypto.SHA1},
{ECDSAWithSHA256, "ECDSA-SHA256", oidSignatureECDSAWithSHA256, ECDSA, crypto.SHA256},
{ECDSAWithSHA384, "ECDSA-SHA384", oidSignatureECDSAWithSHA384, ECDSA, crypto.SHA384},
{ECDSAWithSHA512, "ECDSA-SHA512", oidSignatureECDSAWithSHA512, ECDSA, crypto.SHA512},
{PureEd25519, "Ed25519", oidSignatureEd25519, Ed25519, crypto.Hash(0) /* no pre-hashing */},
}
// hashToPSSParameters contains the DER encoded RSA PSS parameters for the
// SHA256, SHA384, and SHA512 hashes as defined in RFC 3447, Appendix A.2.3.
// The parameters contain the following values:
// - hashAlgorithm contains the associated hash identifier with NULL parameters
// - maskGenAlgorithm always contains the default mgf1SHA1 identifier
// - saltLength contains the length of the associated hash
// - trailerField always contains the default trailerFieldBC value
var hashToPSSParameters = map[crypto.Hash]asn1.RawValue{
crypto.SHA256: 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}},
crypto.SHA384: 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}},
crypto.SHA512: 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}},
}
// pssParameters reflects the parameters in an AlgorithmIdentifier that
// specifies RSA PSS. See RFC 3447, Appendix A.2.3.
type pssParameters struct {
// The following three fields are not marked as
// optional because the default values specify SHA-1,
// which is no longer suitable for use in signatures.
Hash pkix.AlgorithmIdentifier `asn1:"explicit,tag:0"`
MGF pkix.AlgorithmIdentifier `asn1:"explicit,tag:1"`
SaltLength int `asn1:"explicit,tag:2"`
TrailerField int `asn1:"optional,explicit,tag:3,default:1"`
}
func getSignatureAlgorithmFromAI(ai pkix.AlgorithmIdentifier) SignatureAlgorithm {
if ai.Algorithm.Equal(oidSignatureEd25519) {
// RFC 8410, Section 3
// > For all of the OIDs, the parameters MUST be absent.
if len(ai.Parameters.FullBytes) != 0 {
return UnknownSignatureAlgorithm
}
}
if !ai.Algorithm.Equal(oidSignatureRSAPSS) {
for _, details := range signatureAlgorithmDetails {
if ai.Algorithm.Equal(details.oid) {
return details.algo
}
}
return UnknownSignatureAlgorithm
}
// RSA PSS is special because it encodes important parameters
// in the Parameters.
var params pssParameters
if _, err := asn1.Unmarshal(ai.Parameters.FullBytes, ¶ms); err != nil {
return UnknownSignatureAlgorithm
}
var mgf1HashFunc pkix.AlgorithmIdentifier
if _, err := asn1.Unmarshal(params.MGF.Parameters.FullBytes, &mgf1HashFunc); err != nil {
return UnknownSignatureAlgorithm
}
// PSS is greatly overburdened with options. This code forces them into
// three buckets by requiring that the MGF1 hash function always match the
// message hash function (as recommended in RFC 3447, Section 8.1), that the
// salt length matches the hash length, and that the trailer field has the
// default value.
if (len(params.Hash.Parameters.FullBytes) != 0 && !bytes.Equal(params.Hash.Parameters.FullBytes, asn1.NullBytes)) ||
!params.MGF.Algorithm.Equal(oidMGF1) ||
!mgf1HashFunc.Algorithm.Equal(params.Hash.Algorithm) ||
(len(mgf1HashFunc.Parameters.FullBytes) != 0 && !bytes.Equal(mgf1HashFunc.Parameters.FullBytes, asn1.NullBytes)) ||
params.TrailerField != 1 {
return UnknownSignatureAlgorithm
}
switch {
case params.Hash.Algorithm.Equal(oidSHA256) && params.SaltLength == 32:
return SHA256WithRSAPSS
case params.Hash.Algorithm.Equal(oidSHA384) && params.SaltLength == 48:
return SHA384WithRSAPSS
case params.Hash.Algorithm.Equal(oidSHA512) && params.SaltLength == 64:
return SHA512WithRSAPSS
}
return UnknownSignatureAlgorithm
}
var (
// RFC 3279, 2.3 Public Key Algorithms
//
// pkcs-1 OBJECT IDENTIFIER ::== { iso(1) member-body(2) us(840)
// rsadsi(113549) pkcs(1) 1 }
//
// rsaEncryption OBJECT IDENTIFIER ::== { pkcs1-1 1 }
//
// id-dsa OBJECT IDENTIFIER ::== { iso(1) member-body(2) us(840)
// x9-57(10040) x9cm(4) 1 }
oidPublicKeyRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 1}
oidPublicKeyDSA = asn1.ObjectIdentifier{1, 2, 840, 10040, 4, 1}
// RFC 5480, 2.1.1 Unrestricted Algorithm Identifier and Parameters
//
// id-ecPublicKey OBJECT IDENTIFIER ::= {
// iso(1) member-body(2) us(840) ansi-X9-62(10045) keyType(2) 1 }
oidPublicKeyECDSA = asn1.ObjectIdentifier{1, 2, 840, 10045, 2, 1}
// RFC 8410, Section 3
//
// id-X25519 OBJECT IDENTIFIER ::= { 1 3 101 110 }
// id-Ed25519 OBJECT IDENTIFIER ::= { 1 3 101 112 }
oidPublicKeyX25519 = asn1.ObjectIdentifier{1, 3, 101, 110}
oidPublicKeyEd25519 = asn1.ObjectIdentifier{1, 3, 101, 112}
)
// getPublicKeyAlgorithmFromOID returns the exposed PublicKeyAlgorithm
// identifier for public key types supported in certificates and CSRs. Marshal
// and Parse functions may support a different set of public key types.
func getPublicKeyAlgorithmFromOID(oid asn1.ObjectIdentifier) PublicKeyAlgorithm {
switch {
case oid.Equal(oidPublicKeyRSA):
return RSA
case oid.Equal(oidPublicKeyDSA):
return DSA
case oid.Equal(oidPublicKeyECDSA):
return ECDSA
case oid.Equal(oidPublicKeyEd25519):
return Ed25519
}
return UnknownPublicKeyAlgorithm
}
// RFC 5480, 2.1.1.1. Named Curve
//
// secp224r1 OBJECT IDENTIFIER ::= {
// iso(1) identified-organization(3) certicom(132) curve(0) 33 }
//
// secp256r1 OBJECT IDENTIFIER ::= {
// iso(1) member-body(2) us(840) ansi-X9-62(10045) curves(3)
// prime(1) 7 }
//
// secp384r1 OBJECT IDENTIFIER ::= {
// iso(1) identified-organization(3) certicom(132) curve(0) 34 }
//
// secp521r1 OBJECT IDENTIFIER ::= {
// iso(1) identified-organization(3) certicom(132) curve(0) 35 }
//
// NB: secp256r1 is equivalent to prime256v1
var (
oidNamedCurveP224 = asn1.ObjectIdentifier{1, 3, 132, 0, 33}
oidNamedCurveP256 = asn1.ObjectIdentifier{1, 2, 840, 10045, 3, 1, 7}
oidNamedCurveP384 = asn1.ObjectIdentifier{1, 3, 132, 0, 34}
oidNamedCurveP521 = asn1.ObjectIdentifier{1, 3, 132, 0, 35}
)
func namedCurveFromOID(oid asn1.ObjectIdentifier) elliptic.Curve {
switch {
case oid.Equal(oidNamedCurveP224):
return elliptic.P224()
case oid.Equal(oidNamedCurveP256):
return elliptic.P256()
case oid.Equal(oidNamedCurveP384):
return elliptic.P384()
case oid.Equal(oidNamedCurveP521):
return elliptic.P521()
}
return nil
}
func oidFromNamedCurve(curve elliptic.Curve) (asn1.ObjectIdentifier, bool) {
switch curve {
case elliptic.P224():
return oidNamedCurveP224, true
case elliptic.P256():
return oidNamedCurveP256, true
case elliptic.P384():
return oidNamedCurveP384, true
case elliptic.P521():
return oidNamedCurveP521, true
}
return nil, false
}
func oidFromECDHCurve(curve ecdh.Curve) (asn1.ObjectIdentifier, bool) {
switch curve {
case ecdh.X25519():
return oidPublicKeyX25519, true
case ecdh.P256():
return oidNamedCurveP256, true
case ecdh.P384():
return oidNamedCurveP384, true
case ecdh.P521():
return oidNamedCurveP521, true
}
return nil, false
}
// KeyUsage represents the set of actions that are valid for a given key. It's
// a bitmap of the KeyUsage* constants.
type KeyUsage int
const (
KeyUsageDigitalSignature KeyUsage = 1 << iota
KeyUsageContentCommitment
KeyUsageKeyEncipherment
KeyUsageDataEncipherment
KeyUsageKeyAgreement
KeyUsageCertSign
KeyUsageCRLSign
KeyUsageEncipherOnly
KeyUsageDecipherOnly
)
// RFC 5280, 4.2.1.12 Extended Key Usage
//
// anyExtendedKeyUsage OBJECT IDENTIFIER ::= { id-ce-extKeyUsage 0 }
//
// id-kp OBJECT IDENTIFIER ::= { id-pkix 3 }
//
// id-kp-serverAuth OBJECT IDENTIFIER ::= { id-kp 1 }
// id-kp-clientAuth OBJECT IDENTIFIER ::= { id-kp 2 }
// id-kp-codeSigning OBJECT IDENTIFIER ::= { id-kp 3 }
// id-kp-emailProtection OBJECT IDENTIFIER ::= { id-kp 4 }
// id-kp-timeStamping OBJECT IDENTIFIER ::= { id-kp 8 }
// id-kp-OCSPSigning OBJECT IDENTIFIER ::= { id-kp 9 }
var (
oidExtKeyUsageAny = asn1.ObjectIdentifier{2, 5, 29, 37, 0}
oidExtKeyUsageServerAuth = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 1}
oidExtKeyUsageClientAuth = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 2}
oidExtKeyUsageCodeSigning = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 3}
oidExtKeyUsageEmailProtection = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 4}
oidExtKeyUsageIPSECEndSystem = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 5}
oidExtKeyUsageIPSECTunnel = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 6}
oidExtKeyUsageIPSECUser = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 7}
oidExtKeyUsageTimeStamping = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 8}
oidExtKeyUsageOCSPSigning = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 9}
oidExtKeyUsageMicrosoftServerGatedCrypto = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 10, 3, 3}
oidExtKeyUsageNetscapeServerGatedCrypto = asn1.ObjectIdentifier{2, 16, 840, 1, 113730, 4, 1}
oidExtKeyUsageMicrosoftCommercialCodeSigning = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 2, 1, 22}
oidExtKeyUsageMicrosoftKernelCodeSigning = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 61, 1, 1}
)
// ExtKeyUsage represents an extended set of actions that are valid for a given key.
// Each of the ExtKeyUsage* constants define a unique action.
type ExtKeyUsage int
const (
ExtKeyUsageAny ExtKeyUsage = iota
ExtKeyUsageServerAuth
ExtKeyUsageClientAuth
ExtKeyUsageCodeSigning
ExtKeyUsageEmailProtection
ExtKeyUsageIPSECEndSystem
ExtKeyUsageIPSECTunnel
ExtKeyUsageIPSECUser
ExtKeyUsageTimeStamping
ExtKeyUsageOCSPSigning
ExtKeyUsageMicrosoftServerGatedCrypto
ExtKeyUsageNetscapeServerGatedCrypto
ExtKeyUsageMicrosoftCommercialCodeSigning
ExtKeyUsageMicrosoftKernelCodeSigning
)
// extKeyUsageOIDs contains the mapping between an ExtKeyUsage and its OID.
var extKeyUsageOIDs = []struct {
extKeyUsage ExtKeyUsage
oid asn1.ObjectIdentifier
}{
{ExtKeyUsageAny, oidExtKeyUsageAny},
{ExtKeyUsageServerAuth, oidExtKeyUsageServerAuth},
{ExtKeyUsageClientAuth, oidExtKeyUsageClientAuth},
{ExtKeyUsageCodeSigning, oidExtKeyUsageCodeSigning},
{ExtKeyUsageEmailProtection, oidExtKeyUsageEmailProtection},
{ExtKeyUsageIPSECEndSystem, oidExtKeyUsageIPSECEndSystem},
{ExtKeyUsageIPSECTunnel, oidExtKeyUsageIPSECTunnel},
{ExtKeyUsageIPSECUser, oidExtKeyUsageIPSECUser},
{ExtKeyUsageTimeStamping, oidExtKeyUsageTimeStamping},
{ExtKeyUsageOCSPSigning, oidExtKeyUsageOCSPSigning},
{ExtKeyUsageMicrosoftServerGatedCrypto, oidExtKeyUsageMicrosoftServerGatedCrypto},
{ExtKeyUsageNetscapeServerGatedCrypto, oidExtKeyUsageNetscapeServerGatedCrypto},
{ExtKeyUsageMicrosoftCommercialCodeSigning, oidExtKeyUsageMicrosoftCommercialCodeSigning},
{ExtKeyUsageMicrosoftKernelCodeSigning, oidExtKeyUsageMicrosoftKernelCodeSigning},
}
func extKeyUsageFromOID(oid asn1.ObjectIdentifier) (eku ExtKeyUsage, ok bool) {
for _, pair := range extKeyUsageOIDs {
if oid.Equal(pair.oid) {
return pair.extKeyUsage, true
}
}
return
}
func oidFromExtKeyUsage(eku ExtKeyUsage) (oid asn1.ObjectIdentifier, ok bool) {
for _, pair := range extKeyUsageOIDs {
if eku == pair.extKeyUsage {
return pair.oid, true
}
}
return
}
// A Certificate represents an X.509 certificate.
type Certificate struct {
Raw []byte // Complete ASN.1 DER content (certificate, signature algorithm and signature).
RawTBSCertificate []byte // Certificate part of raw ASN.1 DER content.
RawSubjectPublicKeyInfo []byte // DER encoded SubjectPublicKeyInfo.
RawSubject []byte // DER encoded Subject
RawIssuer []byte // DER encoded Issuer
Signature []byte
SignatureAlgorithm SignatureAlgorithm
PublicKeyAlgorithm PublicKeyAlgorithm
PublicKey any
Version int
SerialNumber *big.Int
Issuer pkix.Name
Subject pkix.Name
NotBefore, NotAfter time.Time // Validity bounds.
KeyUsage KeyUsage
// Extensions contains raw X.509 extensions. When parsing certificates,
// this can be used to extract non-critical extensions that are not
// parsed by this package. When marshaling certificates, the Extensions
// field is ignored, see ExtraExtensions.
Extensions []pkix.Extension
// ExtraExtensions contains extensions to be copied, raw, into any
// marshaled certificates. Values override any extensions that would
// otherwise be produced based on the other fields. The ExtraExtensions
// field is not populated when parsing certificates, see Extensions.
ExtraExtensions []pkix.Extension
// UnhandledCriticalExtensions contains a list of extension IDs that
// were not (fully) processed when parsing. Verify will fail if this
// slice is non-empty, unless verification is delegated to an OS
// library which understands all the critical extensions.
//
// Users can access these extensions using Extensions and can remove
// elements from this slice if they believe that they have been
// handled.
UnhandledCriticalExtensions []asn1.ObjectIdentifier
ExtKeyUsage []ExtKeyUsage // Sequence of extended key usages.
UnknownExtKeyUsage []asn1.ObjectIdentifier // Encountered extended key usages unknown to this package.
// BasicConstraintsValid indicates whether IsCA, MaxPathLen,
// and MaxPathLenZero are valid.
BasicConstraintsValid bool
IsCA bool
// MaxPathLen and MaxPathLenZero indicate the presence and
// value of the BasicConstraints' "pathLenConstraint".
//
// When parsing a certificate, a positive non-zero MaxPathLen
// means that the field was specified, -1 means it was unset,
// and MaxPathLenZero being true mean that the field was
// explicitly set to zero. The case of MaxPathLen==0 with MaxPathLenZero==false
// should be treated equivalent to -1 (unset).
//
// When generating a certificate, an unset pathLenConstraint
// can be requested with either MaxPathLen == -1 or using the
// zero value for both MaxPathLen and MaxPathLenZero.
MaxPathLen int
// MaxPathLenZero indicates that BasicConstraintsValid==true
// and MaxPathLen==0 should be interpreted as an actual
// maximum path length of zero. Otherwise, that combination is
// interpreted as MaxPathLen not being set.
MaxPathLenZero bool
SubjectKeyId []byte
AuthorityKeyId []byte
// RFC 5280, 4.2.2.1 (Authority Information Access)
OCSPServer []string
IssuingCertificateURL []string
// Subject Alternate Name values. (Note that these values may not be valid
// if invalid values were contained within a parsed certificate. For
// example, an element of DNSNames may not be a valid DNS domain name.)
DNSNames []string
EmailAddresses []string
IPAddresses []net.IP
URIs []*url.URL
// Name constraints
PermittedDNSDomainsCritical bool // if true then the name constraints are marked critical.
PermittedDNSDomains []string
ExcludedDNSDomains []string
PermittedIPRanges []*net.IPNet
ExcludedIPRanges []*net.IPNet
PermittedEmailAddresses []string
ExcludedEmailAddresses []string
PermittedURIDomains []string
ExcludedURIDomains []string
// CRL Distribution Points
CRLDistributionPoints []string
// PolicyIdentifiers contains asn1.ObjectIdentifiers, the components
// of which are limited to int32. If a certificate contains a policy which
// cannot be represented by asn1.ObjectIdentifier, it will not be included in
// PolicyIdentifiers, but will be present in Policies, which contains all parsed
// policy OIDs.
PolicyIdentifiers []asn1.ObjectIdentifier
// Policies contains all policy identifiers included in the certificate.
Policies []OID
}
// ErrUnsupportedAlgorithm results from attempting to perform an operation that
// involves algorithms that are not currently implemented.
var ErrUnsupportedAlgorithm = errors.New("x509: cannot verify signature: algorithm unimplemented")
// An InsecureAlgorithmError indicates that the [SignatureAlgorithm] used to
// generate the signature is not secure, and the signature has been rejected.
//
// To temporarily restore support for SHA-1 signatures, include the value
// "x509sha1=1" in the GODEBUG environment variable. Note that this option will
// be removed in a future release.
type InsecureAlgorithmError SignatureAlgorithm
func (e InsecureAlgorithmError) Error() string {
var override string
if SignatureAlgorithm(e) == SHA1WithRSA || SignatureAlgorithm(e) == ECDSAWithSHA1 {
override = " (temporarily override with GODEBUG=x509sha1=1)"
}
return fmt.Sprintf("x509: cannot verify signature: insecure algorithm %v", SignatureAlgorithm(e)) + override
}
// ConstraintViolationError results when a requested usage is not permitted by
// a certificate. For example: checking a signature when the public key isn't a
// certificate signing key.
type ConstraintViolationError struct{}
func (ConstraintViolationError) Error() string {
return "x509: invalid signature: parent certificate cannot sign this kind of certificate"
}
func (c *Certificate) Equal(other *Certificate) bool {
if c == nil || other == nil {
return c == other
}
return bytes.Equal(c.Raw, other.Raw)
}
func (c *Certificate) hasSANExtension() bool {
return oidInExtensions(oidExtensionSubjectAltName, c.Extensions)
}
// CheckSignatureFrom verifies that the signature on c is a valid signature from parent.
//
// This is a low-level API that performs very limited checks, and not a full
// path verifier. Most users should use [Certificate.Verify] instead.
func (c *Certificate) CheckSignatureFrom(parent *Certificate) error {
// RFC 5280, 4.2.1.9:
// "If the basic constraints extension is not present in a version 3
// certificate, or the extension is present but the cA boolean is not
// asserted, then the certified public key MUST NOT be used to verify
// certificate signatures."
if parent.Version == 3 && !parent.BasicConstraintsValid ||
parent.BasicConstraintsValid && !parent.IsCA {
return ConstraintViolationError{}
}
if parent.KeyUsage != 0 && parent.KeyUsage&KeyUsageCertSign == 0 {
return ConstraintViolationError{}
}
if parent.PublicKeyAlgorithm == UnknownPublicKeyAlgorithm {
return ErrUnsupportedAlgorithm
}
return checkSignature(c.SignatureAlgorithm, c.RawTBSCertificate, c.Signature, parent.PublicKey, false)
}
// CheckSignature verifies that signature is a valid signature over signed from
// c's public key.
//
// This is a low-level API that performs no validity checks on the certificate.
//
// [MD5WithRSA] signatures are rejected, while [SHA1WithRSA] and [ECDSAWithSHA1]
// signatures are currently accepted.
func (c *Certificate) CheckSignature(algo SignatureAlgorithm, signed, signature []byte) error {
return checkSignature(algo, signed, signature, c.PublicKey, true)
}
func (c *Certificate) hasNameConstraints() bool {
return oidInExtensions(oidExtensionNameConstraints, c.Extensions)
}
func (c *Certificate) getSANExtension() []byte {
for _, e := range c.Extensions {
if e.Id.Equal(oidExtensionSubjectAltName) {
return e.Value
}
}
return nil
}
func signaturePublicKeyAlgoMismatchError(expectedPubKeyAlgo PublicKeyAlgorithm, pubKey any) error {
return fmt.Errorf("x509: signature algorithm specifies an %s public key, but have public key of type %T", expectedPubKeyAlgo.String(), pubKey)
}
var x509sha1 = godebug.New("x509sha1")
// checkSignature verifies that signature is a valid signature over signed from
// a crypto.PublicKey.
func checkSignature(algo SignatureAlgorithm, signed, signature []byte, publicKey crypto.PublicKey, allowSHA1 bool) (err error) {
var hashType crypto.Hash
var pubKeyAlgo PublicKeyAlgorithm
for _, details := range signatureAlgorithmDetails {
if details.algo == algo {
hashType = details.hash
pubKeyAlgo = details.pubKeyAlgo
break
}
}
switch hashType {
case crypto.Hash(0):
if pubKeyAlgo != Ed25519 {
return ErrUnsupportedAlgorithm
}
case crypto.MD5:
return InsecureAlgorithmError(algo)
case crypto.SHA1:
// SHA-1 signatures are mostly disabled. See go.dev/issue/41682.
if !allowSHA1 {
if x509sha1.Value() != "1" {
return InsecureAlgorithmError(algo)
}
x509sha1.IncNonDefault()
}
fallthrough
default:
if !hashType.Available() {
return ErrUnsupportedAlgorithm
}
h := hashType.New()
h.Write(signed)
signed = h.Sum(nil)
}
switch pub := publicKey.(type) {
case *rsa.PublicKey:
if pubKeyAlgo != RSA {
return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
}
if algo.isRSAPSS() {
return rsa.VerifyPSS(pub, hashType, signed, signature, &rsa.PSSOptions{SaltLength: rsa.PSSSaltLengthEqualsHash})
} else {
return rsa.VerifyPKCS1v15(pub, hashType, signed, signature)
}
case *ecdsa.PublicKey:
if pubKeyAlgo != ECDSA {
return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
}
if !ecdsa.VerifyASN1(pub, signed, signature) {
return errors.New("x509: ECDSA verification failure")
}
return
case ed25519.PublicKey:
if pubKeyAlgo != Ed25519 {
return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
}
if !ed25519.Verify(pub, signed, signature) {
return errors.New("x509: Ed25519 verification failure")
}
return
}
return ErrUnsupportedAlgorithm
}
// CheckCRLSignature checks that the signature in crl is from c.
//
// Deprecated: Use [RevocationList.CheckSignatureFrom] instead.
func (c *Certificate) CheckCRLSignature(crl *pkix.CertificateList) error {
algo := getSignatureAlgorithmFromAI(crl.SignatureAlgorithm)
return c.CheckSignature(algo, crl.TBSCertList.Raw, crl.SignatureValue.RightAlign())
}
type UnhandledCriticalExtension struct{}
func (h UnhandledCriticalExtension) Error() string {
return "x509: unhandled critical extension"
}
type basicConstraints struct {
IsCA bool `asn1:"optional"`
MaxPathLen int `asn1:"optional,default:-1"`
}
// RFC 5280 4.2.1.4
type policyInformation struct {
Policy asn1.ObjectIdentifier
// policyQualifiers omitted
}
const (
nameTypeEmail = 1
nameTypeDNS = 2
nameTypeURI = 6
nameTypeIP = 7
)
// RFC 5280, 4.2.2.1
type authorityInfoAccess struct {
Method asn1.ObjectIdentifier
Location asn1.RawValue
}
// RFC 5280, 4.2.1.14
type distributionPoint struct {
DistributionPoint distributionPointName `asn1:"optional,tag:0"`
Reason asn1.BitString `asn1:"optional,tag:1"`
CRLIssuer asn1.RawValue `asn1:"optional,tag:2"`
}
type distributionPointName struct {
FullName []asn1.RawValue `asn1:"optional,tag:0"`
RelativeName pkix.RDNSequence `asn1:"optional,tag:1"`
}