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x509.go
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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 parses X.509-encoded keys and certificates.
//
// On UNIX systems the environment variables SSL_CERT_FILE and SSL_CERT_DIR
// can be used to override the system default locations for the SSL certificate
// file and SSL certificate files directory, respectively.
//
// This is a fork of the go library crypto/x509 package, it's more relaxed
// about certificates that it'll accept, and exports the TBSCertificate
// structure.
package x509
import (
"bytes"
"crypto"
"crypto/dsa"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rsa"
_ "crypto/sha1"
_ "crypto/sha256"
_ "crypto/sha512"
"encoding/pem"
"errors"
"fmt"
"io"
"math/big"
"net"
"net/url"
"strconv"
"strings"
"time"
"unicode/utf8"
cryptobyte_asn1 "golang.org/x/crypto/cryptobyte/asn1"
"github.com/google/certificate-transparency-go/asn1"
"github.com/google/certificate-transparency-go/tls"
"github.com/google/certificate-transparency-go/x509/pkix"
"golang.org/x/crypto/cryptobyte"
)
// pkixPublicKey reflects a PKIX public key structure. See SubjectPublicKeyInfo
// in RFC 3280.
type pkixPublicKey struct {
Algo pkix.AlgorithmIdentifier
BitString asn1.BitString
}
// ParsePKIXPublicKey parses a DER encoded public key. These values are
// typically found in PEM blocks with "BEGIN PUBLIC KEY".
//
// Supported key types include RSA, DSA, and ECDSA. Unknown key
// types result in an error.
//
// On success, pub will be of type *rsa.PublicKey, *dsa.PublicKey,
// or *ecdsa.PublicKey.
func ParsePKIXPublicKey(derBytes []byte) (pub interface{}, err error) {
var pki publicKeyInfo
if rest, err := asn1.Unmarshal(derBytes, &pki); err != nil {
return nil, err
} else if len(rest) != 0 {
return nil, errors.New("x509: trailing data after ASN.1 of public-key")
}
algo := getPublicKeyAlgorithmFromOID(pki.Algorithm.Algorithm)
if algo == UnknownPublicKeyAlgorithm {
return nil, errors.New("x509: unknown public key algorithm")
}
return parsePublicKey(algo, &pki)
}
func marshalPublicKey(pub interface{}) (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
// https://tools.ietf.org/html/rfc3279#section-2.3.1.
publicKeyAlgorithm.Parameters = asn1.NullRawValue
case *ecdsa.PublicKey:
publicKeyBytes = elliptic.Marshal(pub.Curve, pub.X, pub.Y)
oid, ok := OIDFromNamedCurve(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{}, errors.New("x509: only RSA and ECDSA public keys supported")
}
return publicKeyBytes, publicKeyAlgorithm, nil
}
// MarshalPKIXPublicKey serialises a public key to DER-encoded PKIX format.
func MarshalPKIXPublicKey(pub interface{}) ([]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 {
Raw asn1.RawContent
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:"optional,explicit,tag:3"`
}
type dsaAlgorithmParameters struct {
P, Q, G *big.Int
}
type dsaSignature struct {
R, S *big.Int
}
type ecdsaSignature dsaSignature
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"`
}
// SignatureAlgorithm indicates the algorithm used to sign a certificate.
type SignatureAlgorithm int
// SignatureAlgorithm values:
const (
UnknownSignatureAlgorithm SignatureAlgorithm = iota
MD2WithRSA
MD5WithRSA
SHA1WithRSA
SHA256WithRSA
SHA384WithRSA
SHA512WithRSA
DSAWithSHA1
DSAWithSHA256
ECDSAWithSHA1
ECDSAWithSHA256
ECDSAWithSHA384
ECDSAWithSHA512
SHA256WithRSAPSS
SHA384WithRSAPSS
SHA512WithRSAPSS
)
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))
}
// PublicKeyAlgorithm indicates the algorithm used for a certificate's public key.
type PublicKeyAlgorithm int
// PublicKeyAlgorithm values:
const (
UnknownPublicKeyAlgorithm PublicKeyAlgorithm = iota
RSA
DSA
ECDSA
)
var publicKeyAlgoName = [...]string{
RSA: "RSA",
DSA: "DSA",
ECDSA: "ECDSA",
}
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 }
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}
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},
}
// pssParameters reflects the parameters in an AlgorithmIdentifier that
// specifies RSA PSS. See https://tools.ietf.org/html/rfc3447#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"`
}
// rsaPSSParameters returns an asn1.RawValue suitable for use as the Parameters
// in an AlgorithmIdentifier that specifies RSA PSS.
func rsaPSSParameters(hashFunc crypto.Hash) asn1.RawValue {
var hashOID asn1.ObjectIdentifier
switch hashFunc {
case crypto.SHA256:
hashOID = oidSHA256
case crypto.SHA384:
hashOID = oidSHA384
case crypto.SHA512:
hashOID = oidSHA512
}
params := pssParameters{
Hash: pkix.AlgorithmIdentifier{
Algorithm: hashOID,
Parameters: asn1.NullRawValue,
},
MGF: pkix.AlgorithmIdentifier{
Algorithm: oidMGF1,
},
SaltLength: hashFunc.Size(),
TrailerField: 1,
}
mgf1Params := pkix.AlgorithmIdentifier{
Algorithm: hashOID,
Parameters: asn1.NullRawValue,
}
var err error
params.MGF.Parameters.FullBytes, err = asn1.Marshal(mgf1Params)
if err != nil {
panic(err)
}
serialized, err := asn1.Marshal(params)
if err != nil {
panic(err)
}
return asn1.RawValue{FullBytes: serialized}
}
// SignatureAlgorithmFromAI converts an PKIX algorithm identifier to the
// equivalent local constant.
func SignatureAlgorithmFromAI(ai pkix.AlgorithmIdentifier) SignatureAlgorithm {
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
// https://tools.ietf.org/html/rfc3447#section-8.1), that the
// salt length matches the hash length, and that the trailer
// field has the default value.
if !bytes.Equal(params.Hash.Parameters.FullBytes, asn1.NullBytes) ||
!params.MGF.Algorithm.Equal(oidMGF1) ||
!mgf1HashFunc.Algorithm.Equal(params.Hash.Algorithm) ||
!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
}
// 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 }
//
// 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 }
var (
OIDPublicKeyRSA = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 1}
OIDPublicKeyDSA = asn1.ObjectIdentifier{1, 2, 840, 10040, 4, 1}
OIDPublicKeyECDSA = asn1.ObjectIdentifier{1, 2, 840, 10045, 2, 1}
OIDPublicKeyRSAObsolete = asn1.ObjectIdentifier{2, 5, 8, 1, 1}
)
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
}
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
}
// OIDFromNamedCurve returns the OID used to specify the use of the given
// elliptic curve.
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
}
// KeyUsage represents the set of actions that are valid for a given key. It's
// a bitmap of the KeyUsage* constants.
type KeyUsage int
// KeyUsage values:
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}
// RFC 6962 s3.1
oidExtKeyUsageCertificateTransparency = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 11129, 2, 4, 4}
)
// 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
// ExtKeyUsage values:
const (
ExtKeyUsageAny ExtKeyUsage = iota
ExtKeyUsageServerAuth
ExtKeyUsageClientAuth
ExtKeyUsageCodeSigning
ExtKeyUsageEmailProtection
ExtKeyUsageIPSECEndSystem
ExtKeyUsageIPSECTunnel
ExtKeyUsageIPSECUser
ExtKeyUsageTimeStamping
ExtKeyUsageOCSPSigning
ExtKeyUsageMicrosoftServerGatedCrypto
ExtKeyUsageNetscapeServerGatedCrypto
ExtKeyUsageMicrosoftCommercialCodeSigning
ExtKeyUsageMicrosoftKernelCodeSigning
ExtKeyUsageCertificateTransparency
)
// 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},
{ExtKeyUsageCertificateTransparency, oidExtKeyUsageCertificateTransparency},
}
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
}
// SerializedSCT represents a single TLS-encoded signed certificate timestamp, from RFC6962 s3.3.
type SerializedSCT struct {
Val []byte `tls:"minlen:1,maxlen:65535"`
}
// SignedCertificateTimestampList is a list of signed certificate timestamps, from RFC6962 s3.3.
type SignedCertificateTimestampList struct {
SCTList []SerializedSCT `tls:"minlen:1,maxlen:65335"`
}
// 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 interface{}
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 []asn1.ObjectIdentifier
// Certificate Transparency SCT extension contents; this is a TLS-encoded
// SignedCertificateTimestampList (RFC 6962 s3.3).
RawSCT []byte
SCTList SignedCertificateTimestampList
}
// 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")
// InsecureAlgorithmError results when the signature algorithm for a certificate
// is known to be insecure.
type InsecureAlgorithmError SignatureAlgorithm
func (e InsecureAlgorithmError) Error() string {
return fmt.Sprintf("x509: cannot verify signature: insecure algorithm %v", SignatureAlgorithm(e))
}
// 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"
}
// Equal indicates whether two Certificate objects are equal (by comparing their
// DER-encoded values).
func (c *Certificate) Equal(other *Certificate) bool {
return bytes.Equal(c.Raw, other.Raw)
}
// IsPrecertificate checks whether the certificate is a precertificate, by
// checking for the presence of the CT Poison extension.
func (c *Certificate) IsPrecertificate() bool {
if c == nil {
return false
}
for _, ext := range c.Extensions {
if ext.Id.Equal(OIDExtensionCTPoison) {
return true
}
}
return false
}
func (c *Certificate) hasSANExtension() bool {
return oidInExtensions(OIDExtensionSubjectAltName, c.Extensions)
}
// Entrust have a broken root certificate (CN=Entrust.net Certification
// Authority (2048)) which isn't marked as a CA certificate and is thus invalid
// according to PKIX.
// We recognise this certificate by its SubjectPublicKeyInfo and exempt it
// from the Basic Constraints requirement.
// See http://www.entrust.net/knowledge-base/technote.cfm?tn=7869
//
// TODO(agl): remove this hack once their reissued root is sufficiently
// widespread.
var entrustBrokenSPKI = []byte{
0x30, 0x82, 0x01, 0x22, 0x30, 0x0d, 0x06, 0x09,
0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x01, 0x01,
0x01, 0x05, 0x00, 0x03, 0x82, 0x01, 0x0f, 0x00,
0x30, 0x82, 0x01, 0x0a, 0x02, 0x82, 0x01, 0x01,
0x00, 0x97, 0xa3, 0x2d, 0x3c, 0x9e, 0xde, 0x05,
0xda, 0x13, 0xc2, 0x11, 0x8d, 0x9d, 0x8e, 0xe3,
0x7f, 0xc7, 0x4b, 0x7e, 0x5a, 0x9f, 0xb3, 0xff,
0x62, 0xab, 0x73, 0xc8, 0x28, 0x6b, 0xba, 0x10,
0x64, 0x82, 0x87, 0x13, 0xcd, 0x57, 0x18, 0xff,
0x28, 0xce, 0xc0, 0xe6, 0x0e, 0x06, 0x91, 0x50,
0x29, 0x83, 0xd1, 0xf2, 0xc3, 0x2a, 0xdb, 0xd8,
0xdb, 0x4e, 0x04, 0xcc, 0x00, 0xeb, 0x8b, 0xb6,
0x96, 0xdc, 0xbc, 0xaa, 0xfa, 0x52, 0x77, 0x04,
0xc1, 0xdb, 0x19, 0xe4, 0xae, 0x9c, 0xfd, 0x3c,
0x8b, 0x03, 0xef, 0x4d, 0xbc, 0x1a, 0x03, 0x65,
0xf9, 0xc1, 0xb1, 0x3f, 0x72, 0x86, 0xf2, 0x38,
0xaa, 0x19, 0xae, 0x10, 0x88, 0x78, 0x28, 0xda,
0x75, 0xc3, 0x3d, 0x02, 0x82, 0x02, 0x9c, 0xb9,
0xc1, 0x65, 0x77, 0x76, 0x24, 0x4c, 0x98, 0xf7,
0x6d, 0x31, 0x38, 0xfb, 0xdb, 0xfe, 0xdb, 0x37,
0x02, 0x76, 0xa1, 0x18, 0x97, 0xa6, 0xcc, 0xde,
0x20, 0x09, 0x49, 0x36, 0x24, 0x69, 0x42, 0xf6,
0xe4, 0x37, 0x62, 0xf1, 0x59, 0x6d, 0xa9, 0x3c,
0xed, 0x34, 0x9c, 0xa3, 0x8e, 0xdb, 0xdc, 0x3a,
0xd7, 0xf7, 0x0a, 0x6f, 0xef, 0x2e, 0xd8, 0xd5,
0x93, 0x5a, 0x7a, 0xed, 0x08, 0x49, 0x68, 0xe2,
0x41, 0xe3, 0x5a, 0x90, 0xc1, 0x86, 0x55, 0xfc,
0x51, 0x43, 0x9d, 0xe0, 0xb2, 0xc4, 0x67, 0xb4,
0xcb, 0x32, 0x31, 0x25, 0xf0, 0x54, 0x9f, 0x4b,
0xd1, 0x6f, 0xdb, 0xd4, 0xdd, 0xfc, 0xaf, 0x5e,
0x6c, 0x78, 0x90, 0x95, 0xde, 0xca, 0x3a, 0x48,
0xb9, 0x79, 0x3c, 0x9b, 0x19, 0xd6, 0x75, 0x05,
0xa0, 0xf9, 0x88, 0xd7, 0xc1, 0xe8, 0xa5, 0x09,
0xe4, 0x1a, 0x15, 0xdc, 0x87, 0x23, 0xaa, 0xb2,
0x75, 0x8c, 0x63, 0x25, 0x87, 0xd8, 0xf8, 0x3d,
0xa6, 0xc2, 0xcc, 0x66, 0xff, 0xa5, 0x66, 0x68,
0x55, 0x02, 0x03, 0x01, 0x00, 0x01,
}
// CheckSignatureFrom verifies that the signature on c is a valid signature
// from parent.
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."
// (except for Entrust, see comment above entrustBrokenSPKI)
if (parent.Version == 3 && !parent.BasicConstraintsValid ||
parent.BasicConstraintsValid && !parent.IsCA) &&
!bytes.Equal(c.RawSubjectPublicKeyInfo, entrustBrokenSPKI) {
return ConstraintViolationError{}
}
if parent.KeyUsage != 0 && parent.KeyUsage&KeyUsageCertSign == 0 {
return ConstraintViolationError{}
}
if parent.PublicKeyAlgorithm == UnknownPublicKeyAlgorithm {
return ErrUnsupportedAlgorithm
}
// TODO(agl): don't ignore the path length constraint.
return parent.CheckSignature(c.SignatureAlgorithm, c.RawTBSCertificate, c.Signature)
}
// CheckSignature verifies that signature is a valid signature over signed from
// c's public key.
func (c *Certificate) CheckSignature(algo SignatureAlgorithm, signed, signature []byte) error {
return checkSignature(algo, signed, signature, c.PublicKey)
}
func (c *Certificate) hasNameConstraints() bool {
for _, e := range c.Extensions {
if len(e.Id) == 4 && e.Id[0] == OIDExtensionNameConstraints[0] && e.Id[1] == OIDExtensionNameConstraints[1] && e.Id[2] == OIDExtensionNameConstraints[2] && e.Id[3] == OIDExtensionNameConstraints[3] {
return true
}
}
return false
}
func (c *Certificate) getSANExtension() ([]byte, bool) {
for _, e := range c.Extensions {
if len(e.Id) == 4 && e.Id[0] == OIDExtensionSubjectAltName[0] && e.Id[1] == OIDExtensionSubjectAltName[1] && e.Id[2] == OIDExtensionSubjectAltName[2] && e.Id[3] == OIDExtensionSubjectAltName[3] {
return e.Value, true
}
}
return nil, false
}
func signaturePublicKeyAlgoMismatchError(expectedPubKeyAlgo PublicKeyAlgorithm, pubKey interface{}) error {
return fmt.Errorf("x509: signature algorithm specifies an %s public key, but have public key of type %T", expectedPubKeyAlgo.String(), pubKey)
}
// CheckSignature verifies that signature is a valid signature over signed from
// a crypto.PublicKey.
func checkSignature(algo SignatureAlgorithm, signed, signature []byte, publicKey crypto.PublicKey) (err error) {
var hashType crypto.Hash
var pubKeyAlgo PublicKeyAlgorithm
for _, details := range signatureAlgorithmDetails {
if details.algo == algo {
hashType = details.hash
pubKeyAlgo = details.pubKeyAlgo
}
}
switch hashType {
case crypto.Hash(0):
return ErrUnsupportedAlgorithm
case crypto.MD5:
return InsecureAlgorithmError(algo)
}
if !hashType.Available() {
return ErrUnsupportedAlgorithm
}
h := hashType.New()
h.Write(signed)
digest := 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, digest, signature, &rsa.PSSOptions{SaltLength: rsa.PSSSaltLengthEqualsHash})
} else {
return rsa.VerifyPKCS1v15(pub, hashType, digest, signature)
}
case *dsa.PublicKey:
if pubKeyAlgo != DSA {
return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
}
dsaSig := new(dsaSignature)
if rest, err := asn1.Unmarshal(signature, dsaSig); err != nil {
return err
} else if len(rest) != 0 {
return errors.New("x509: trailing data after DSA signature")
}
if dsaSig.R.Sign() <= 0 || dsaSig.S.Sign() <= 0 {
return errors.New("x509: DSA signature contained zero or negative values")
}
if !dsa.Verify(pub, digest, dsaSig.R, dsaSig.S) {
return errors.New("x509: DSA verification failure")
}
return
case *ecdsa.PublicKey:
if pubKeyAlgo != ECDSA {
return signaturePublicKeyAlgoMismatchError(pubKeyAlgo, pub)
}
ecdsaSig := new(ecdsaSignature)
if rest, err := asn1.Unmarshal(signature, ecdsaSig); err != nil {
return err
} else if len(rest) != 0 {
return errors.New("x509: trailing data after ECDSA signature")
}
if ecdsaSig.R.Sign() <= 0 || ecdsaSig.S.Sign() <= 0 {
return errors.New("x509: ECDSA signature contained zero or negative values")
}
if !ecdsa.Verify(pub, digest, ecdsaSig.R, ecdsaSig.S) {
return errors.New("x509: ECDSA verification failure")
}
return
}
return ErrUnsupportedAlgorithm
}
// CheckCRLSignature checks that the signature in crl is from c.
func (c *Certificate) CheckCRLSignature(crl *pkix.CertificateList) error {
algo := SignatureAlgorithmFromAI(crl.SignatureAlgorithm)