/
x509.go
2080 lines (1820 loc) · 63 KB
/
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.
package x509
import (
"bytes"
"crypto"
"crypto/dsa"
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rsa"
_ "crypto/sha1"
_ "crypto/sha256"
_ "crypto/sha512"
"crypto/x509/pkix"
"encoding/asn1"
"encoding/pem"
"errors"
"fmt"
"io"
"math/big"
"net"
"strconv"
"time"
)
// 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(rsaPublicKey{
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 technically
// superfluous, but most other code includes it and, by
// doing this, we match their public key hashes.
publicKeyAlgorithm.Parameters = asn1.RawValue{
Tag: 5,
}
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"`
}
type SignatureAlgorithm int
const (
UnknownSignatureAlgorithm SignatureAlgorithm = iota
MD2WithRSA
MD5WithRSA
SHA1WithRSA
SHA256WithRSA
SHA384WithRSA
SHA512WithRSA
DSAWithSHA1
DSAWithSHA256
ECDSAWithSHA1
ECDSAWithSHA256
ECDSAWithSHA384
ECDSAWithSHA512
)
var algoName = [...]string{
MD2WithRSA: "MD2-RSA",
MD5WithRSA: "MD5-RSA",
SHA1WithRSA: "SHA1-RSA",
SHA256WithRSA: "SHA256-RSA",
SHA384WithRSA: "SHA384-RSA",
SHA512WithRSA: "SHA512-RSA",
DSAWithSHA1: "DSA-SHA1",
DSAWithSHA256: "DSA-SHA256",
ECDSAWithSHA1: "ECDSA-SHA1",
ECDSAWithSHA256: "ECDSA-SHA256",
ECDSAWithSHA384: "ECDSA-SHA384",
ECDSAWithSHA512: "ECDSA-SHA512",
}
func (algo SignatureAlgorithm) String() string {
if 0 < algo && int(algo) < len(algoName) {
return algoName[algo]
}
return strconv.Itoa(int(algo))
}
type PublicKeyAlgorithm int
const (
UnknownPublicKeyAlgorithm PublicKeyAlgorithm = iota
RSA
DSA
ECDSA
)
// 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}
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}
)
var signatureAlgorithmDetails = []struct {
algo SignatureAlgorithm
oid asn1.ObjectIdentifier
pubKeyAlgo PublicKeyAlgorithm
hash crypto.Hash
}{
{MD2WithRSA, oidSignatureMD2WithRSA, RSA, crypto.Hash(0) /* no value for MD2 */},
{MD5WithRSA, oidSignatureMD5WithRSA, RSA, crypto.MD5},
{SHA1WithRSA, oidSignatureSHA1WithRSA, RSA, crypto.SHA1},
{SHA256WithRSA, oidSignatureSHA256WithRSA, RSA, crypto.SHA256},
{SHA384WithRSA, oidSignatureSHA384WithRSA, RSA, crypto.SHA384},
{SHA512WithRSA, oidSignatureSHA512WithRSA, RSA, crypto.SHA512},
{DSAWithSHA1, oidSignatureDSAWithSHA1, DSA, crypto.SHA1},
{DSAWithSHA256, oidSignatureDSAWithSHA256, DSA, crypto.SHA256},
{ECDSAWithSHA1, oidSignatureECDSAWithSHA1, ECDSA, crypto.SHA1},
{ECDSAWithSHA256, oidSignatureECDSAWithSHA256, ECDSA, crypto.SHA256},
{ECDSAWithSHA384, oidSignatureECDSAWithSHA384, ECDSA, crypto.SHA384},
{ECDSAWithSHA512, oidSignatureECDSAWithSHA512, ECDSA, crypto.SHA512},
}
func getSignatureAlgorithmFromOID(oid asn1.ObjectIdentifier) SignatureAlgorithm {
for _, details := range signatureAlgorithmDetails {
if oid.Equal(details.oid) {
return details.algo
}
}
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}
)
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
}
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
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}
)
// 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
)
// 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},
}
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 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 bool // if true then the next two fields are valid.
IsCA bool
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
DNSNames []string
EmailAddresses []string
IPAddresses []net.IP
// Name constraints
PermittedDNSDomainsCritical bool // if true then the name constraints are marked critical.
PermittedDNSDomains []string
// CRL Distribution Points
CRLDistributionPoints []string
PolicyIdentifiers []asn1.ObjectIdentifier
}
// 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
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"
}
func (c *Certificate) Equal(other *Certificate) bool {
return bytes.Equal(c.Raw, other.Raw)
}
// 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)
}
// 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
switch algo {
case SHA1WithRSA, DSAWithSHA1, ECDSAWithSHA1:
hashType = crypto.SHA1
case SHA256WithRSA, DSAWithSHA256, ECDSAWithSHA256:
hashType = crypto.SHA256
case SHA384WithRSA, ECDSAWithSHA384:
hashType = crypto.SHA384
case SHA512WithRSA, ECDSAWithSHA512:
hashType = crypto.SHA512
case MD2WithRSA, MD5WithRSA:
return InsecureAlgorithmError(algo)
default:
return ErrUnsupportedAlgorithm
}
if !hashType.Available() {
return ErrUnsupportedAlgorithm
}
h := hashType.New()
h.Write(signed)
digest := h.Sum(nil)
switch pub := publicKey.(type) {
case *rsa.PublicKey:
return rsa.VerifyPKCS1v15(pub, hashType, digest, signature)
case *dsa.PublicKey:
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:
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 := getSignatureAlgorithmFromOID(crl.SignatureAlgorithm.Algorithm)
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
}
// RFC 5280, 4.2.1.10
type nameConstraints struct {
Permitted []generalSubtree `asn1:"optional,tag:0"`
Excluded []generalSubtree `asn1:"optional,tag:1"`
}
type generalSubtree struct {
Name string `asn1:"tag:2,optional,ia5"`
}
// 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"`
}
func parsePublicKey(algo PublicKeyAlgorithm, keyData *publicKeyInfo) (interface{}, error) {
asn1Data := keyData.PublicKey.RightAlign()
switch algo {
case RSA:
p := new(rsaPublicKey)
rest, err := asn1.Unmarshal(asn1Data, p)
if err != nil {
return nil, err
}
if len(rest) != 0 {
return nil, errors.New("x509: trailing data after RSA public key")
}
if p.N.Sign() <= 0 {
return nil, errors.New("x509: RSA modulus is not a positive number")
}
if p.E <= 0 {
return nil, errors.New("x509: RSA public exponent is not a positive number")
}
pub := &rsa.PublicKey{
E: p.E,
N: p.N,
}
return pub, nil
case DSA:
var p *big.Int
rest, err := asn1.Unmarshal(asn1Data, &p)
if err != nil {
return nil, err
}
if len(rest) != 0 {
return nil, errors.New("x509: trailing data after DSA public key")
}
paramsData := keyData.Algorithm.Parameters.FullBytes
params := new(dsaAlgorithmParameters)
rest, err = asn1.Unmarshal(paramsData, params)
if err != nil {
return nil, err
}
if len(rest) != 0 {
return nil, errors.New("x509: trailing data after DSA parameters")
}
if p.Sign() <= 0 || params.P.Sign() <= 0 || params.Q.Sign() <= 0 || params.G.Sign() <= 0 {
return nil, errors.New("x509: zero or negative DSA parameter")
}
pub := &dsa.PublicKey{
Parameters: dsa.Parameters{
P: params.P,
Q: params.Q,
G: params.G,
},
Y: p,
}
return pub, nil
case ECDSA:
paramsData := keyData.Algorithm.Parameters.FullBytes
namedCurveOID := new(asn1.ObjectIdentifier)
rest, err := asn1.Unmarshal(paramsData, namedCurveOID)
if err != nil {
return nil, err
}
if len(rest) != 0 {
return nil, errors.New("x509: trailing data after ECDSA parameters")
}
namedCurve := namedCurveFromOID(*namedCurveOID)
if namedCurve == nil {
return nil, errors.New("x509: unsupported elliptic curve")
}
x, y := elliptic.Unmarshal(namedCurve, asn1Data)
if x == nil {
return nil, errors.New("x509: failed to unmarshal elliptic curve point")
}
pub := &ecdsa.PublicKey{
Curve: namedCurve,
X: x,
Y: y,
}
return pub, nil
default:
return nil, nil
}
}
func parseSANExtension(value []byte) (dnsNames, emailAddresses []string, ipAddresses []net.IP, err error) {
// RFC 5280, 4.2.1.6
// SubjectAltName ::= GeneralNames
//
// GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName
//
// GeneralName ::= CHOICE {
// otherName [0] OtherName,
// rfc822Name [1] IA5String,
// dNSName [2] IA5String,
// x400Address [3] ORAddress,
// directoryName [4] Name,
// ediPartyName [5] EDIPartyName,
// uniformResourceIdentifier [6] IA5String,
// iPAddress [7] OCTET STRING,
// registeredID [8] OBJECT IDENTIFIER }
var seq asn1.RawValue
var rest []byte
if rest, err = asn1.Unmarshal(value, &seq); err != nil {
return
} else if len(rest) != 0 {
err = errors.New("x509: trailing data after X.509 extension")
return
}
if !seq.IsCompound || seq.Tag != 16 || seq.Class != 0 {
err = asn1.StructuralError{Msg: "bad SAN sequence"}
return
}
rest = seq.Bytes
for len(rest) > 0 {
var v asn1.RawValue
rest, err = asn1.Unmarshal(rest, &v)
if err != nil {
return
}
switch v.Tag {
case 1:
emailAddresses = append(emailAddresses, string(v.Bytes))
case 2:
dnsNames = append(dnsNames, string(v.Bytes))
case 7:
switch len(v.Bytes) {
case net.IPv4len, net.IPv6len:
ipAddresses = append(ipAddresses, v.Bytes)
default:
err = errors.New("x509: certificate contained IP address of length " + strconv.Itoa(len(v.Bytes)))
return
}
}
}
return
}
func parseCertificate(in *certificate) (*Certificate, error) {
out := new(Certificate)
out.Raw = in.Raw
out.RawTBSCertificate = in.TBSCertificate.Raw
out.RawSubjectPublicKeyInfo = in.TBSCertificate.PublicKey.Raw
out.RawSubject = in.TBSCertificate.Subject.FullBytes
out.RawIssuer = in.TBSCertificate.Issuer.FullBytes
out.Signature = in.SignatureValue.RightAlign()
out.SignatureAlgorithm =
getSignatureAlgorithmFromOID(in.TBSCertificate.SignatureAlgorithm.Algorithm)
out.PublicKeyAlgorithm =
getPublicKeyAlgorithmFromOID(in.TBSCertificate.PublicKey.Algorithm.Algorithm)
var err error
out.PublicKey, err = parsePublicKey(out.PublicKeyAlgorithm, &in.TBSCertificate.PublicKey)
if err != nil {
return nil, err
}
out.Version = in.TBSCertificate.Version + 1
out.SerialNumber = in.TBSCertificate.SerialNumber
var issuer, subject pkix.RDNSequence
if rest, err := asn1.Unmarshal(in.TBSCertificate.Subject.FullBytes, &subject); err != nil {
return nil, err
} else if len(rest) != 0 {
return nil, errors.New("x509: trailing data after X.509 subject")
}
if rest, err := asn1.Unmarshal(in.TBSCertificate.Issuer.FullBytes, &issuer); err != nil {
return nil, err
} else if len(rest) != 0 {
return nil, errors.New("x509: trailing data after X.509 subject")
}
out.Issuer.FillFromRDNSequence(&issuer)
out.Subject.FillFromRDNSequence(&subject)
out.NotBefore = in.TBSCertificate.Validity.NotBefore
out.NotAfter = in.TBSCertificate.Validity.NotAfter
for _, e := range in.TBSCertificate.Extensions {
out.Extensions = append(out.Extensions, e)
unhandled := false
if len(e.Id) == 4 && e.Id[0] == 2 && e.Id[1] == 5 && e.Id[2] == 29 {
switch e.Id[3] {
case 15:
// RFC 5280, 4.2.1.3
var usageBits asn1.BitString
if rest, err := asn1.Unmarshal(e.Value, &usageBits); err != nil {
return nil, err
} else if len(rest) != 0 {
return nil, errors.New("x509: trailing data after X.509 KeyUsage")
}
var usage int
for i := 0; i < 9; i++ {
if usageBits.At(i) != 0 {
usage |= 1 << uint(i)
}
}
out.KeyUsage = KeyUsage(usage)
case 19:
// RFC 5280, 4.2.1.9
var constraints basicConstraints
if rest, err := asn1.Unmarshal(e.Value, &constraints); err != nil {
return nil, err
} else if len(rest) != 0 {
return nil, errors.New("x509: trailing data after X.509 BasicConstraints")