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@agl agl/gen.go
Created Apr 15, 2012

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GPG/X.509 certificates
package main
import (
"bytes"
"code.google.com/p/go.crypto/openpgp"
"crypto/rand"
"crypto/rsa"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"github.com/agl/gpgx509/x509"
"math/big"
"os"
"time"
)
// This example code reads a GPG key in "gpg-private-key", generates an RSA
// key, signs the RSA key with the GPG key and then creates a self-signed
// certificate with the GPG signature embedded.
//
// The GPG signature is embedded with a OID stolen from the PKIX arc, which
// should be replaced with something real before actual use.
//
// You can export the private key with:
// gpg --export-secret-keys "My Identity" > gpg-private-key
func main() {
gpgKey, err := os.Open("gpg-private-key")
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to open GPG private key: %s\n", err)
return
}
el, err := openpgp.ReadKeyRing(gpgKey)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to parse GPG private key (note: it shouldn't be armored): %s\n", err)
return
}
if len(el) != 1 {
fmt.Fprintf(os.Stderr, "Found %d entities in the private key file, only wanted one\n", len(el))
return
}
rsaPriv, _ := rsa.GenerateKey(rand.Reader, 1024)
rsaBytes, err := x509.MarshalPKIXPublicKey(&rsaPriv.PublicKey)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to serialise public key: %s\n", err)
return
}
pem.Encode(os.Stdout, &pem.Block{Bytes: rsaBytes, Type: "PUBLIC KEY"})
var message bytes.Buffer
message.Write([]byte("GPG/X.509 key signature:"))
message.Write(rsaBytes)
entity := el[0]
var sigBuf bytes.Buffer
if err := openpgp.DetachSign(&sigBuf, entity, &message, nil); err != nil {
fmt.Fprintf(os.Stderr, "Failed to sign key: %s\n", err)
return
}
maxSerial := new(big.Int).SetInt64(1)
maxSerial.Lsh(maxSerial, 128)
serial, _ := rand.Int(rand.Reader, maxSerial)
now := time.Now()
// This picks a *random* identity from the key
var identity string
for k := range entity.Identities {
identity = k
}
template := x509.Certificate{
SerialNumber: serial,
Subject: pkix.Name{
CommonName: "GPG/X.509",
},
NotBefore: now.Add(-5 * time.Minute).UTC(),
NotAfter: now.AddDate(1, 0, 0).UTC(), // valid for 1 year.
KeyUsage: x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageClientAuth},
GPGIdentity: identity,
GPGSignature: sigBuf.Bytes(),
}
derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &rsaPriv.PublicKey, rsaPriv)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to create certificate: %s\n", err)
return
}
pem.Encode(os.Stdout, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
}
// Copyright 2011 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
import (
"crypto/rsa"
"encoding/asn1"
"errors"
"math/big"
)
// pkcs1PrivateKey is a structure which mirrors the PKCS#1 ASN.1 for an RSA private key.
type pkcs1PrivateKey struct {
Version int
N *big.Int
E int
D *big.Int
P *big.Int
Q *big.Int
// We ignore these values, if present, because rsa will calculate them.
Dp *big.Int `asn1:"optional"`
Dq *big.Int `asn1:"optional"`
Qinv *big.Int `asn1:"optional"`
AdditionalPrimes []pkcs1AdditionalRSAPrime `asn1:"optional,omitempty"`
}
type pkcs1AdditionalRSAPrime struct {
Prime *big.Int
// We ignore these values because rsa will calculate them.
Exp *big.Int
Coeff *big.Int
}
// ParsePKCS1PrivateKey returns an RSA private key from its ASN.1 PKCS#1 DER encoded form.
func ParsePKCS1PrivateKey(der []byte) (key *rsa.PrivateKey, err error) {
var priv pkcs1PrivateKey
rest, err := asn1.Unmarshal(der, &priv)
if len(rest) > 0 {
err = asn1.SyntaxError{Msg: "trailing data"}
return
}
if err != nil {
return
}
if priv.Version > 1 {
return nil, errors.New("x509: unsupported private key version")
}
if priv.N.Sign() <= 0 || priv.D.Sign() <= 0 || priv.P.Sign() <= 0 || priv.Q.Sign() <= 0 {
return nil, errors.New("private key contains zero or negative value")
}
key = new(rsa.PrivateKey)
key.PublicKey = rsa.PublicKey{
E: priv.E,
N: priv.N,
}
key.D = priv.D
key.Primes = make([]*big.Int, 2+len(priv.AdditionalPrimes))
key.Primes[0] = priv.P
key.Primes[1] = priv.Q
for i, a := range priv.AdditionalPrimes {
if a.Prime.Sign() <= 0 {
return nil, errors.New("private key contains zero or negative prime")
}
key.Primes[i+2] = a.Prime
// We ignore the other two values because rsa will calculate
// them as needed.
}
err = key.Validate()
if err != nil {
return nil, err
}
key.Precompute()
return
}
// MarshalPKCS1PrivateKey converts a private key to ASN.1 DER encoded form.
func MarshalPKCS1PrivateKey(key *rsa.PrivateKey) []byte {
key.Precompute()
version := 0
if len(key.Primes) > 2 {
version = 1
}
priv := pkcs1PrivateKey{
Version: version,
N: key.N,
E: key.PublicKey.E,
D: key.D,
P: key.Primes[0],
Q: key.Primes[1],
Dp: key.Precomputed.Dp,
Dq: key.Precomputed.Dq,
Qinv: key.Precomputed.Qinv,
}
priv.AdditionalPrimes = make([]pkcs1AdditionalRSAPrime, len(key.Precomputed.CRTValues))
for i, values := range key.Precomputed.CRTValues {
priv.AdditionalPrimes[i].Prime = key.Primes[2+i]
priv.AdditionalPrimes[i].Exp = values.Exp
priv.AdditionalPrimes[i].Coeff = values.Coeff
}
b, _ := asn1.Marshal(priv)
return b
}
// rsaPublicKey reflects the ASN.1 structure of a PKCS#1 public key.
type rsaPublicKey struct {
N *big.Int
E int
}
// 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/rsa"
"crypto/sha1"
"crypto/x509/pkix"
"encoding/asn1"
"encoding/pem"
"errors"
"io"
"math/big"
"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".
func ParsePKIXPublicKey(derBytes []byte) (pub interface{}, err error) {
var pki publicKeyInfo
if _, err = asn1.Unmarshal(derBytes, &pki); err != nil {
return
}
algo := getPublicKeyAlgorithmFromOID(pki.Algorithm.Algorithm)
if algo == UnknownPublicKeyAlgorithm {
return nil, errors.New("ParsePKIXPublicKey: unknown public key algorithm")
}
return parsePublicKey(algo, &pki)
}
// MarshalPKIXPublicKey serialises a public key to DER-encoded PKIX format.
func MarshalPKIXPublicKey(pub interface{}) ([]byte, error) {
var pubBytes []byte
switch pub := pub.(type) {
case *rsa.PublicKey:
pubBytes, _ = asn1.Marshal(rsaPublicKey{
N: pub.N,
E: pub.E,
})
default:
return nil, errors.New("MarshalPKIXPublicKey: unknown public key type")
}
pkix := pkixPublicKey{
Algo: pkix.AlgorithmIdentifier{
Algorithm: []int{1, 2, 840, 113549, 1, 1, 1},
// 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.
Parameters: asn1.RawValue{
Tag: 5,
},
},
BitString: asn1.BitString{
Bytes: pubBytes,
BitLength: 8 * len(pubBytes),
},
}
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:1,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 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
)
type PublicKeyAlgorithm int
const (
UnknownPublicKeyAlgorithm PublicKeyAlgorithm = iota
RSA
DSA
)
// 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 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}
//
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, 4, 3, 2}
)
func getSignatureAlgorithmFromOID(oid asn1.ObjectIdentifier) SignatureAlgorithm {
switch {
case oid.Equal(oidSignatureMD2WithRSA):
return MD2WithRSA
case oid.Equal(oidSignatureMD5WithRSA):
return MD5WithRSA
case oid.Equal(oidSignatureSHA1WithRSA):
return SHA1WithRSA
case oid.Equal(oidSignatureSHA256WithRSA):
return SHA256WithRSA
case oid.Equal(oidSignatureSHA384WithRSA):
return SHA384WithRSA
case oid.Equal(oidSignatureSHA512WithRSA):
return SHA512WithRSA
case oid.Equal(oidSignatureDSAWithSHA1):
return DSAWithSHA1
case oid.Equal(oidSignatureDSAWithSHA256):
return DSAWithSHA256
}
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 }
var (
oidPublicKeyRsa = asn1.ObjectIdentifier{1, 2, 840, 113549, 1, 1, 1}
oidPublicKeyDsa = asn1.ObjectIdentifier{1, 2, 840, 10040, 4, 1}
)
func getPublicKeyAlgorithmFromOID(oid asn1.ObjectIdentifier) PublicKeyAlgorithm {
switch {
case oid.Equal(oidPublicKeyRsa):
return RSA
case oid.Equal(oidPublicKeyDsa):
return DSA
}
return UnknownPublicKeyAlgorithm
}
// 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}
oidExtKeyUsageTimeStamping = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 8}
oidExtKeyUsageOCSPSigning = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 9}
)
// 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
ExtKeyUsageTimeStamping
ExtKeyUsageOCSPSigning
)
// 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
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
GPGIdentity string
GPGSignature []byte
SubjectKeyId []byte
AuthorityKeyId []byte
// Subject Alternate Name values
DNSNames []string
EmailAddresses []string
// Name constraints
PermittedDNSDomainsCritical bool // if true then the name constraints are marked critical.
PermittedDNSDomains []string
PolicyIdentifiers []asn1.ObjectIdentifier
}
// ErrUnsupportedAlgorithm results from attempting to perform an operation that
// involves algorithms that are not currently implemented.
var ErrUnsupportedAlgorithm = errors.New("crypto/x509: cannot verify signature: algorithm unimplemented")
// 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 "crypto/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)
}
// CheckSignatureFrom verifies that the signature on c is a valid signature
// from parent.
func (c *Certificate) CheckSignatureFrom(parent *Certificate) (err 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
}
// 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) (err error) {
var hashType crypto.Hash
switch algo {
case SHA1WithRSA, DSAWithSHA1:
hashType = crypto.SHA1
case SHA256WithRSA, DSAWithSHA256:
hashType = crypto.SHA256
case SHA384WithRSA:
hashType = crypto.SHA384
case SHA512WithRSA:
hashType = crypto.SHA512
default:
return ErrUnsupportedAlgorithm
}
h := hashType.New()
if h == nil {
return ErrUnsupportedAlgorithm
}
h.Write(signed)
digest := h.Sum(nil)
switch pub := c.PublicKey.(type) {
case *rsa.PublicKey:
return rsa.VerifyPKCS1v15(pub, hashType, digest, signature)
case *dsa.PublicKey:
dsaSig := new(dsaSignature)
if _, err := asn1.Unmarshal(signature, dsaSig); err != nil {
return err
}
if dsaSig.R.Sign() <= 0 || dsaSig.S.Sign() <= 0 {
return errors.New("DSA signature contained zero or negative values")
}
if !dsa.Verify(pub, digest, dsaSig.R, dsaSig.S) {
return errors.New("DSA verification failure")
}
return
}
return ErrUnsupportedAlgorithm
}
// CheckCRLSignature checks that the signature in crl is from c.
func (c *Certificate) CheckCRLSignature(crl *pkix.CertificateList) (err 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 "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"`
Min int `asn1:"optional,tag:0"`
Max int `asn1:"optional,tag:1"`
}
func parsePublicKey(algo PublicKeyAlgorithm, keyData *publicKeyInfo) (interface{}, error) {
asn1Data := keyData.PublicKey.RightAlign()
switch algo {
case RSA:
p := new(rsaPublicKey)
_, err := asn1.Unmarshal(asn1Data, p)
if err != nil {
return nil, err
}
pub := &rsa.PublicKey{
E: p.E,
N: p.N,
}
return pub, nil
case DSA:
var p *big.Int
_, err := asn1.Unmarshal(asn1Data, &p)
if err != nil {
return nil, err
}
paramsData := keyData.Algorithm.Parameters.FullBytes
params := new(dsaAlgorithmParameters)
_, err = asn1.Unmarshal(paramsData, params)
if err != nil {
return nil, err
}
if p.Sign() <= 0 || params.P.Sign() <= 0 || params.Q.Sign() <= 0 || params.G.Sign() <= 0 {
return nil, errors.New("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
default:
return nil, nil
}
panic("unreachable")
}
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
}
if in.TBSCertificate.SerialNumber.Sign() < 0 {
return nil, errors.New("negative serial number")
}
out.Version = in.TBSCertificate.Version + 1
out.SerialNumber = in.TBSCertificate.SerialNumber
var issuer, subject pkix.RDNSequence
if _, err := asn1.Unmarshal(in.TBSCertificate.Subject.FullBytes, &subject); err != nil {
return nil, err
}
if _, err := asn1.Unmarshal(in.TBSCertificate.Issuer.FullBytes, &issuer); err != nil {
return nil, err
}
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 {
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
_, err := asn1.Unmarshal(e.Value, &usageBits)
if err == nil {
var usage int
for i := 0; i < 9; i++ {
if usageBits.At(i) != 0 {
usage |= 1 << uint(i)
}
}
out.KeyUsage = KeyUsage(usage)
continue
}
case 19:
// RFC 5280, 4.2.1.9
var constraints basicConstraints
_, err := asn1.Unmarshal(e.Value, &constraints)
if err == nil {
out.BasicConstraintsValid = true
out.IsCA = constraints.IsCA
out.MaxPathLen = constraints.MaxPathLen
continue
}
case 17:
// 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
_, err := asn1.Unmarshal(e.Value, &seq)
if err != nil {
return nil, err
}
if !seq.IsCompound || seq.Tag != 16 || seq.Class != 0 {
return nil, asn1.StructuralError{Msg: "bad SAN sequence"}
}
parsedName := false
rest := seq.Bytes
for len(rest) > 0 {
var v asn1.RawValue
rest, err = asn1.Unmarshal(rest, &v)
if err != nil {
return nil, err
}
switch v.Tag {
case 1:
out.EmailAddresses = append(out.EmailAddresses, string(v.Bytes))
parsedName = true
case 2:
out.DNSNames = append(out.DNSNames, string(v.Bytes))
parsedName = true
}
}
if parsedName {
continue
}
// If we didn't parse any of the names then we
// fall through to the critical check below.
case 30:
// RFC 5280, 4.2.1.10
// NameConstraints ::= SEQUENCE {
// permittedSubtrees [0] GeneralSubtrees OPTIONAL,
// excludedSubtrees [1] GeneralSubtrees OPTIONAL }
//
// GeneralSubtrees ::= SEQUENCE SIZE (1..MAX) OF GeneralSubtree
//
// GeneralSubtree ::= SEQUENCE {
// base GeneralName,
// minimum [0] BaseDistance DEFAULT 0,
// maximum [1] BaseDistance OPTIONAL }
//
// BaseDistance ::= INTEGER (0..MAX)
var constraints nameConstraints
_, err := asn1.Unmarshal(e.Value, &constraints)
if err != nil {
return nil, err
}
if len(constraints.Excluded) > 0 && e.Critical {
return out, UnhandledCriticalExtension{}
}
for _, subtree := range constraints.Permitted {
if subtree.Min > 0 || subtree.Max > 0 || len(subtree.Name) == 0 {
if e.Critical {
return out, UnhandledCriticalExtension{}
}
continue
}
out.PermittedDNSDomains = append(out.PermittedDNSDomains, subtree.Name)
}
continue
case 35:
// RFC 5280, 4.2.1.1
var a authKeyId
_, err = asn1.Unmarshal(e.Value, &a)
if err != nil {
return nil, err
}
out.AuthorityKeyId = a.Id
continue
case 37:
// RFC 5280, 4.2.1.12. Extended Key Usage
// id-ce-extKeyUsage OBJECT IDENTIFIER ::= { id-ce 37 }
//
// ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId
//
// KeyPurposeId ::= OBJECT IDENTIFIER
var keyUsage []asn1.ObjectIdentifier
_, err = asn1.Unmarshal(e.Value, &keyUsage)
if err != nil {
return nil, err
}
for _, u := range keyUsage {
switch {
case u.Equal(oidExtKeyUsageAny):
out.ExtKeyUsage = append(out.ExtKeyUsage, ExtKeyUsageAny)
case u.Equal(oidExtKeyUsageServerAuth):
out.ExtKeyUsage = append(out.ExtKeyUsage, ExtKeyUsageServerAuth)
case u.Equal(oidExtKeyUsageClientAuth):
out.ExtKeyUsage = append(out.ExtKeyUsage, ExtKeyUsageClientAuth)
case u.Equal(oidExtKeyUsageCodeSigning):
out.ExtKeyUsage = append(out.ExtKeyUsage, ExtKeyUsageCodeSigning)
case u.Equal(oidExtKeyUsageEmailProtection):
out.ExtKeyUsage = append(out.ExtKeyUsage, ExtKeyUsageEmailProtection)
case u.Equal(oidExtKeyUsageTimeStamping):
out.ExtKeyUsage = append(out.ExtKeyUsage, ExtKeyUsageTimeStamping)
case u.Equal(oidExtKeyUsageOCSPSigning):
out.ExtKeyUsage = append(out.ExtKeyUsage, ExtKeyUsageOCSPSigning)
default:
out.UnknownExtKeyUsage = append(out.UnknownExtKeyUsage, u)
}
}
continue
case 14:
// RFC 5280, 4.2.1.2
var keyid []byte
_, err = asn1.Unmarshal(e.Value, &keyid)
if err != nil {
return nil, err
}
out.SubjectKeyId = keyid
continue
case 32:
// RFC 5280 4.2.1.4: Certificate Policies
var policies []policyInformation
if _, err = asn1.Unmarshal(e.Value, &policies); err != nil {
return nil, err
}
out.PolicyIdentifiers = make([]asn1.ObjectIdentifier, len(policies))
for i, policy := range policies {
out.PolicyIdentifiers[i] = policy.Policy
}
}
}
if e.Critical {
return out, UnhandledCriticalExtension{}
}
}
return out, nil
}
// ParseCertificate parses a single certificate from the given ASN.1 DER data.
func ParseCertificate(asn1Data []byte) (*Certificate, error) {
var cert certificate
rest, err := asn1.Unmarshal(asn1Data, &cert)
if err != nil {
return nil, err
}
if len(rest) > 0 {
return nil, asn1.SyntaxError{Msg: "trailing data"}
}
return parseCertificate(&cert)
}
// ParseCertificates parses one or more certificates from the given ASN.1 DER
// data. The certificates must be concatenated with no intermediate padding.
func ParseCertificates(asn1Data []byte) ([]*Certificate, error) {
var v []*certificate
for len(asn1Data) > 0 {
cert := new(certificate)
var err error
asn1Data, err = asn1.Unmarshal(asn1Data, cert)
if err != nil {
return nil, err
}
v = append(v, cert)
}
ret := make([]*Certificate, len(v))
for i, ci := range v {
cert, err := parseCertificate(ci)
if err != nil {
return nil, err
}
ret[i] = cert
}
return ret, nil
}
func reverseBitsInAByte(in byte) byte {
b1 := in>>4 | in<<4
b2 := b1>>2&0x33 | b1<<2&0xcc
b3 := b2>>1&0x55 | b2<<1&0xaa
return b3
}
var (
oidExtensionSubjectKeyId = []int{2, 5, 29, 14}
oidExtensionKeyUsage = []int{2, 5, 29, 15}
oidExtensionAuthorityKeyId = []int{2, 5, 29, 35}
oidExtensionBasicConstraints = []int{2, 5, 29, 19}
oidExtensionSubjectAltName = []int{2, 5, 29, 17}
oidExtensionCertificatePolicies = []int{2, 5, 29, 32}
oidExtensionNameConstraints = []int{2, 5, 29, 30}
oidGPGSignature = []int{2, 5, 29, 666666}
)
func buildExtensions(template *Certificate) (ret []pkix.Extension, err error) {
ret = make([]pkix.Extension, 8 /* maximum number of elements. */)
n := 0
if template.KeyUsage != 0 {
ret[n].Id = oidExtensionKeyUsage
ret[n].Critical = true
var a [2]byte
a[0] = reverseBitsInAByte(byte(template.KeyUsage))
a[1] = reverseBitsInAByte(byte(template.KeyUsage >> 8))
l := 1
if a[1] != 0 {
l = 2
}
ret[n].Value, err = asn1.Marshal(asn1.BitString{Bytes: a[0:l], BitLength: l * 8})
if err != nil {
return
}
n++
}
if template.BasicConstraintsValid {
ret[n].Id = oidExtensionBasicConstraints
ret[n].Value, err = asn1.Marshal(basicConstraints{template.IsCA, template.MaxPathLen})
ret[n].Critical = true
if err != nil {
return
}
n++
}
if len(template.SubjectKeyId) > 0 {
ret[n].Id = oidExtensionSubjectKeyId
ret[n].Value, err = asn1.Marshal(template.SubjectKeyId)
if err != nil {
return
}
n++
}
if len(template.AuthorityKeyId) > 0 {
ret[n].Id = oidExtensionAuthorityKeyId
ret[n].Value, err = asn1.Marshal(authKeyId{template.AuthorityKeyId})
if err != nil {
return
}
n++
}
if len(template.DNSNames) > 0 {
ret[n].Id = oidExtensionSubjectAltName
rawValues := make([]asn1.RawValue, len(template.DNSNames))
for i, name := range template.DNSNames {
rawValues[i] = asn1.RawValue{Tag: 2, Class: 2, Bytes: []byte(name)}
}
ret[n].Value, err = asn1.Marshal(rawValues)
if err != nil {
return
}
n++
}
if len(template.PolicyIdentifiers) > 0 {
ret[n].Id = oidExtensionCertificatePolicies
policies := make([]policyInformation, len(template.PolicyIdentifiers))
for i, policy := range template.PolicyIdentifiers {
policies[i].Policy = policy
}
ret[n].Value, err = asn1.Marshal(policies)
if err != nil {
return
}
n++
}
if len(template.PermittedDNSDomains) > 0 {
ret[n].Id = oidExtensionNameConstraints
ret[n].Critical = template.PermittedDNSDomainsCritical
var out nameConstraints
out.Permitted = make([]generalSubtree, len(template.PermittedDNSDomains))
for i, permitted := range template.PermittedDNSDomains {
out.Permitted[i] = generalSubtree{Name: permitted}
}
ret[n].Value, err = asn1.Marshal(out)
if err != nil {
return
}
n++
}
if len(template.GPGSignature) > 0 {
ret[n].Id = oidGPGSignature
type gpgBlob struct {
Identity string
Signature []byte
}
ret[n].Value, err = asn1.Marshal(gpgBlob{
Identity: template.GPGIdentity,
Signature: template.GPGSignature,
})
if err != nil {
return
}
n++
}
// Adding another extension here? Remember to update the maximum number
// of elements in the make() at the top of the function.
return ret[0:n], nil
}
var (
oidSHA1WithRSA = []int{1, 2, 840, 113549, 1, 1, 5}
oidRSA = []int{1, 2, 840, 113549, 1, 1, 1}
)
func subjectBytes(cert *Certificate) ([]byte, error) {
if len(cert.RawSubject) > 0 {
return cert.RawSubject, nil
}
return asn1.Marshal(cert.Subject.ToRDNSequence())
}
// CreateCertificate creates a new certificate based on a template. The
// following members of template are used: SerialNumber, Subject, NotBefore,
// NotAfter, KeyUsage, BasicConstraintsValid, IsCA, MaxPathLen, SubjectKeyId,
// DNSNames, PermittedDNSDomainsCritical, PermittedDNSDomains.
//
// The certificate is signed by parent. If parent is equal to template then the
// certificate is self-signed. The parameter pub is the public key of the
// signee and priv is the private key of the signer.
//
// The returned slice is the certificate in DER encoding.
//
// The only supported key type is RSA (*rsa.PublicKey for pub, *rsa.PrivateKey
// for priv).
func CreateCertificate(rand io.Reader, template, parent *Certificate, pub interface{}, priv interface{}) (cert []byte, err error) {
rsaPub, ok := pub.(*rsa.PublicKey)
if !ok {
return nil, errors.New("x509: non-RSA public keys not supported")
}
rsaPriv, ok := priv.(*rsa.PrivateKey)
if !ok {
return nil, errors.New("x509: non-RSA private keys not supported")
}
asn1PublicKey, err := asn1.Marshal(rsaPublicKey{
N: rsaPub.N,
E: rsaPub.E,
})
if err != nil {
return
}
if len(parent.SubjectKeyId) > 0 {
template.AuthorityKeyId = parent.SubjectKeyId
}
extensions, err := buildExtensions(template)
if err != nil {
return
}
asn1Issuer, err := subjectBytes(parent)
if err != nil {
return
}
asn1Subject, err := subjectBytes(template)
if err != nil {
return
}
encodedPublicKey := asn1.BitString{BitLength: len(asn1PublicKey) * 8, Bytes: asn1PublicKey}
c := tbsCertificate{
Version: 2,
SerialNumber: template.SerialNumber,
SignatureAlgorithm: pkix.AlgorithmIdentifier{Algorithm: oidSHA1WithRSA},
Issuer: asn1.RawValue{FullBytes: asn1Issuer},
Validity: validity{template.NotBefore, template.NotAfter},
Subject: asn1.RawValue{FullBytes: asn1Subject},
PublicKey: publicKeyInfo{nil, pkix.AlgorithmIdentifier{Algorithm: oidRSA}, encodedPublicKey},
Extensions: extensions,
}
tbsCertContents, err := asn1.Marshal(c)
if err != nil {
return
}
c.Raw = tbsCertContents
h := sha1.New()
h.Write(tbsCertContents)
digest := h.Sum(nil)
signature, err := rsa.SignPKCS1v15(rand, rsaPriv, crypto.SHA1, digest)
if err != nil {
return
}
cert, err = asn1.Marshal(certificate{
nil,
c,
pkix.AlgorithmIdentifier{Algorithm: oidSHA1WithRSA},
asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
})
return
}
// pemCRLPrefix is the magic string that indicates that we have a PEM encoded
// CRL.
var pemCRLPrefix = []byte("-----BEGIN X509 CRL")
// pemType is the type of a PEM encoded CRL.
var pemType = "X509 CRL"
// ParseCRL parses a CRL from the given bytes. It's often the case that PEM
// encoded CRLs will appear where they should be DER encoded, so this function
// will transparently handle PEM encoding as long as there isn't any leading
// garbage.
func ParseCRL(crlBytes []byte) (certList *pkix.CertificateList, err error) {
if bytes.HasPrefix(crlBytes, pemCRLPrefix) {
block, _ := pem.Decode(crlBytes)
if block != nil && block.Type == pemType {
crlBytes = block.Bytes
}
}
return ParseDERCRL(crlBytes)
}
// ParseDERCRL parses a DER encoded CRL from the given bytes.
func ParseDERCRL(derBytes []byte) (certList *pkix.CertificateList, err error) {
certList = new(pkix.CertificateList)
_, err = asn1.Unmarshal(derBytes, certList)
if err != nil {
certList = nil
}
return
}
// CreateCRL returns a DER encoded CRL, signed by this Certificate, that
// contains the given list of revoked certificates.
//
// The only supported key type is RSA (*rsa.PrivateKey for priv).
func (c *Certificate) CreateCRL(rand io.Reader, priv interface{}, revokedCerts []pkix.RevokedCertificate, now, expiry time.Time) (crlBytes []byte, err error) {
rsaPriv, ok := priv.(*rsa.PrivateKey)
if !ok {
return nil, errors.New("x509: non-RSA private keys not supported")
}
tbsCertList := pkix.TBSCertificateList{
Version: 2,
Signature: pkix.AlgorithmIdentifier{
Algorithm: oidSignatureSHA1WithRSA,
},
Issuer: c.Subject.ToRDNSequence(),
ThisUpdate: now,
NextUpdate: expiry,
RevokedCertificates: revokedCerts,
}
tbsCertListContents, err := asn1.Marshal(tbsCertList)
if err != nil {
return
}
h := sha1.New()
h.Write(tbsCertListContents)
digest := h.Sum(nil)
signature, err := rsa.SignPKCS1v15(rand, rsaPriv, crypto.SHA1, digest)
if err != nil {
return
}
return asn1.Marshal(pkix.CertificateList{
TBSCertList: tbsCertList,
SignatureAlgorithm: pkix.AlgorithmIdentifier{
Algorithm: oidSignatureSHA1WithRSA,
},
SignatureValue: asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
})
}
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