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,
})
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
}
// CreateSignature builds a signature over the given data using the specified hash algorithm and private key.
func CreateSignature(privKey crypto.PrivateKey, hashAlgo HashAlgorithm, data []byte) (DigitallySigned, error) {
var sig DigitallySigned
sig.Algorithm.Hash = hashAlgo
hash, hashType, err := generateHash(sig.Algorithm.Hash, data)
if err != nil {
return sig, err
}
switch privKey := privKey.(type) {
case rsa.PrivateKey:
sig.Algorithm.Signature = RSA
sig.Signature, err = rsa.SignPKCS1v15(rand.Reader, &privKey, hashType, hash)
return sig, err
case ecdsa.PrivateKey:
sig.Algorithm.Signature = ECDSA
var ecdsaSig dsaSig
ecdsaSig.R, ecdsaSig.S, err = ecdsa.Sign(rand.Reader, &privKey, hash)
if err != nil {
return sig, err
}
sig.Signature, err = asn1.Marshal(ecdsaSig)
return sig, err
default:
return sig, fmt.Errorf("unsupported private key type %T", privKey)
}
}
// 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
}
func subjectBytes(cert *Certificate) ([]byte, error) {
if len(cert.RawSubject) > 0 {
return cert.RawSubject, nil
}
return asn1.Marshal(cert.Subject.ToRDNSequence())
}
// MarshalECPrivateKey marshals an EC private key into ASN.1, DER format.
func MarshalECPrivateKey(key *ecdsa.PrivateKey) ([]byte, error) {
oid, ok := oidFromNamedCurve(key.Curve)
if !ok {
return nil, errors.New("x509: unknown elliptic curve")
}
return asn1.Marshal(ecPrivateKey{
Version: 1,
PrivateKey: key.D.Bytes(),
NamedCurveOID: oid,
PublicKey: asn1.BitString{Bytes: elliptic.Marshal(key.Curve, key.X, key.Y)},
})
}
// 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.UTC(),
NextUpdate: expiry.UTC(),
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},
})
}
// MarshalECPrivateKey marshals an EC private key into ASN.1, DER format.
func MarshalECPrivateKey(key *ecdsa.PrivateKey) ([]byte, error) {
oid, ok := oidFromNamedCurve(key.Curve)
if !ok {
return nil, errors.New("x509: unknown elliptic curve")
}
privateKeyBytes := key.D.Bytes()
paddedPrivateKey := make([]byte, (key.Curve.Params().N.BitLen()+7)/8)
copy(paddedPrivateKey[len(paddedPrivateKey)-len(privateKeyBytes):], privateKeyBytes)
return asn1.Marshal(ecPrivateKey{
Version: 1,
PrivateKey: paddedPrivateKey,
NamedCurveOID: oid,
PublicKey: asn1.BitString{Bytes: elliptic.Marshal(key.Curve, key.X, key.Y)},
})
}
// 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
}
// CreateCertificate creates a new certificate based on a template. The
// following members of template are used: SerialNumber, Subject, NotBefore,
// NotAfter, KeyUsage, ExtKeyUsage, UnknownExtKeyUsage, 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 types are RSA and ECDSA (*rsa.PublicKey or
// *ecdsa.PublicKey for pub, *rsa.PrivateKey or *ecdsa.PublicKey for priv).
func CreateCertificate(rand io.Reader, template, parent *Certificate, pub interface{}, priv interface{}) (cert []byte, err error) {
var publicKeyBytes []byte
var publicKeyAlgorithm pkix.AlgorithmIdentifier
if publicKeyBytes, publicKeyAlgorithm, err = marshalPublicKey(pub); err != nil {
return nil, err
}
var signatureAlgorithm pkix.AlgorithmIdentifier
var hashFunc crypto.Hash
switch priv := priv.(type) {
case *rsa.PrivateKey:
signatureAlgorithm.Algorithm = oidSignatureSHA1WithRSA
hashFunc = crypto.SHA1
case *ecdsa.PrivateKey:
switch priv.Curve {
case elliptic.P256():
hashFunc = crypto.SHA256
signatureAlgorithm.Algorithm = oidSignatureECDSAWithSHA256
case elliptic.P384():
hashFunc = crypto.SHA384
signatureAlgorithm.Algorithm = oidSignatureECDSAWithSHA384
case elliptic.P521():
hashFunc = crypto.SHA512
signatureAlgorithm.Algorithm = oidSignatureECDSAWithSHA512
default:
return nil, errors.New("x509: unknown elliptic curve")
}
default:
return nil, errors.New("x509: only RSA and ECDSA private keys supported")
}
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(publicKeyBytes) * 8, Bytes: publicKeyBytes}
c := tbsCertificate{
Version: 2,
SerialNumber: template.SerialNumber,
SignatureAlgorithm: signatureAlgorithm,
Issuer: asn1.RawValue{FullBytes: asn1Issuer},
Validity: validity{template.NotBefore.UTC(), template.NotAfter.UTC()},
Subject: asn1.RawValue{FullBytes: asn1Subject},
PublicKey: publicKeyInfo{nil, publicKeyAlgorithm, encodedPublicKey},
Extensions: extensions,
}
tbsCertContents, err := asn1.Marshal(c)
if err != nil {
return
}
c.Raw = tbsCertContents
h := hashFunc.New()
h.Write(tbsCertContents)
digest := h.Sum(nil)
var signature []byte
switch priv := priv.(type) {
case *rsa.PrivateKey:
signature, err = rsa.SignPKCS1v15(rand, priv, hashFunc, digest)
case *ecdsa.PrivateKey:
var r, s *big.Int
if r, s, err = ecdsa.Sign(rand, priv, digest); err == nil {
signature, err = asn1.Marshal(ecdsaSignature{r, s})
}
default:
panic("internal error")
}
if err != nil {
return
}
cert, err = asn1.Marshal(certificate{
nil,
c,
signatureAlgorithm,
asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
})
return
}
func buildExtensions(template *Certificate) (ret []pkix.Extension, err error) {
ret = make([]pkix.Extension, 10 /* maximum number of elements. */)
n := 0
if template.KeyUsage != 0 &&
!oidInExtensions(oidExtensionKeyUsage, template.ExtraExtensions) {
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 (len(template.ExtKeyUsage) > 0 || len(template.UnknownExtKeyUsage) > 0) &&
!oidInExtensions(oidExtensionExtendedKeyUsage, template.ExtraExtensions) {
ret[n].Id = oidExtensionExtendedKeyUsage
var oids []asn1.ObjectIdentifier
for _, u := range template.ExtKeyUsage {
if oid, ok := oidFromExtKeyUsage(u); ok {
oids = append(oids, oid)
} else {
panic("internal error")
}
}
oids = append(oids, template.UnknownExtKeyUsage...)
ret[n].Value, err = asn1.Marshal(oids)
if err != nil {
return
}
n++
}
if template.BasicConstraintsValid && !oidInExtensions(oidExtensionBasicConstraints, template.ExtraExtensions) {
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 && !oidInExtensions(oidExtensionSubjectKeyId, template.ExtraExtensions) {
ret[n].Id = oidExtensionSubjectKeyId
ret[n].Value, err = asn1.Marshal(template.SubjectKeyId)
if err != nil {
return
}
n++
}
if len(template.AuthorityKeyId) > 0 && !oidInExtensions(oidExtensionAuthorityKeyId, template.ExtraExtensions) {
ret[n].Id = oidExtensionAuthorityKeyId
ret[n].Value, err = asn1.Marshal(authKeyId{template.AuthorityKeyId})
if err != nil {
return
}
n++
}
if (len(template.OCSPServer) > 0 || len(template.IssuingCertificateURL) > 0) &&
!oidInExtensions(oidExtensionAuthorityInfoAccess, template.ExtraExtensions) {
ret[n].Id = oidExtensionAuthorityInfoAccess
var aiaValues []authorityInfoAccess
for _, name := range template.OCSPServer {
aiaValues = append(aiaValues, authorityInfoAccess{
Method: oidAuthorityInfoAccessOcsp,
Location: asn1.RawValue{Tag: 6, Class: 2, Bytes: []byte(name)},
})
}
for _, name := range template.IssuingCertificateURL {
aiaValues = append(aiaValues, authorityInfoAccess{
Method: oidAuthorityInfoAccessIssuers,
Location: asn1.RawValue{Tag: 6, Class: 2, Bytes: []byte(name)},
})
}
ret[n].Value, err = asn1.Marshal(aiaValues)
if err != nil {
return
}
n++
}
if (len(template.DNSNames) > 0 || len(template.EmailAddresses) > 0 || len(template.IPAddresses) > 0) &&
!oidInExtensions(oidExtensionSubjectAltName, template.ExtraExtensions) {
ret[n].Id = oidExtensionSubjectAltName
var rawValues []asn1.RawValue
for _, name := range template.DNSNames {
rawValues = append(rawValues, asn1.RawValue{Tag: 2, Class: 2, Bytes: []byte(name)})
}
for _, email := range template.EmailAddresses {
rawValues = append(rawValues, asn1.RawValue{Tag: 1, Class: 2, Bytes: []byte(email)})
}
for _, rawIP := range template.IPAddresses {
// If possible, we always want to encode IPv4 addresses in 4 bytes.
ip := rawIP.To4()
if ip == nil {
ip = rawIP
}
rawValues = append(rawValues, asn1.RawValue{Tag: 7, Class: 2, Bytes: ip})
}
ret[n].Value, err = asn1.Marshal(rawValues)
if err != nil {
return
}
n++
}
if len(template.PolicyIdentifiers) > 0 &&
!oidInExtensions(oidExtensionCertificatePolicies, template.ExtraExtensions) {
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 &&
!oidInExtensions(oidExtensionNameConstraints, template.ExtraExtensions) {
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.CRLDistributionPoints) > 0 &&
!oidInExtensions(oidExtensionCRLDistributionPoints, template.ExtraExtensions) {
ret[n].Id = oidExtensionCRLDistributionPoints
var crlDp []distributionPoint
for _, name := range template.CRLDistributionPoints {
rawFullName, _ := asn1.Marshal(asn1.RawValue{Tag: 6, Class: 2, Bytes: []byte(name)})
dp := distributionPoint{
DistributionPoint: distributionPointName{
FullName: asn1.RawValue{Tag: 0, Class: 2, Bytes: rawFullName},
},
}
crlDp = append(crlDp, dp)
}
ret[n].Value, err = asn1.Marshal(crlDp)
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 append(ret[:n], template.ExtraExtensions...), nil
}