crypto/x509: support DSA public keys in X.509 certs.

R=agl
CC=golang-dev
https://golang.org/cl/4517072

src/pkg/crypto/x509/x509.go

@@ -11,6 +11,7 @@ import (
 	"bytes"
 	"container/vector"
 	"crypto"
+	"crypto/dsa"
 	"crypto/rsa"
 	"crypto/sha1"
 	"crypto/x509/crl"
@@ -168,8 +169,13 @@ type tbsCertificate struct {
 	Extensions         []extension    "optional,explicit,tag:3"
 }
 
+type dsaAlgorithmParameters struct {
+	P, Q, G asn1.RawValue
+}
+
 type algorithmIdentifier struct {
-	Algorithm asn1.ObjectIdentifier
+	Algorithm  asn1.ObjectIdentifier
+	Parameters asn1.RawValue "optional"
 }
 
 type rdnSequence []relativeDistinguishedNameSET
@@ -219,6 +225,7 @@ type PublicKeyAlgorithm int
 const (
 	UnknownPublicKeyAlgorithm PublicKeyAlgorithm = iota
 	RSA
+	DSA
 )
 
 // Name represents an X.509 distinguished name. This only includes the common
@@ -337,15 +344,27 @@ func getSignatureAlgorithmFromOID(oid []int) SignatureAlgorithm {
 	return UnknownSignatureAlgorithm
 }
 
-func getPublicKeyAlgorithmFromOID(oid []int) PublicKeyAlgorithm {
-	if len(oid) == 7 && oid[0] == 1 && oid[1] == 2 && oid[2] == 840 &&
-		oid[3] == 113549 && oid[4] == 1 && oid[5] == 1 {
-		switch oid[6] {
-		case 1:
-			return RSA
-		}
-	}
+// 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
 }
 
@@ -562,7 +581,8 @@ type generalSubtree struct {
 	Max  int    "optional,tag:1"
 }
 
-func parsePublicKey(algo PublicKeyAlgorithm, asn1Data []byte) (interface{}, os.Error) {
+func parsePublicKey(algo PublicKeyAlgorithm, keyData *publicKeyInfo) (interface{}, os.Error) {
+	asn1Data := keyData.PublicKey.RightAlign()
 	switch algo {
 	case RSA:
 		p := new(rsaPublicKey)
@@ -580,10 +600,38 @@ func parsePublicKey(algo PublicKeyAlgorithm, asn1Data []byte) (interface{}, os.E
 			N: new(big.Int).SetBytes(p.N.Bytes),
 		}
 		return pub, nil
+	case DSA:
+		p := new(asn1.RawValue)
+		_, err := asn1.Unmarshal(asn1Data, p)
+		if err != nil {
+			return nil, err
+		}
+		if !rawValueIsInteger(p) {
+			return nil, asn1.StructuralError{"tags don't match"}
+		}
+		paramsData := keyData.Algorithm.Parameters.FullBytes
+		params := new(dsaAlgorithmParameters)
+		_, err = asn1.Unmarshal(paramsData, params)
+		if err != nil {
+			return nil, err
+		}
+		if !rawValueIsInteger(&params.P) ||
+			!rawValueIsInteger(&params.Q) ||
+			!rawValueIsInteger(&params.G) {
+			return nil, asn1.StructuralError{"tags don't match"}
+		}
+		pub := &dsa.PublicKey{
+			Parameters: dsa.Parameters{
+				P: new(big.Int).SetBytes(params.P.Bytes),
+				Q: new(big.Int).SetBytes(params.Q.Bytes),
+				G: new(big.Int).SetBytes(params.G.Bytes),
+			},
+			Y: new(big.Int).SetBytes(p.Bytes),
+		}
+		return pub, nil
 	default:
 		return nil, nil
 	}
-
 	panic("unreachable")
 }
 
@@ -600,7 +648,7 @@ func parseCertificate(in *certificate) (*Certificate, os.Error) {
 	out.PublicKeyAlgorithm =
 		getPublicKeyAlgorithmFromOID(in.TBSCertificate.PublicKey.Algorithm.Algorithm)
 	var err os.Error
-	out.PublicKey, err = parsePublicKey(out.PublicKeyAlgorithm, in.TBSCertificate.PublicKey.PublicKey.RightAlign())
+	out.PublicKey, err = parsePublicKey(out.PublicKeyAlgorithm, &in.TBSCertificate.PublicKey)
 	if err != nil {
 		return nil, err
 	}
@@ -1004,11 +1052,11 @@ func CreateCertificate(rand io.Reader, template, parent *Certificate, pub *rsa.P
 	c := tbsCertificate{
 		Version:            2,
 		SerialNumber:       asn1.RawValue{Bytes: template.SerialNumber, Tag: 2},
-		SignatureAlgorithm: algorithmIdentifier{oidSHA1WithRSA},
+		SignatureAlgorithm: algorithmIdentifier{Algorithm: oidSHA1WithRSA},
 		Issuer:             parent.Subject.toRDNSequence(),
 		Validity:           validity{template.NotBefore, template.NotAfter},
 		Subject:            template.Subject.toRDNSequence(),
-		PublicKey:          publicKeyInfo{nil, algorithmIdentifier{oidRSA}, encodedPublicKey},
+		PublicKey:          publicKeyInfo{nil, algorithmIdentifier{Algorithm: oidRSA}, encodedPublicKey},
 		Extensions:         extensions,
 	}
 
@@ -1031,7 +1079,7 @@ func CreateCertificate(rand io.Reader, template, parent *Certificate, pub *rsa.P
 	cert, err = asn1.Marshal(certificate{
 		nil,
 		c,
-		algorithmIdentifier{oidSHA1WithRSA},
+		algorithmIdentifier{Algorithm: oidSHA1WithRSA},
 		asn1.BitString{Bytes: signature, BitLength: len(signature) * 8},
 	})
 	return

src/pkg/crypto/x509/x509_test.go

@@ -7,6 +7,7 @@ package x509
 import (
 	"asn1"
 	"big"
+	"crypto/dsa"
 	"crypto/rand"
 	"crypto/rsa"
 	"encoding/hex"
@@ -54,6 +55,12 @@ func fromBase10(base10 string) *big.Int {
 	return i
 }
 
+func bigFromHexString(s string) *big.Int {
+	ret := new(big.Int)
+	ret.SetString(s, 16)
+	return ret
+}
+
 var rsaPrivateKey = &rsa.PrivateKey{
 	PublicKey: rsa.PublicKey{
 		N: bigFromString("9353930466774385905609975137998169297361893554149986716853295022578535724979677252958524466350471210367835187480748268864277464700638583474144061408845077"),
@@ -245,3 +252,58 @@ func TestCreateSelfSignedCertificate(t *testing.T) {
 		return
 	}
 }
+
+var dsaCertPem = `-----BEGIN CERTIFICATE-----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+-----END CERTIFICATE-----
+`
+
+func TestParseCertificateWithDsaPublicKey(t *testing.T) {
+	expectedKey := &dsa.PublicKey{
+		Parameters: dsa.Parameters{
+			P: bigFromHexString("00BC84B52743B169158BB85974E3E832AF5EFCFC42B264349095313A4A013EEE069A1B937D92E51ACF297A1C77880DF25C8607D8204B4DC45651305EF4A63B40C7D8C42D91EDA397D8F51CBC9D0A531FE2C6F1E55E9357D205C39D395358968CBEDAC11320C607BE16CB9DB492B6E78163305A34DD99CE43C64927D13A0040EB97"),
+			Q: bigFromHexString("009A67067F66A323F5D4EC7902C73FE5D9E36FA74F"),
+			G: bigFromHexString("009147778295BF5893542BC41BA806898A29E43261DBC85441C37D92E97ED80D323D44825FDDE8374D0FF15877798812682599B216BBCC31B9DCCAD527465FEAFFD7FC2A193612E575E34E7A98AF4D10339FE47390A518CB9975B3160B1D0285D1418D0977C52994F43C29A053E3D685834104C9FAFDC221E38BE9F3989D7A8E42"),
+		},
+		Y: bigFromHexString("59A27C269FCDE45AA2160A5C980C19211A820095091AB9C5DC8309AB7EC1B3A48C2E267C6D35FEE9B71BCBB92F16AC8E559129347FB5C00BEEDD10BA8915C90698755CA965735A32DC7575BED806E1E38F768FFBC24E41123DC73F1C6E9E4D0C9E692128853AFE29DC665FA993DCA9C903B7BF00B6442B9A76A5DADC6186317A"),
+	}
+	pemBlock, _ := pem.Decode([]byte(dsaCertPem))
+	cert, err := ParseCertificate(pemBlock.Bytes)
+	if err != nil {
+		t.Fatal("Failed to parse certificate: %s", err)
+	}
+	if cert.PublicKeyAlgorithm != DSA {
+		t.Errorf("Parsed key algorithm was not DSA")
+	}
+	parsedKey, ok := cert.PublicKey.(*dsa.PublicKey)
+	if !ok {
+		t.Fatal("Parsed key was not a DSA key: %s", err)
+	}
+	if expectedKey.Y.Cmp(parsedKey.Y) != 0 ||
+		expectedKey.P.Cmp(parsedKey.P) != 0 ||
+		expectedKey.Q.Cmp(parsedKey.Q) != 0 ||
+		expectedKey.G.Cmp(parsedKey.G) != 0 {
+		t.Fatal("Parsed key differs from expected key")
+	}
+}