1 files changed, 83 insertions, 0 deletions
diff --git a/src/crypto/x509/sec1.go b/src/crypto/x509/sec1.go
new file mode 100644
index 000000000..7de66754e
--- /dev/null
+++ b/src/crypto/x509/sec1.go
@@ -0,0 +1,83 @@
+// Copyright 2012 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/ecdsa"
+	"crypto/elliptic"
+	"encoding/asn1"
+	"errors"
+	"fmt"
+	"math/big"
+)
+
+const ecPrivKeyVersion = 1
+
+// ecPrivateKey reflects an ASN.1 Elliptic Curve Private Key Structure.
+// References:
+//   RFC5915
+//   SEC1 - http://www.secg.org/download/aid-780/sec1-v2.pdf
+// Per RFC5915 the NamedCurveOID is marked as ASN.1 OPTIONAL, however in
+// most cases it is not.
+type ecPrivateKey struct {
+	Version       int
+	PrivateKey    []byte
+	NamedCurveOID asn1.ObjectIdentifier `asn1:"optional,explicit,tag:0"`
+	PublicKey     asn1.BitString        `asn1:"optional,explicit,tag:1"`
+}
+
+// ParseECPrivateKey parses an ASN.1 Elliptic Curve Private Key Structure.
+func ParseECPrivateKey(der []byte) (key *ecdsa.PrivateKey, err error) {
+	return parseECPrivateKey(nil, der)
+}
+
+// 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)},
+	})
+}
+
+// parseECPrivateKey parses an ASN.1 Elliptic Curve Private Key Structure.
+// The OID for the named curve may be provided from another source (such as
+// the PKCS8 container) - if it is provided then use this instead of the OID
+// that may exist in the EC private key structure.
+func parseECPrivateKey(namedCurveOID *asn1.ObjectIdentifier, der []byte) (key *ecdsa.PrivateKey, err error) {
+	var privKey ecPrivateKey
+	if _, err := asn1.Unmarshal(der, &privKey); err != nil {
+		return nil, errors.New("x509: failed to parse EC private key: " + err.Error())
+	}
+	if privKey.Version != ecPrivKeyVersion {
+		return nil, fmt.Errorf("x509: unknown EC private key version %d", privKey.Version)
+	}
+
+	var curve elliptic.Curve
+	if namedCurveOID != nil {
+		curve = namedCurveFromOID(*namedCurveOID)
+	} else {
+		curve = namedCurveFromOID(privKey.NamedCurveOID)
+	}
+	if curve == nil {
+		return nil, errors.New("x509: unknown elliptic curve")
+	}
+
+	k := new(big.Int).SetBytes(privKey.PrivateKey)
+	if k.Cmp(curve.Params().N) >= 0 {
+		return nil, errors.New("x509: invalid elliptic curve private key value")
+	}
+	priv := new(ecdsa.PrivateKey)
+	priv.Curve = curve
+	priv.D = k
+	priv.X, priv.Y = curve.ScalarBaseMult(privKey.PrivateKey)
+
+	return priv, nil
+}