1 files changed, 136 insertions, 0 deletions
diff --git a/src/crypto/x509/sec1.go b/src/crypto/x509/sec1.go
new file mode 100644
index 0000000..6bfba0d
--- /dev/null
+++ b/src/crypto/x509/sec1.go
@@ -0,0 +1,136 @@
+// 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/ecdh"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"encoding/asn1"
+	"errors"
+	"fmt"
+	"math/big"
+)
+
+const ecPrivKeyVersion = 1
+
+// ecPrivateKey reflects an ASN.1 Elliptic Curve Private Key Structure.
+// References:
+//
+//	RFC 5915
+//	SEC1 - http://www.secg.org/sec1-v2.pdf
+//
+// Per RFC 5915 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 EC private key in SEC 1, ASN.1 DER form.
+//
+// This kind of key is commonly encoded in PEM blocks of type "EC PRIVATE KEY".
+func ParseECPrivateKey(der []byte) (*ecdsa.PrivateKey, error) {
+	return parseECPrivateKey(nil, der)
+}
+
+// MarshalECPrivateKey converts an EC private key to SEC 1, ASN.1 DER form.
+//
+// This kind of key is commonly encoded in PEM blocks of type "EC PRIVATE KEY".
+// For a more flexible key format which is not EC specific, use
+// MarshalPKCS8PrivateKey.
+func MarshalECPrivateKey(key *ecdsa.PrivateKey) ([]byte, error) {
+	oid, ok := oidFromNamedCurve(key.Curve)
+	if !ok {
+		return nil, errors.New("x509: unknown elliptic curve")
+	}
+
+	return marshalECPrivateKeyWithOID(key, oid)
+}
+
+// marshalECPrivateKeyWithOID marshals an EC private key into ASN.1, DER format and
+// sets the curve ID to the given OID, or omits it if OID is nil.
+func marshalECPrivateKeyWithOID(key *ecdsa.PrivateKey, oid asn1.ObjectIdentifier) ([]byte, error) {
+	if !key.Curve.IsOnCurve(key.X, key.Y) {
+		return nil, errors.New("invalid elliptic key public key")
+	}
+	privateKey := make([]byte, (key.Curve.Params().N.BitLen()+7)/8)
+	return asn1.Marshal(ecPrivateKey{
+		Version:       1,
+		PrivateKey:    key.D.FillBytes(privateKey),
+		NamedCurveOID: oid,
+		PublicKey:     asn1.BitString{Bytes: elliptic.Marshal(key.Curve, key.X, key.Y)},
+	})
+}
+
+// marshalECDHPrivateKey marshals an EC private key into ASN.1, DER format
+// suitable for NIST curves.
+func marshalECDHPrivateKey(key *ecdh.PrivateKey) ([]byte, error) {
+	return asn1.Marshal(ecPrivateKey{
+		Version:    1,
+		PrivateKey: key.Bytes(),
+		PublicKey:  asn1.BitString{Bytes: key.PublicKey().Bytes()},
+	})
+}
+
+// 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 {
+		if _, err := asn1.Unmarshal(der, &pkcs8{}); err == nil {
+			return nil, errors.New("x509: failed to parse private key (use ParsePKCS8PrivateKey instead for this key format)")
+		}
+		if _, err := asn1.Unmarshal(der, &pkcs1PrivateKey{}); err == nil {
+			return nil, errors.New("x509: failed to parse private key (use ParsePKCS1PrivateKey instead for this key format)")
+		}
+		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)
+	curveOrder := curve.Params().N
+	if k.Cmp(curveOrder) >= 0 {
+		return nil, errors.New("x509: invalid elliptic curve private key value")
+	}
+	priv := new(ecdsa.PrivateKey)
+	priv.Curve = curve
+	priv.D = k
+
+	privateKey := make([]byte, (curveOrder.BitLen()+7)/8)
+
+	// Some private keys have leading zero padding. This is invalid
+	// according to [SEC1], but this code will ignore it.
+	for len(privKey.PrivateKey) > len(privateKey) {
+		if privKey.PrivateKey[0] != 0 {
+			return nil, errors.New("x509: invalid private key length")
+		}
+		privKey.PrivateKey = privKey.PrivateKey[1:]
+	}
+
+	// Some private keys remove all leading zeros, this is also invalid
+	// according to [SEC1] but since OpenSSL used to do this, we ignore
+	// this too.
+	copy(privateKey[len(privateKey)-len(privKey.PrivateKey):], privKey.PrivateKey)
+	priv.X, priv.Y = curve.ScalarBaseMult(privateKey)
+
+	return priv, nil
+}