Beispiel #1
0
// 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
}
Beispiel #2
0
// 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)
	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
}