// 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 *bitecdsa.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 *bitelliptic.BitCurve
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.N) >= 0 {
return nil, errors.New("x509: invalid elliptic curve private key value")
}
return bitecdsa.NewKeyFromInt(curve, k), nil
}
func (k *Key) Sign(data []byte) (*big.Int, *big.Int) {
key := bitecdsa.NewKeyFromInt(bitelliptic.S256(), k.prvKey)
r, s, err := bitecdsa.Sign(rand.Reader, key, data)
if err != nil {
panic(err.Error())
}
return r, s
}
func privateToPublic(d *big.Int) point {
key := bitecdsa.NewKeyFromInt(bitelliptic.S256(), d)
return point{key.X, key.Y}
}