Function parseECDSA

internal/sshutil/sshutil.go:186–230

parseECDSA parses an ECDSA key according to RFC 5656, section 3.1. This function is based on the one in golang.org/x/crypto/ssh.

(in []byte)

//
// This function is based on the one in golang.org/x/crypto/ssh.
func parseECDSA(in []byte) (*ecdsa.PublicKey, error) {
	var w struct {
		Name  string
		Curve string
		Key   []byte
	}

	if err := ssh.Unmarshal(in, &w); err != nil {
		return nil, errors.Wrap(err, "error unmarshaling public key")
	}

	var (
		key   *ecdh.PublicKey
		curve elliptic.Curve
		size  int
		err   error
	)

	switch w.Curve {
	case "nistp256":
		curve = elliptic.P256()
		key, err = ecdh.P256().NewPublicKey(w.Key)
		size = 32
	case "nistp384":
		curve = elliptic.P384()
		key, err = ecdh.P384().NewPublicKey(w.Key)
		size = 48
	case "nistp521":
		curve = elliptic.P521()
		key, err = ecdh.P521().NewPublicKey(w.Key)
		size = 66
	default:
		return nil, errors.Errorf("unsupported curve %s", w.Curve)
	}

	if err != nil {
		return nil, fmt.Errorf("failed to create key: %w", err)
	}

	return &ecdsa.PublicKey{
		Curve: curve,
		X:     big.NewInt(0).SetBytes(key.Bytes()[1 : size+1]),
		Y:     big.NewInt(0).SetBytes(key.Bytes()[size+1:]),
	}, nil
}

func parseED25519(in []byte) (ed25519.PublicKey, error) {
	var w struct {