func TestKeyGenECDSAOpts(t *testing.T) {
	// Curve P256
	k, err := currentBCCSP.KeyGen(&bccsp.ECDSAP256KeyGenOpts{Temporary: false})
	if err != nil {
		t.Fatalf("Failed generating ECDSA P256 key [%s]", err)
	}
	if k == nil {
		t.Fatal("Failed generating ECDSA P256 key. Key must be different from nil")
	}
	if !k.Private() {
		t.Fatal("Failed generating ECDSA P256 key. Key should be private")
	}
	if k.Symmetric() {
		t.Fatal("Failed generating ECDSA P256 key. Key should be asymmetric")
	}

	ecdsaKey := k.(*ecdsaPrivateKey).privKey
	if !elliptic.P256().IsOnCurve(ecdsaKey.X, ecdsaKey.Y) {
		t.Fatal("P256 generated key in invalid. The public key must be on the P256 curve.")
	}
	if elliptic.P256() != ecdsaKey.Curve {
		t.Fatal("P256 generated key in invalid. The curve must be P256.")
	}
	if ecdsaKey.D.Cmp(big.NewInt(0)) == 0 {
		t.Fatal("P256 generated key in invalid. Private key must be different from 0.")
	}

	// Curve P384
	k, err = currentBCCSP.KeyGen(&bccsp.ECDSAP384KeyGenOpts{Temporary: false})
	if err != nil {
		t.Fatalf("Failed generating ECDSA P384 key [%s]", err)
	}
	if k == nil {
		t.Fatal("Failed generating ECDSA P384 key. Key must be different from nil")
	}
	if !k.Private() {
		t.Fatal("Failed generating ECDSA P384 key. Key should be private")
	}
	if k.Symmetric() {
		t.Fatal("Failed generating ECDSA P384 key. Key should be asymmetric")
	}

	ecdsaKey = k.(*ecdsaPrivateKey).privKey
	if !elliptic.P384().IsOnCurve(ecdsaKey.X, ecdsaKey.Y) {
		t.Fatal("P256 generated key in invalid. The public key must be on the P384 curve.")
	}
	if elliptic.P384() != ecdsaKey.Curve {
		t.Fatal("P256 generated key in invalid. The curve must be P384.")
	}
	if ecdsaKey.D.Cmp(big.NewInt(0)) == 0 {
		t.Fatal("P256 generated key in invalid. Private key must be different from 0.")
	}

}

func (ca *CA) createCAKeyPair(name string) *ecdsa.PrivateKey {
	Trace.Println("Creating CA key pair.")

	curve := elliptic.P384()

	priv, err := ecdsa.GenerateKey(curve, rand.Reader)
	if err == nil {
		raw, _ := x509.MarshalECPrivateKey(priv)
		cooked := pem.EncodeToMemory(
			&pem.Block{
				Type:  "ECDSA PRIVATE KEY",
				Bytes: raw,
			})
		err := ioutil.WriteFile(ca.path+"/"+name+".priv", cooked, 0644)
		if err != nil {
			Panic.Panicln(err)
		}

		raw, _ = x509.MarshalPKIXPublicKey(&priv.PublicKey)
		cooked = pem.EncodeToMemory(
			&pem.Block{
				Type:  "ECDSA PUBLIC KEY",
				Bytes: raw,
			})
		err = ioutil.WriteFile(ca.path+"/"+name+".pub", cooked, 0644)
		if err != nil {
			Panic.Panicln(err)
		}
	}
	if err != nil {
		Panic.Panicln(err)
	}

	return priv
}

func init() {
	// This is the group called diffie-hellman-group1-sha1 in RFC
	// 4253 and Oakley Group 2 in RFC 2409.
	p, _ := new(big.Int).SetString("FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7EDEE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381FFFFFFFFFFFFFFFF", 16)
	kexAlgoMap[kexAlgoDH1SHA1] = &dhGroup{
		g: new(big.Int).SetInt64(2),
		p: p,
	}

	// This is the group called diffie-hellman-group14-sha1 in RFC
	// 4253 and Oakley Group 14 in RFC 3526.
	p, _ = new(big.Int).SetString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

	kexAlgoMap[kexAlgoDH14SHA1] = &dhGroup{
		g: new(big.Int).SetInt64(2),
		p: p,
	}

	kexAlgoMap[kexAlgoECDH521] = &ecdh{elliptic.P521()}
	kexAlgoMap[kexAlgoECDH384] = &ecdh{elliptic.P384()}
	kexAlgoMap[kexAlgoECDH256] = &ecdh{elliptic.P256()}
	kexAlgoMap[kexAlgoCurve25519SHA256] = &curve25519sha256{}

	kexAlgoMap[kexAlgoDHGEXSHA1] = &dhGEXSHA1{}
}

func marshalECDSAKey(priv *ecdsa.PrivateKey) (out []byte, err error) {
	var eckey ecPrivateKey

	eckey.Version = 1
	eckey.PrivateKey = priv.D.Bytes()
	switch priv.PublicKey.Curve {
	case elliptic.P256():
		eckey.NamedCurveOID = oidNamedCurveP256
	case elliptic.P384():
		eckey.NamedCurveOID = oidNamedCurveP384
	case elliptic.P521():
		eckey.NamedCurveOID = oidNamedCurveP521
	default:
		err = ErrInvalidPrivateKey
	}

	pkey := elliptic.Marshal(priv.PublicKey.Curve, priv.PublicKey.X,
		priv.PublicKey.Y)
	if pkey == nil {
		err = ErrInvalidPrivateKey
		return
	}

	eckey.PublicKey = asn1.BitString{
		BitLength: len(pkey) * 8,
		Bytes:     pkey,
	}
	out, err = asn1.Marshal(eckey)
	return
}

// parseECDSA parses an ECDSA key according to RFC 5656, section 3.1.
func parseECDSA(in []byte) (out PublicKey, rest []byte, err error) {
	var identifier []byte
	var ok bool
	if identifier, in, ok = parseString(in); !ok {
		return nil, nil, errShortRead
	}

	key := new(ecdsa.PublicKey)

	switch string(identifier) {
	case "nistp256":
		key.Curve = elliptic.P256()
	case "nistp384":
		key.Curve = elliptic.P384()
	case "nistp521":
		key.Curve = elliptic.P521()
	default:
		return nil, nil, errors.New("ssh: unsupported curve")
	}

	var keyBytes []byte
	if keyBytes, in, ok = parseString(in); !ok {
		return nil, nil, errShortRead
	}

	key.X, key.Y = elliptic.Unmarshal(key.Curve, keyBytes)
	if key.X == nil || key.Y == nil {
		return nil, nil, errors.New("ssh: invalid curve point")
	}
	return (*ecdsaPublicKey)(key), in, nil
}

func TestECDSAVerifierOtherCurves(t *testing.T) {
	curves := []elliptic.Curve{elliptic.P256(), elliptic.P384(), elliptic.P521()}

	for _, curve := range curves {
		ecdsaPrivKey, err := ecdsa.GenerateKey(curve, rand.Reader)

		// Get a DER-encoded representation of the PublicKey
		ecdsaPubBytes, err := x509.MarshalPKIXPublicKey(&ecdsaPrivKey.PublicKey)
		assert.NoError(t, err, "failed to marshal public key")

		// Get a DER-encoded representation of the PrivateKey
		ecdsaPrivKeyBytes, err := x509.MarshalECPrivateKey(ecdsaPrivKey)
		assert.NoError(t, err, "failed to marshal private key")

		testECDSAPubKey := data.NewECDSAPublicKey(ecdsaPubBytes)
		testECDSAKey, err := data.NewECDSAPrivateKey(testECDSAPubKey, ecdsaPrivKeyBytes)
		assert.NoError(t, err, "failed to read private key")

		// Sign some data using ECDSA
		message := []byte("test data for signing")
		hashed := sha256.Sum256(message)
		signedData, err := ecdsaSign(testECDSAKey, hashed[:])
		assert.NoError(t, err)

		// Create and call Verify on the verifier
		ecdsaVerifier := ECDSAVerifier{}
		err = ecdsaVerifier.Verify(testECDSAKey, signedData, message)
		assert.NoError(t, err, "expecting success but got error while verifying data using ECDSA")

		// Make sure an invalid signature fails verification
		signedData[0]++
		err = ecdsaVerifier.Verify(testECDSAKey, signedData, message)
		assert.Error(t, err, "expecting error but got success while verifying data using ECDSA")
	}
}

func (ctrl *Controller) AddHostKeyFromCluster(host string) error {
	generate := func() (string, error) {
		// Generate an ECDSA key.
		key, err := ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
		if err != nil {
			return "", err
		}
		derBytes, err := x509.MarshalECPrivateKey(key)
		if err != nil {
			return "", err
		}
		w := &bytes.Buffer{}
		if err := pem.Encode(w, &pem.Block{Type: "EC PRIVATE KEY", Bytes: derBytes}); err != nil {
			return "", err
		}
		return w.String(), nil
	}
	pemString, err := ctrl.cluster.GetValueWithDefault(fmt.Sprintf("console/%s", host), generate)
	if err != nil {
		return fmt.Errorf("failed to get/generate host key: %s", err)
	}

	signer, err := ssh.ParsePrivateKey([]byte(pemString))
	if err != nil {
		return fmt.Errorf("failed to parse host key: %s", err)
	}

	ctrl.config.AddHostKey(signer)
	return nil
}

func init() {
	raw256, _ := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
	ecdsaKey, _ = NewSignerFromKey(raw256)

	raw384, _ := ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
	ecdsa384Key, _ = NewSignerFromKey(raw384)

	raw521, _ := ecdsa.GenerateKey(elliptic.P521(), rand.Reader)
	ecdsa521Key, _ = NewSignerFromKey(raw521)

	// Create a cert and sign it for use in tests.
	testCert := &OpenSSHCertV01{
		Nonce:           []byte{}, // To pass reflect.DeepEqual after marshal & parse, this must be non-nil
		Key:             ecdsaKey.PublicKey(),
		ValidPrincipals: []string{"gopher1", "gopher2"}, // increases test coverage
		ValidAfter:      0,                              // unix epoch
		ValidBefore:     maxUint64,                      // The end of currently representable time.
		Reserved:        []byte{},                       // To pass reflect.DeepEqual after marshal & parse, this must be non-nil
		SignatureKey:    rsaKey.PublicKey(),
	}
	sigBytes, _ := rsaKey.Sign(rand.Reader, testCert.BytesForSigning())
	testCert.Signature = &signature{
		Format: testCert.SignatureKey.PublicKeyAlgo(),
		Blob:   sigBytes,
	}
	testCertKey = &testSigner{
		Signer: ecdsaKey,
		pub:    testCert,
	}
}

// DefaultSigAlgo returns an appropriate X.509 signature algorithm given the
// CA's private key.
func DefaultSigAlgo(priv interface{}) x509.SignatureAlgorithm {
	switch priv := priv.(type) {
	case *rsa.PrivateKey:
		keySize := priv.N.BitLen()
		switch {
		case keySize >= 4096:
			return x509.SHA512WithRSA
		case keySize >= 3072:
			return x509.SHA384WithRSA
		case keySize >= 2048:
			return x509.SHA256WithRSA
		default:
			return x509.SHA1WithRSA
		}
	case *ecdsa.PrivateKey:
		switch priv.Curve {
		case elliptic.P256():
			return x509.ECDSAWithSHA256
		case elliptic.P384():
			return x509.ECDSAWithSHA384
		case elliptic.P521():
			return x509.ECDSAWithSHA512
		default:
			return x509.ECDSAWithSHA1
		}
	default:
		return x509.UnknownSignatureAlgorithm
	}
}

// Sexp returns a well-formed S-expression for k
func (k *PrivateKey) Sexp() (s sexprs.Sexp) {
	l := make(sexprs.List, 2)
	l[0] = sexprs.Atom{Value: []byte("private-key")}
	ll := make(sexprs.List, 5)
	l[1] = ll
	ll[0] = sexprs.Atom{Value: []byte("ecdsa-sha2")}
	c := make(sexprs.List, 2)
	ll[1] = c
	c[0] = sexprs.Atom{Value: []byte("curve")}
	switch k.Curve {
	case elliptic.P256():
		c[1] = sexprs.Atom{Value: []byte("p256")}
	case elliptic.P384():
		c[1] = sexprs.Atom{Value: []byte("p384")}
	default:
		return nil
	}
	x := make(sexprs.List, 2)
	ll[2] = x
	x[0] = sexprs.Atom{Value: []byte("x")}
	x[1] = sexprs.Atom{Value: k.X.Bytes()}
	y := make(sexprs.List, 2)
	ll[3] = y
	y[0] = sexprs.Atom{Value: []byte("y")}
	y[1] = sexprs.Atom{Value: k.Y.Bytes()}
	d := make(sexprs.List, 2)
	ll[4] = d
	d[0] = sexprs.Atom{Value: []byte("d")}
	d[1] = sexprs.Atom{Value: k.D.Bytes()}
	return l
}

func (j *jws) signContent(content []byte) (*jose.JsonWebSignature, error) {

	var alg jose.SignatureAlgorithm
	switch k := j.privKey.(type) {
	case *rsa.PrivateKey:
		alg = jose.RS256
	case *ecdsa.PrivateKey:
		if k.Curve == elliptic.P256() {
			alg = jose.ES256
		} else if k.Curve == elliptic.P384() {
			alg = jose.ES384
		}
	}

	signer, err := jose.NewSigner(alg, j.privKey)
	if err != nil {
		return nil, err
	}
	signer.SetNonceSource(j)

	signed, err := signer.Sign(content)
	if err != nil {
		return nil, err
	}
	return signed, nil
}

func TestSignWithP384(t *testing.T) {
	message := []byte("Hello, world!")

	key, err := ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
	if err != nil {
		t.Error(err)
		return
	}

	signature, err := Sign(message, key)
	if err != nil {
		t.Error(err)
		return
	}

	if !Verify(message, signature, &key.PublicKey) {
		t.Error("signature was not correct")
		return
	}

	message[0] ^= 0xff
	if Verify(message, signature, &key.PublicKey) {
		t.Error("signature was good for altered message")
	}
}

// Compute the priority of different key algorithm based performance and security
// ECDSA>RSA>DSA>Unknown
func keyAlgoPriority(cert *x509.Certificate) int {
	switch cert.PublicKeyAlgorithm {
	case x509.ECDSA:
		switch cert.PublicKey.(*ecdsa.PublicKey).Curve {
		case elliptic.P256():
			return 100
		case elliptic.P384():
			return 120
		case elliptic.P521():
			return 140
		default:
			return 100
		}
	case x509.RSA:
		switch cert.PublicKey.(*rsa.PublicKey).N.BitLen() {
		case 4096:
			return 70
		case 3072:
			return 50
		case 2048:
			return 30
		// key size <= 1024 are discouraged.
		default:
			return 0
		}
	// we do not want to bundle a DSA cert.
	case x509.DSA:
		return 0
	default:
		return 0
	}
}

// keyAlgoUbiquity compute the ubiquity of the cert's public key algorithm
// RSA, DSA>ECDSA>Unknown
func keyAlgoUbiquity(cert *x509.Certificate) KeyAlgoUbiquity {
	switch cert.PublicKeyAlgorithm {
	case x509.ECDSA:
		switch cert.PublicKey.(*ecdsa.PublicKey).Curve {
		case elliptic.P256():
			return ECDSA256Ubiquity
		case elliptic.P384():
			return ECDSA384Ubiquity
		case elliptic.P521():
			return ECDSA521Ubiquity
		default:
			return UnknownAlgoUbiquity
		}
	case x509.RSA:
		if cert.PublicKey.(*rsa.PublicKey).N.BitLen() >= 1024 {
			return RSAUbiquity
		} else {
			return UnknownAlgoUbiquity
		}
	case x509.DSA:
		return DSAUbiquity
	default:
		return UnknownAlgoUbiquity
	}
}

// Generate generates a key as specified in the request. Currently,
// only ECDSA and RSA are supported.
func (kr *BasicKeyRequest) Generate() (crypto.PrivateKey, error) {
	log.Debugf("generate key from request: algo=%s, size=%d", kr.Algo(), kr.Size())
	switch kr.Algo() {
	case "rsa":
		if kr.Size() < 2048 {
			return nil, errors.New("RSA key is too weak")
		}
		if kr.Size() > 8192 {
			return nil, errors.New("RSA key size too large")
		}
		return rsa.GenerateKey(rand.Reader, kr.Size())
	case "ecdsa":
		var curve elliptic.Curve
		switch kr.Size() {
		case curveP256:
			curve = elliptic.P256()
		case curveP384:
			curve = elliptic.P384()
		case curveP521:
			curve = elliptic.P521()
		default:
			return nil, errors.New("invalid curve")
		}
		return ecdsa.GenerateKey(curve, rand.Reader)
	default:
		return nil, errors.New("invalid algorithm")
	}
}

// Sign creates a JWT using the signing key.
func (k Keys) Sign(payload []byte) (jws string, err error) {
	if k.SigningKey == nil {
		return "", fmt.Errorf("no key to sign payload with")
	}
	signingKey := jose.SigningKey{Key: k.SigningKey}

	switch key := k.SigningKey.Key.(type) {
	case *rsa.PrivateKey:
		// TODO(ericchiang): Allow different cryptographic hashes.
		signingKey.Algorithm = jose.RS256
	case *ecdsa.PrivateKey:
		switch key.Params() {
		case elliptic.P256().Params():
			signingKey.Algorithm = jose.ES256
		case elliptic.P384().Params():
			signingKey.Algorithm = jose.ES384
		case elliptic.P521().Params():
			signingKey.Algorithm = jose.ES512
		default:
			return "", errors.New("unsupported ecdsa curve")
		}
	}

	signer, err := jose.NewSigner(signingKey, &jose.SignerOptions{})
	if err != nil {
		return "", fmt.Errorf("new signier: %v", err)
	}
	signature, err := signer.Sign(payload)
	if err != nil {
		return "", fmt.Errorf("signing payload: %v", err)
	}
	return signature.CompactSerialize()
}

// parseECDSA parses an ECDSA key according to RFC 5656, section 3.1.
func parseECDSA(in []byte) (out *ecdsa.PublicKey, rest []byte, ok bool) {
	var identifier []byte
	if identifier, in, ok = parseString(in); !ok {
		return
	}

	key := new(ecdsa.PublicKey)

	switch string(identifier) {
	case "nistp256":
		key.Curve = elliptic.P256()
	case "nistp384":
		key.Curve = elliptic.P384()
	case "nistp521":
		key.Curve = elliptic.P521()
	default:
		ok = false
		return
	}

	var keyBytes []byte
	if keyBytes, in, ok = parseString(in); !ok {
		return
	}

	key.X, key.Y = elliptic.Unmarshal(key.Curve, keyBytes)
	if key.X == nil || key.Y == nil {
		ok = false
		return
	}
	return key, in, ok
}

func NewECDSAPublicKey(creationTime time.Time, pub *ecdsa.PublicKey) *PublicKey {
	pk := &PublicKey{
		CreationTime: creationTime,
		PubKeyAlgo:   PubKeyAlgoECDSA,
		PublicKey:    pub,
		ec:           new(ecdsaKey),
	}

	switch pub.Curve {
	case elliptic.P256():
		pk.ec.oid = oidCurveP256
	case elliptic.P384():
		pk.ec.oid = oidCurveP384
	case elliptic.P521():
		pk.ec.oid = oidCurveP521
	default:
		panic("unknown elliptic curve")
	}

	pk.ec.p.bytes = elliptic.Marshal(pub.Curve, pub.X, pub.Y)
	pk.ec.p.bitLength = uint16(8 * len(pk.ec.p.bytes))

	pk.setFingerPrintAndKeyId()
	return pk
}

// parseECDSA parses an ECDSA key according to RFC 5656, section 3.1.
func parseECDSA(in []byte) (out PublicKey, rest []byte, err error) {
	var w struct {
		Curve    string
		KeyBytes []byte
		Rest     []byte `ssh:"rest"`
	}

	if err := Unmarshal(in, &w); err != nil {
		return nil, nil, err
	}

	key := new(ecdsa.PublicKey)

	switch w.Curve {
	case "nistp256":
		key.Curve = elliptic.P256()
	case "nistp384":
		key.Curve = elliptic.P384()
	case "nistp521":
		key.Curve = elliptic.P521()
	default:
		return nil, nil, errors.New("ssh: unsupported curve")
	}

	key.X, key.Y = elliptic.Unmarshal(key.Curve, w.KeyBytes)
	if key.X == nil || key.Y == nil {
		return nil, nil, errors.New("ssh: invalid curve point")
	}
	return (*ecdsaPublicKey)(key), w.Rest, nil
}

func evalECDSASHA2PrivateKeyTerms(l sexprs.List) (k PrivateKey, err error) {
	curve, err := evalCurve(l[1])
	if err != nil {
		return k, err
	}
	switch curve {
	case "p256":
		k.Curve = elliptic.P256()
	case "p384":
		k.Curve = elliptic.P384()
	default:
		return k, fmt.Errorf("Curve must be either 'p256' or 'p384'")
	}
	k.X, err = evalNamedBigInt("x", l[2])
	if err != nil {
		return k, err
	}
	k.Y, err = evalNamedBigInt("y", l[3])
	if err != nil {
		return k, err
	}
	k.D, err = evalNamedBigInt("d", l[4])
	if err != nil {
		return k, err
	}
	return k, nil
}