// Verify the secret key's range and if a test message signed with it verifies OK
// Returns nil if averything looks OK
func VerifyKeyPair(priv []byte, publ []byte) error {
	const TestMessage = "Just some test message..."
	hash := Sha2Sum([]byte(TestMessage))

	pub_key, e := NewPublicKey(publ)
	if e != nil {
		return e
	}

	var key ecdsa.PrivateKey
	key.D = new(big.Int).SetBytes(priv)
	key.PublicKey = pub_key.PublicKey

	if key.D.Cmp(big.NewInt(0)) == 0 {
		return errors.New("pubkey value is zero")
	}

	if key.D.Cmp(secp256k1.N) != -1 {
		return errors.New("pubkey value is too big")
	}

	r, s, err := ecdsa.Sign(rand.Reader, &key, hash[:])
	if err != nil {
		return errors.New("ecdsa.Sign failed: " + err.Error())
	}

	ok := ecdsa.Verify(&key.PublicKey, hash[:], r, s)
	if !ok {
		return errors.New("ecdsa.Sign Verify")
	}
	return nil
}

// 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
}

// Signs a specified transaction input
func (tx *Tx) Sign(in int, pk_script []byte, hash_type byte, pubkey, priv_key []byte) error {
	if in >= len(tx.TxIn) {
		return errors.New("tx.Sign() - input index overflow")
	}

	pub_key, er := NewPublicKey(pubkey)
	if er != nil {
		return er
	}

	// Load the key (private and public)
	var key ecdsa.PrivateKey
	key.D = new(big.Int).SetBytes(priv_key)
	key.PublicKey = pub_key.PublicKey

	//Calculate proper transaction hash
	h := tx.SignatureHash(pk_script, in, hash_type)

	// Sign
	r, s, er := EcdsaSign(&key, h)
	if er != nil {
		return er
	}
	rb := r.Bytes()
	sb := s.Bytes()

	if rb[0] >= 0x80 {
		rb = append([]byte{0x00}, rb...)
	}

	if sb[0] >= 0x80 {
		sb = append([]byte{0x00}, sb...)
	}

	// Output the signing result into a buffer, in format expected by bitcoin protocol
	busig := new(bytes.Buffer)
	busig.WriteByte(0x30)
	busig.WriteByte(byte(4 + len(rb) + len(sb)))
	busig.WriteByte(0x02)
	busig.WriteByte(byte(len(rb)))
	busig.Write(rb)
	busig.WriteByte(0x02)
	busig.WriteByte(byte(len(sb)))
	busig.Write(sb)
	busig.WriteByte(0x01) // hash type

	// Output the signature and the public key into tx.ScriptSig
	buscr := new(bytes.Buffer)
	buscr.WriteByte(byte(busig.Len()))
	buscr.Write(busig.Bytes())

	buscr.WriteByte(byte(len(pubkey)))
	buscr.Write(pubkey)

	// assign sign script ot the tx:
	tx.TxIn[in].ScriptSig = buscr.Bytes()

	return nil // no error
}

func Sign(hash []byte, prv *ecdsa.PrivateKey) (sig []byte, err error) {
	if len(hash) != 32 {
		return nil, fmt.Errorf("hash is required to be exactly 32 bytes (%d)", len(hash))
	}

	sig, err = secp256k1.Sign(hash, common.LeftPadBytes(prv.D.Bytes(), prv.Params().BitSize/8))
	return
}

// New methods using proper ecdsa keys from the stdlib
func ToECDSA(prv []byte) *ecdsa.PrivateKey {
	if len(prv) == 0 {
		return nil
	}

	priv := new(ecdsa.PrivateKey)
	priv.PublicKey.Curve = secp256k1.S256()
	priv.D = common.BigD(prv)
	priv.PublicKey.X, priv.PublicKey.Y = secp256k1.S256().ScalarBaseMult(prv)
	return priv
}

// PublicPEM returns the PEM-encoded public key
func PublicPEM(key *ecdsa.PrivateKey) ([]byte, error) {
	pubBytes, err := x509.MarshalPKIXPublicKey(key.Public())
	if err != nil {
		return nil, err
	}
	pubPEM := pem.EncodeToMemory(&pem.Block{
		Type:  "PUBLIC KEY",
		Bytes: pubBytes,
	})
	return pubPEM, nil
}

func UnmarshalCertificate(data []byte) Certificate {
	priv := new(big.Int).SetBytes(data[:28])
	pub := UnmarshalPublicCertificate(data[28:])

	cert := new(ecdsa.PrivateKey)

	cert.D = priv
	cert.PublicKey = *pub

	return cert
}

func DecodeECDSAPrivateKey(b []byte) (*ecdsa.PrivateKey, error) {
	var p []big.Int
	buf := bytes.NewBuffer(b)
	dec := gob.NewDecoder(buf)
	err := dec.Decode(&p)
	if err != nil {
		return nil, err
	}
	privateKey := new(ecdsa.PrivateKey)
	privateKey.PublicKey.Curve = btcec.S256()
	privateKey.PublicKey.X = &p[0]
	privateKey.PublicKey.Y = &p[1]
	privateKey.D = &p[2]
	return privateKey, nil
}

// 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
}

func newCert(key *ecdsa.PrivateKey) (cert *x509.Certificate, err error) {
	template := &x509.Certificate{
		SerialNumber: new(big.Int).SetInt64(time.Now().UnixNano()),
		Subject: pkix.Name{
			CommonName: "nutcracker",
		},
		NotBefore:          time.Now().Add(-5 * time.Minute).UTC(),
		NotAfter:           time.Now().AddDate(1, 0, 0).UTC(),
		KeyUsage:           x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
		SignatureAlgorithm: x509.ECDSAWithSHA256,
	}
	derBytes, err := x509.CreateCertificate(rand.Reader, template, template, key.Public(), key)
	if err != nil {
		return
	}
	return x509.ParseCertificate(derBytes)
}

func readPrivateKeyECDSA(m map[string]string) (PrivateKey, error) {
	p := new(ecdsa.PrivateKey)
	p.D = big.NewInt(0)
	// TODO: validate that the required flags are present
	for k, v := range m {
		switch k {
		case "privatekey":
			v1, err := fromBase64([]byte(v))
			if err != nil {
				return nil, err
			}
			p.D.SetBytes(v1)
		case "created", "publish", "activate":
			/* not used in Go (yet) */
		}
	}
	return p, nil
}

func (pk *PrivateKey) parseECDSAPrivateKey(data []byte) (err error) {
	ecdsaPub := pk.PublicKey.PublicKey.(*ecdsa.PublicKey)
	ecdsaPriv := new(ecdsa.PrivateKey)
	ecdsaPriv.PublicKey = *ecdsaPub

	buf := bytes.NewBuffer(data)
	d, _, err := readMPI(buf)
	if err != nil {
		return
	}

	ecdsaPriv.D = new(big.Int).SetBytes(d)
	pk.PrivateKey = ecdsaPriv
	pk.Encrypted = false
	pk.encryptedData = nil

	return nil
}

func (k *RR_DNSKEY) readPrivateKeyECDSA(kv map[string]string) (PrivateKey, os.Error) {
	p := new(ecdsa.PrivateKey)
	p.D = big.NewInt(0)
	// Need to check if we have everything
	for k, v := range kv {
		switch k {
		case "privatekey:":
			v1, err := packBase64([]byte(v))
			if err != nil {
				return nil, err
			}
			p.D.SetBytes(v1)
		case "created:", "publish:", "activate:":
			/* not used in Go (yet) */
		}
	}
	return p, nil
}

// GenerateCertificate generates an X509 Certificate from a template, given a GUN
func (ucs *UnlockedCryptoService) GenerateCertificate(gun string) (*x509.Certificate, error) {
	algorithm := ucs.PrivKey.Algorithm()
	var publicKey crypto.PublicKey
	var privateKey crypto.PrivateKey
	var err error
	switch algorithm {
	case data.RSAKey:
		var rsaPrivateKey *rsa.PrivateKey
		rsaPrivateKey, err = x509.ParsePKCS1PrivateKey(ucs.PrivKey.Private())
		privateKey = rsaPrivateKey
		publicKey = rsaPrivateKey.Public()
	case data.ECDSAKey:
		var ecdsaPrivateKey *ecdsa.PrivateKey
		ecdsaPrivateKey, err = x509.ParseECPrivateKey(ucs.PrivKey.Private())
		privateKey = ecdsaPrivateKey
		publicKey = ecdsaPrivateKey.Public()
	default:
		return nil, fmt.Errorf("only RSA or ECDSA keys are currently supported. Found: %s", algorithm)
	}
	if err != nil {
		return nil, fmt.Errorf("failed to parse root key: %s (%v)", gun, err)
	}

	template, err := trustmanager.NewCertificate(gun)
	if err != nil {
		return nil, fmt.Errorf("failed to create the certificate template for: %s (%v)", gun, err)
	}

	derBytes, err := x509.CreateCertificate(rand.Reader, template, template, publicKey, privateKey)
	if err != nil {
		return nil, fmt.Errorf("failed to create the certificate for: %s (%v)", gun, err)
	}

	// Encode the new certificate into PEM
	cert, err := x509.ParseCertificate(derBytes)
	if err != nil {
		return nil, fmt.Errorf("failed to parse the certificate for key: %s (%v)", gun, err)
	}

	return cert, nil
}

// GenSignature - Debugging function to sign a message
func GenSignature(w http.ResponseWriter, r *http.Request) {
	// Returns a Public / Private Key Pair
	// Uses eliptic curve cryptography

	// Generate a public / private key pair
	privatekey := new(ecdsa.PrivateKey)

	// Generate an elliptic curve using NIST P-224
	ecurve := elliptic.P224()
	privatekey, err := ecdsa.GenerateKey(ecurve, rand.Reader)

	if err != nil {
		panic(err)
	}

	// Marshal the JSON
	privkey, _ := json.Marshal(privatekey)
	publikey, _ := json.Marshal(privatekey.Public())

	// Get the public key
	var pubkey ecdsa.PublicKey
	pubkey = privatekey.PublicKey

	// Try signing a message
	message := []byte("This is a test")
	sig1, sig2, err := ecdsa.Sign(rand.Reader, privatekey, message)

	// Try verifying the signature
	result := ecdsa.Verify(&pubkey, message, sig1, sig2)
	if result != true {
		panic("Unable to verify signature")
	}

	fmt.Fprintln(w, "Marshaled Private Key:", string(privkey))
	fmt.Fprintln(w, "Marshaled Public Key:", string(publikey))
	fmt.Fprintln(w, "Curve: ", pubkey.Curve)
	fmt.Fprintf(w, "Curve: Private: %#v\nPublic: %#v\n\nSignature:\n%v\n%v\n\nVerified: %v", privatekey, pubkey, sig1, sig2, result)

}

// Verify the secret key's range and al if a test message signed with it verifies OK
func verify_key(priv []byte, publ []byte) bool {
	const TestMessage = "Just some test message..."
	hash := btc.Sha2Sum([]byte(TestMessage))

	pub_key, e := btc.NewPublicKey(publ)
	if e != nil {
		println("NewPublicKey:", e.Error(), "\007")
		os.Exit(1)
	}

	var key ecdsa.PrivateKey
	key.D = new(big.Int).SetBytes(priv)
	key.PublicKey = pub_key.PublicKey

	if key.D.Cmp(big.NewInt(0)) == 0 {
		println("pubkey value is zero")
		return false
	}

	if key.D.Cmp(maxKeyVal) != -1 {
		println("pubkey value is too big", hex.EncodeToString(publ))
		return false
	}

	r, s, err := ecdsa.Sign(rand.Reader, &key, hash[:])
	if err != nil {
		println("ecdsa.Sign:", err.Error())
		return false
	}

	ok := ecdsa.Verify(&key.PublicKey, hash[:], r, s)
	if !ok {
		println("The key pair does not verify!")
		return false
	}
	return true
}

// NewEcdsaPrivateKey creates a new JWK from a EC-DSA private key
func NewEcdsaPrivateKey(pk *ecdsa.PrivateKey) *EcdsaPrivateKey {
	pubkey := NewEcdsaPublicKey(&pk.PublicKey)
	privkey := &EcdsaPrivateKey{EcdsaPublicKey: pubkey}
	privkey.D.SetBytes(i2osp(pk.D, pk.Params().BitSize/8))
	return privkey
}

func main() {
	id1 := "99375318-11c4-4a77-ba42-f7c08ca7b9d0"
	id2 := "ff375318-11c4-4a77-ba42-f7c08ca7b9d0"
	privkeyHex, err := ioutil.ReadFile(".gn_ecdsa")
	if err != nil {
		panic(err)
	}
	privkey, err := hex.DecodeString(string(privkeyHex[:len(privkeyHex)-1]))
	if err != nil {
		panic(err)
	}

	key := new(ecdsa.PrivateKey)
	key.D = big.NewInt(0)
	key.D.SetBytes(privkey)
	key.PublicKey.Curve = elliptic.P256()
	xb, _ := hex.DecodeString("212d26c6744803803e2f81fa117630a72eaf8a7c12f16e4e1b0188785a57c783256")
	x := big.NewInt(0)
	x.SetBytes(xb)
	key.PublicKey.X = x

	yb, _ := hex.DecodeString("b0802aac16e521569f549092c41c1b295e9ff627534d1b28fe050a37f5280ac9255")
	y := big.NewInt(0)
	y.SetBytes(yb)
	key.PublicKey.Y = y

	ids := map[string]*ecdsa.PublicKey{
		id1: &key.PublicKey,
		id2: &key.PublicKey,
	}
	node1 := gophernet.NewNode(id1, key, 100, ids)
	node2 := gophernet.NewNode(id2, key, 100, ids)

	errChan := make(chan error)
	stopChan := make(chan struct{})
	msgChan1 := make(chan *gophernet.Message, 1)
	msgChan2 := make(chan *gophernet.Message, 1)
	go gophernet.Listen(node1, ":7890", errChan, stopChan, msgChan1)
	go gophernet.Listen(node2, ":7891", errChan, stopChan, msgChan2)

	{
		log.Printf("MAIN: Giving listeners a couple seconds to start.")
		var err error
		select {
		case err = <-errChan:
			log.Printf("MAIN: Error: %v", err)
		case <-time.After(2 * time.Second):
		}

		if err != nil {
			log.Printf("MAIN: At least one error, stopping")
			close(stopChan)
			for err := range errChan {
				log.Print("MAIN: Error: %v", err)
			}
		}
	}

	c, err := net.Dial("tcp", "0.0.0.0:7891")
	if err != nil {
		panic(err)
	}
	p := node2.AddPeer(c)
	go gophernet.Handle(node2.ID, p, node2.DropPeer, node2.GetKey, stopChan, msgChan2)

	node2.Broadcast(&gophernet.Message{})

	select {
	case err = <-errChan:
		log.Printf("MAIN: Error: %v", err)
	case msg := <-msgChan1:
		log.Printf("MAIN: msgChan1: %#v", msg)
	case msg := <-msgChan2:
		log.Printf("MAIN: msgChan2: %#v", msg)
	}
}

// this function signs either a message or a raw transaction hash
func sign_message() {
	var hash []byte

	if *signhash != "" {
		var er error
		hash, er = hex.DecodeString(*signhash)
		if er != nil {
			println("Incorrect content of -hash parameter")
			println(er.Error())
			return
		}
	}

	ad2s, e := btc.NewAddrFromString(*signaddr)
	if e != nil {
		println(e.Error())
		if *signhash != "" {
			println("Always use -sign <addr> along with -hash <msghash>")
		}
		return
	}

	var privkey *ecdsa.PrivateKey
	var compr bool

	for i := range publ_addrs {
		if publ_addrs[i].Hash160 == ad2s.Hash160 {
			privkey = new(ecdsa.PrivateKey)
			pub, e := btc.NewPublicKey(publ_addrs[i].Pubkey)
			if e != nil {
				println(e.Error())
				return
			}
			privkey.PublicKey = pub.PublicKey
			privkey.D = new(big.Int).SetBytes(priv_keys[i][:])
			compr = compressed_key[i]

			// Sign raw hash?
			if hash != nil {
				txsig := new(btc.Signature)
				txsig.HashType = 0x01
				txsig.R, txsig.S, e = btc.EcdsaSign(privkey, hash)
				if e != nil {
					println(e.Error())
					return
				}
				fmt.Println("PublicKey:", hex.EncodeToString(publ_addrs[i].Pubkey))
				fmt.Println(hex.EncodeToString(txsig.Bytes()))
				return
			}

			break
		}
	}
	if privkey == nil {
		println("You do not have a private key for", ad2s.String())
		return
	}

	var msg []byte
	if *message == "" {
		msg, _ = ioutil.ReadAll(os.Stdin)
	} else {
		msg = []byte(*message)
	}

	hash = make([]byte, 32)
	btc.HashFromMessage(msg, hash)

	btcsig := new(btc.Signature)
	var sb [65]byte
	sb[0] = 27
	if compr {
		sb[0] += 4
	}

	btcsig.R, btcsig.S, e = btc.EcdsaSign(privkey, hash)
	if e != nil {
		println(e.Error())
		return
	}

	rd := btcsig.R.Bytes()
	sd := btcsig.S.Bytes()
	copy(sb[1+32-len(rd):], rd)
	copy(sb[1+64-len(sd):], sd)

	rpk := btcsig.RecoverPublicKey(hash[:], 0)
	sa := btc.NewAddrFromPubkey(rpk.Bytes(compr), ad2s.Version)
	if sa.Hash160 == ad2s.Hash160 {
		fmt.Println(base64.StdEncoding.EncodeToString(sb[:]))
		return
	}

	rpk = btcsig.RecoverPublicKey(hash[:], 1)
	sa = btc.NewAddrFromPubkey(rpk.Bytes(compr), ad2s.Version)
	if sa.Hash160 == ad2s.Hash160 {
		sb[0]++
		fmt.Println(base64.StdEncoding.EncodeToString(sb[:]))
//.........这里部分代码省略.........

func sign_message() {
	ad2s, e := btc.NewAddrFromString(*signaddr)
	if e != nil {
		println(e.Error())
		return
	}

	var privkey *ecdsa.PrivateKey
	for i := range publ_addrs {
		if publ_addrs[i].Hash160 == ad2s.Hash160 {
			privkey = new(ecdsa.PrivateKey)
			pub, e := btc.NewPublicKey(publ_addrs[i].Pubkey)
			if e != nil {
				println(e.Error())
				return
			}
			privkey.PublicKey = pub.PublicKey
			privkey.D = new(big.Int).SetBytes(priv_keys[i][:])
			break
		}
	}
	if privkey == nil {
		println("You do not have a private key for", ad2s.String())
		return
	}

	var msg []byte
	if *message == "" {
		msg, _ = ioutil.ReadAll(os.Stdin)
	} else {
		msg = []byte(*message)
	}

	hash := make([]byte, 32)
	btc.HashFromMessage(msg, hash)

	btcsig := new(btc.Signature)
	var sb [65]byte
	sb[0] = 27
	if !*uncompressed {
		sb[0] += 4
	}

	btcsig.R, btcsig.S, e = ecdsa_Sign(privkey, hash)
	if e != nil {
		println(e.Error())
		return
	}

	rd := btcsig.R.Bytes()
	sd := btcsig.S.Bytes()
	copy(sb[1+32-len(rd):], rd)
	copy(sb[1+64-len(sd):], sd)

	rpk := btcsig.RecoverPublicKey(hash[:], 0)
	sa := btc.NewAddrFromPubkey(rpk.Bytes(!*uncompressed), ad2s.Version)
	if sa.Hash160 == ad2s.Hash160 {
		fmt.Println(base64.StdEncoding.EncodeToString(sb[:]))
		return
	}

	rpk = btcsig.RecoverPublicKey(hash[:], 1)
	sa = btc.NewAddrFromPubkey(rpk.Bytes(!*uncompressed), ad2s.Version)
	if sa.Hash160 == ad2s.Hash160 {
		sb[0]++
		fmt.Println(base64.StdEncoding.EncodeToString(sb[:]))
		return
	}
	println("Something went wrong. The message has not been signed.")
}