func SignMessage(privKey string, message string, compress bool) string {
	prefixBytes := []byte("Bitcoin Signed Message:\n")
	messageBytes := []byte(message)
	bytes := []byte{}
	bytes = append(bytes, byte(len(prefixBytes)))
	bytes = append(bytes, prefixBytes...)
	bytes = append(bytes, byte(len(messageBytes)))
	bytes = append(bytes, messageBytes...)
	privKeyBytes := HexDecode(privKey)
	x, y := btcec.S256().ScalarBaseMult(privKeyBytes)
	ecdsaPubKey := ecdsa.PublicKey{
		Curve: btcec.S256(),
		X:     x,
		Y:     y,
	}
	ecdsaPrivKey := &ecdsa.PrivateKey{
		PublicKey: ecdsaPubKey,
		D:         new(big.Int).SetBytes(privKeyBytes),
	}
	sigbytes, err := btcec.SignCompact(btcec.S256(), ecdsaPrivKey, btcwire.DoubleSha256(bytes), compress)
	if err != nil {
		panic(err)
	}
	return base64.StdEncoding.EncodeToString(sigbytes)
}

func TestEncodeDecodeWIF(t *testing.T) {
	priv1, _ := btcec.PrivKeyFromBytes(btcec.S256(), []byte{
		0x0c, 0x28, 0xfc, 0xa3, 0x86, 0xc7, 0xa2, 0x27,
		0x60, 0x0b, 0x2f, 0xe5, 0x0b, 0x7c, 0xae, 0x11,
		0xec, 0x86, 0xd3, 0xbf, 0x1f, 0xbe, 0x47, 0x1b,
		0xe8, 0x98, 0x27, 0xe1, 0x9d, 0x72, 0xaa, 0x1d})

	priv2, _ := btcec.PrivKeyFromBytes(btcec.S256(), []byte{
		0xdd, 0xa3, 0x5a, 0x14, 0x88, 0xfb, 0x97, 0xb6,
		0xeb, 0x3f, 0xe6, 0xe9, 0xef, 0x2a, 0x25, 0x81,
		0x4e, 0x39, 0x6f, 0xb5, 0xdc, 0x29, 0x5f, 0xe9,
		0x94, 0xb9, 0x67, 0x89, 0xb2, 0x1a, 0x03, 0x98})

	wif1, err := NewWIF(priv1, &btcnet.MainNetParams, false)
	if err != nil {
		t.Fatal(err)
	}
	wif2, err := NewWIF(priv2, &btcnet.TestNet3Params, true)
	if err != nil {
		t.Fatal(err)
	}

	tests := []struct {
		wif     *WIF
		encoded string
	}{
		{
			wif1,
			"5HueCGU8rMjxEXxiPuD5BDku4MkFqeZyd4dZ1jvhTVqvbTLvyTJ",
		},
		{
			wif2,
			"cV1Y7ARUr9Yx7BR55nTdnR7ZXNJphZtCCMBTEZBJe1hXt2kB684q",
		},
	}

	for _, test := range tests {
		// Test that encoding the WIF structure matches the expected string.
		s := test.wif.String()
		if s != test.encoded {
			t.Errorf("TestEncodeDecodePrivateKey failed: want '%s', got '%s'",
				test.encoded, s)
			continue
		}

		// Test that decoding the expected string results in the original WIF
		// structure.
		w, err := DecodeWIF(test.encoded)
		if err != nil {
			t.Error(err)
			continue
		}
		if got := w.String(); got != test.encoded {
			t.Errorf("NewWIF failed: want '%v', got '%v'", test.wif, got)
		}
	}
}

// Verifies a hash using DER encoded signature
func Verify(pubKey, signature, hash []byte) (bool, error) {
	sig, err := btcec.ParseDERSignature(signature, btcec.S256())
	if err != nil {
		return false, err
	}
	pk, err := btcec.ParsePubKey(pubKey, btcec.S256())
	if err != nil {
		return false, nil
	}
	return sig.Verify(hash, pk), nil
}

func TestPrivKeys(t *testing.T) {
	for _, test := range privKeyTests {
		_, pub := btcec.PrivKeyFromBytes(btcec.S256(), test.key)

		_, err := btcec.ParsePubKey(
			pub.SerializeUncompressed(), btcec.S256())
		if err != nil {
			t.Errorf("%s privkey: %v", test.name, err)
			continue
		}
	}
}

func PubKeyBytesFromPrivKeyBytes(privKeyBytes []byte, compress bool) (pubKeyBytes []byte) {
	x, y := btcec.S256().ScalarBaseMult(privKeyBytes)
	pub := (*btcec.PublicKey)(&ecdsa.PublicKey{
		Curve: btcec.S256(),
		X:     x,
		Y:     y,
	})

	if compress {
		return pub.SerializeCompressed()
	}
	return pub.SerializeUncompressed()
}

// NewKeyFromString returns a new extended key instance from a base58-encoded
// extended key.
func NewKeyFromString(key string) (*ExtendedKey, error) {
	// The base58-decoded extended key must consist of a serialized payload
	// plus an additional 4 bytes for the checksum.
	decoded := btcutil.Base58Decode(key)
	if len(decoded) != serializedKeyLen+4 {
		return nil, ErrInvalidKeyLen
	}

	// The serialized format is:
	//   version (4) || depth (1) || parent fingerprint (4)) ||
	//   child num (4) || chain code (32) || key data (33) || checksum (4)

	// Split the payload and checksum up and ensure the checksum matches.
	payload := decoded[:len(decoded)-4]
	checkSum := decoded[len(decoded)-4:]
	expectedCheckSum := btcwire.DoubleSha256(payload)[:4]
	if !bytes.Equal(checkSum, expectedCheckSum) {
		return nil, ErrBadChecksum
	}

	// Deserialize each of the payload fields.
	version := payload[:4]
	depth := uint16(payload[4:5][0])
	parentFP := payload[5:9]
	childNum := binary.BigEndian.Uint32(payload[9:13])
	chainCode := payload[13:45]
	keyData := payload[45:78]

	// The key data is a private key if it starts with 0x00.  Serialized
	// compressed pubkeys either start with 0x02 or 0x03.
	isPrivate := keyData[0] == 0x00
	if isPrivate {
		// Ensure the private key is valid.  It must be within the range
		// of the order of the secp256k1 curve and not be 0.
		keyData = keyData[1:]
		keyNum := new(big.Int).SetBytes(keyData)
		if keyNum.Cmp(btcec.S256().N) >= 0 || keyNum.Sign() == 0 {
			return nil, ErrUnusableSeed
		}
	} else {
		// Ensure the public key parses correctly and is actually on the
		// secp256k1 curve.
		_, err := btcec.ParsePubKey(keyData, btcec.S256())
		if err != nil {
			return nil, err
		}
	}

	return newExtendedKey(version, keyData, chainCode, parentFP, depth,
		childNum, isPrivate), nil
}

func TestPrivKeys(t *testing.T) {
	for _, test := range privKeyTests {
		x, y := btcec.S256().ScalarBaseMult(test.key)
		pub := (*btcec.PublicKey)(&ecdsa.PublicKey{
			Curve: btcec.S256(),
			X:     x,
			Y:     y,
		})
		_, err := btcec.ParsePubKey(pub.SerializeUncompressed(), btcec.S256())
		if err != nil {
			t.Errorf("%s privkey: %v", test.name, err)
			continue
		}
	}
}

// NewAddressPubKey returns a new AddressPubKey which represents a pay-to-pubkey
// address.  The serializedPubKey parameter must be a valid pubkey and can be
// uncompressed, compressed, or hybrid.  The net parameter must be
// btcwire.MainNet or btcwire.TestNet3.
func NewAddressPubKey(serializedPubKey []byte, net btcwire.BitcoinNet) (*AddressPubKey, error) {
	pubKey, err := btcec.ParsePubKey(serializedPubKey, btcec.S256())
	if err != nil {
		return nil, err
	}

	// Set the format of the pubkey.  This probably should be returned
	// from btcec, but do it here to avoid API churn.  We already know the
	// pubkey is valid since it parsed above, so it's safe to simply examine
	// the leading byte to get the format.
	pkFormat := PKFUncompressed
	switch serializedPubKey[0] {
	case 0x02:
		fallthrough
	case 0x03:
		pkFormat = PKFCompressed

	case 0x06:
		fallthrough
	case 0x07:
		pkFormat = PKFHybrid
	}

	ecPubKey := (*btcec.PublicKey)(pubKey)
	addr := &AddressPubKey{pubKeyFormat: pkFormat, pubKey: ecPubKey, net: net}
	return addr, nil
}

// pubKeyBytes returns bytes for the serialized compressed public key associated
// with this extended key in an efficient manner including memoization as
// necessary.
//
// When the extended key is already a public key, the key is simply returned as
// is since it's already in the correct form.  However, when the extended key is
// a private key, the public key will be calculated and memoized so future
// accesses can simply return the cached result.
func (k *ExtendedKey) pubKeyBytes() []byte {
	// Just return the key if it's already an extended public key.
	if !k.isPrivate {
		return k.key
	}

	// This is a private extended key, so calculate and memoize the public
	// key if needed.
	if len(k.pubKey) == 0 {
		pkx, pky := btcec.S256().ScalarBaseMult(k.key)
		pubKey := btcec.PublicKey{Curve: btcec.S256(), X: pkx, Y: pky}
		k.pubKey = pubKey.SerializeCompressed()
	}

	return k.pubKey
}

// BenchmarkSigVerify benchmarks how long it takes the secp256k1 curve to
// verify signatures.
func BenchmarkSigVerify(b *testing.B) {
	b.StopTimer()
	// Randomly generated keypair.
	// Private key: 9e0699c91ca1e3b7e3c9ba71eb71c89890872be97576010fe593fbf3fd57e66d
	pubKey := ecdsa.PublicKey{
		Curve: btcec.S256(),
		X:     fromHex("d2e670a19c6d753d1a6d8b20bd045df8a08fb162cf508956c31268c6d81ffdab"),
		Y:     fromHex("ab65528eefbb8057aa85d597258a3fbd481a24633bc9b47a9aa045c91371de52"),
	}

	// Double sha256 of []byte{0x01, 0x02, 0x03, 0x04}
	msgHash := fromHex("8de472e2399610baaa7f84840547cd409434e31f5d3bd71e4d947f283874f9c0")
	sigR := fromHex("fef45d2892953aa5bbcdb057b5e98b208f1617a7498af7eb765574e29b5d9c2c")
	sigS := fromHex("d47563f52aac6b04b55de236b7c515eb9311757db01e02cff079c3ca6efb063f")

	if !ecdsa.Verify(&pubKey, msgHash.Bytes(), sigR, sigS) {
		b.Errorf("Signature failed to verify")
		return
	}
	b.StartTimer()

	for i := 0; i < b.N; i++ {
		ecdsa.Verify(&pubKey, msgHash.Bytes(), sigR, sigS)
	}
}

// NewMaster creates a new master node for use in creating a hierarchical
// deterministic key chain.  The seed must be between 128 and 512 bits and
// should be generated by a cryptographically secure random generation source.
//
// NOTE: There is an extremely small chance (< 1 in 2^127) the provided seed
// will derive to an unusable secret key.  The ErrUnusable error will be
// returned if this should occur, so the caller must check for it and generate a
// new seed accordingly.
func NewMaster(seed []byte) (*ExtendedKey, error) {
	// Per [BIP32], the seed must be in range [MinSeedBytes, MaxSeedBytes].
	if len(seed) < MinSeedBytes || len(seed) > MaxSeedBytes {
		return nil, ErrInvalidSeedLen
	}

	// First take the HMAC-SHA512 of the master key and the seed data:
	//   I = HMAC-SHA512(Key = "Bitcoin seed", Data = S)
	hmac512 := hmac.New(sha512.New, masterKey)
	hmac512.Write(seed)
	lr := hmac512.Sum(nil)

	// Split "I" into two 32-byte sequences Il and Ir where:
	//   Il = master secret key
	//   Ir = master chain code
	secretKey := lr[:len(lr)/2]
	chainCode := lr[len(lr)/2:]

	// Ensure the key in usable.
	secretKeyNum := new(big.Int).SetBytes(secretKey)
	if secretKeyNum.Cmp(btcec.S256().N) >= 0 || secretKeyNum.Sign() == 0 {
		return nil, ErrUnusableSeed
	}

	parentFP := []byte{0x00, 0x00, 0x00, 0x00}
	return newExtendedKey(btcnet.MainNetParams.HDPrivateKeyID[:], secretKey,
		chainCode, parentFP, 0, 0, true), nil
}

// BechmarkScalarBaseMult benchmarks the secp256k1 curve ScalarBaseMult
// function.
func BechmarkScalarBaseMult(b *testing.B) {
	k := fromHex("d74bf844b0862475103d96a611cf2d898447e288d34b360bc885cb8ce7c00575")
	curve := btcec.S256()
	for i := 0; i < b.N; i++ {
		curve.ScalarBaseMult(k.Bytes())
	}
}

// This example demonstrates signing a message with a secp256k1 private key that
// is first parsed form raw bytes and serializing the generated signature.
func Example_signMessage() {
	// Decode a hex-encoded private key.
	pkBytes, err := hex.DecodeString("22a47fa09a223f2aa079edf85a7c2d4f87" +
		"20ee63e502ee2869afab7de234b80c")
	if err != nil {
		fmt.Println(err)
		return
	}
	privKey, pubKey := btcec.PrivKeyFromBytes(btcec.S256(), pkBytes)

	// Sign a message using the private key.
	message := "test message"
	messageHash := btcwire.DoubleSha256([]byte(message))
	signature, err := privKey.Sign(messageHash)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Serialize and display the signature.
	//
	// NOTE: This is commented out for the example since the signature
	// produced uses random numbers and therefore will always be different.
	//fmt.Printf("Serialized Signature: %x\n", signature.Serialize())

	// Verify the signature for the message using the public key.
	verified := signature.Verify(messageHash, pubKey)
	fmt.Printf("Signature Verified? %v\n", verified)

	// Output:
	// Signature Verified? true
}

func TestPubKeys(t *testing.T) {
	for _, test := range pubKeyTests {
		pk, err := btcec.ParsePubKey(test.key, btcec.S256())
		if err != nil {
			if test.isValid {
				t.Errorf("%s pubkey failed when shouldn't %v",
					test.name, err)
			}
			continue
		}
		if !test.isValid {
			t.Errorf("%s counted as valid when it should fail",
				test.name)
			continue
		}
		var pkStr []byte
		switch test.format {
		case btcec.TstPubkeyUncompressed:
			pkStr = (*btcec.PublicKey)(pk).SerializeUncompressed()
		case btcec.TstPubkeyCompressed:
			pkStr = (*btcec.PublicKey)(pk).SerializeCompressed()
		case btcec.TstPubkeyHybrid:
			pkStr = (*btcec.PublicKey)(pk).SerializeHybrid()
		}
		if !bytes.Equal(test.key, pkStr) {
			t.Errorf("%s pubkey: serialized keys do not match.",
				test.name)
			spew.Dump(test.key)
			spew.Dump(pkStr)
		}
	}
}

func TestVectors(t *testing.T) {
	sha := sha1.New()

	for i, test := range testVectors {
		pub := ecdsa.PublicKey{
			Curve: btcec.S256(),
			X:     fromHex(test.Qx),
			Y:     fromHex(test.Qy),
		}
		msg, _ := hex.DecodeString(test.msg)
		sha.Reset()
		sha.Write(msg)
		hashed := sha.Sum(nil)
		r := fromHex(test.r)
		s := fromHex(test.s)
		if fuck := ecdsa.Verify(&pub, hashed, r, s); fuck != test.ok {
			//t.Errorf("%d: bad result %v %v", i, pub, hashed)
			t.Errorf("%d: bad result %v instead of %v", i, fuck,
				test.ok)
		}
		if testing.Short() {
			break
		}
	}
}

/*-
- Genrates randomized private key, ounce genrated you can call GetPublicKey to
- retrive the public key.
-*/
func GenRandPrivateKey() string {
	privateKeyStrut, err := ecdsa.GenerateKey(btcec.S256(), rand.Reader)
	if err != nil {
		panic("unable to genrate basic keys")
	}
	return base58CheckEncodeKey(0x80, privateKeyStrut.D.Bytes())
}

func newKey(priv, inc *big.Int, f genFunc) *baseKey {
	pk := big.NewInt(0).Set(priv)
	for ; f(pk); inc.Add(inc, one) {
		pk.SetBytes(Sha512Half(inc.Bytes()))
	}
	privKey, _ := btcec.PrivKeyFromBytes(btcec.S256(), pk.Bytes())
	return &baseKey{*privKey}
}

func addPoints(a []byte, b []byte) []byte {
	ap, err := btcec.ParsePubKey(a, btcec.S256())
	if err != nil {
		panic(err)
	}
	bp, err := btcec.ParsePubKey(b, btcec.S256())
	if err != nil {
		panic(err)
	}
	sumX, sumY := btcec.S256().Add(ap.X, ap.Y, bp.X, bp.Y)
	sum := (*btcec.PublicKey)(&ecdsa.PublicKey{
		Curve: btcec.S256(),
		X:     sumX,
		Y:     sumY,
	})
	return sum.SerializeCompressed()
}

// ECPrivKey converts the extended key to a btcec private key and returns it.
// As you might imagine this is only possible if the extended key is a private
// extended key (as determined by the IsPrivate function).  The ErrNotPrivExtKey
// error will be returned if this function is called on a public extended key.
func (k *ExtendedKey) ECPrivKey() (*btcec.PrivateKey, error) {
	if !k.isPrivate {
		return nil, ErrNotPrivExtKey
	}

	privKey, _ := btcec.PrivKeyFromBytes(btcec.S256(), k.key)
	return privKey, nil
}

func TestPrivKeys(t *testing.T) {
	tests := []struct {
		name string
		key  []byte
	}{
		{
			name: "check curve",
			key: []byte{
				0xea, 0xf0, 0x2c, 0xa3, 0x48, 0xc5, 0x24, 0xe6,
				0x39, 0x26, 0x55, 0xba, 0x4d, 0x29, 0x60, 0x3c,
				0xd1, 0xa7, 0x34, 0x7d, 0x9d, 0x65, 0xcf, 0xe9,
				0x3c, 0xe1, 0xeb, 0xff, 0xdc, 0xa2, 0x26, 0x94,
			},
		},
	}

	for _, test := range tests {
		priv, pub := btcec.PrivKeyFromBytes(btcec.S256(), test.key)

		_, err := btcec.ParsePubKey(
			pub.SerializeUncompressed(), btcec.S256())
		if err != nil {
			t.Errorf("%s privkey: %v", test.name, err)
			continue
		}

		hash := []byte{0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8, 0x9}
		sig, err := priv.Sign(hash)
		if err != nil {
			t.Errorf("%s could not sign: %v", test.name, err)
			continue
		}

		if !sig.Verify(hash, pub) {
			t.Errorf("%s could not verify: %v", test.name, err)
			continue
		}

		serializedKey := priv.Serialize()
		if !bytes.Equal(serializedKey, test.key) {
			t.Errorf("%s unexpected serialized bytes - got: %x, "+
				"want: %x", test.name, serializedKey, test.key)
		}
	}
}