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)
}

// String returns the extended key as a human-readable base58-encoded string.
func (k *ExtendedKey) String() string {
	if len(k.key) == 0 {
		return "zeroed extended key"
	}

	var childNumBytes [4]byte
	depthByte := byte(k.depth % 256)
	binary.BigEndian.PutUint32(childNumBytes[:], k.childNum)

	// The serialized format is:
	//   version (4) || depth (1) || parent fingerprint (4)) ||
	//   child num (4) || chain code (32) || key data (33) || checksum (4)
	serializedBytes := make([]byte, 0, serializedKeyLen+4)
	serializedBytes = append(serializedBytes, k.version...)
	serializedBytes = append(serializedBytes, depthByte)
	serializedBytes = append(serializedBytes, k.parentFP...)
	serializedBytes = append(serializedBytes, childNumBytes[:]...)
	serializedBytes = append(serializedBytes, k.chainCode...)
	if k.isPrivate {
		serializedBytes = append(serializedBytes, 0x00)
		serializedBytes = append(serializedBytes, k.key...)
	} else {
		serializedBytes = append(serializedBytes, k.pubKeyBytes()...)
	}

	checkSum := btcwire.DoubleSha256(serializedBytes)[:4]
	serializedBytes = append(serializedBytes, checkSum...)
	return btcutil.Base58Encode(serializedBytes)
}

// 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
}

// DecodeAddress decodes a human-readable payment address string
// returning the 20-byte decoded address, along with the Bitcoin
// network for the address.
//
// DEPRECATED - Use DecodeAddr to decode a string encoded address to
// the Address interface.
func DecodeAddress(addr string) (addrHash []byte, net btcwire.BitcoinNet, err error) {
	decoded := Base58Decode(addr)

	// Length of decoded address must be 20 bytes + 1 byte for a network
	// identifier byte + 4 bytes of checksum.
	if len(decoded) != ripemd160.Size+5 {
		return nil, 0x00, ErrMalformedAddress
	}

	switch decoded[0] {
	case MainNetAddr:
		net = btcwire.MainNet
	case TestNetAddr:
		net = btcwire.TestNet3
	default:
		return nil, 0, ErrUnknownNet
	}

	// Checksum is first four bytes of double SHA256 of the network byte
	// and addrHash.  Verify this matches the final 4 bytes of the decoded
	// address.
	tosum := decoded[:ripemd160.Size+1]
	cksum := btcwire.DoubleSha256(tosum)[:4]
	if !bytes.Equal(cksum, decoded[len(decoded)-4:]) {
		return nil, net, ErrMalformedAddress
	}

	addrHash = make([]byte, ripemd160.Size, ripemd160.Size)
	copy(addrHash, decoded[1:ripemd160.Size+1])

	return addrHash, net, nil
}

// encodeAddress returns a human-readable payment address given a ripemd160 hash
// and netID which encodes the bitcoin network and address type.  It is used
// in both pay-to-pubkey-hash (P2PKH) and pay-to-script-hash (P2SH) address
// encoding.
func encodeAddress(hash160 []byte, netID byte) string {
	// Format is 1 byte for a network and address class (i.e. P2PKH vs
	// P2SH), 20 bytes for a RIPEMD160 hash, and 4 bytes of checksum.
	b := make([]byte, 0, 1+ripemd160.Size+4)
	b = append(b, netID)
	b = append(b, hash160...)
	cksum := btcwire.DoubleSha256(b)[:4]
	b = append(b, cksum...)
	return Base58Encode(b)
}

func (a *AddrManager) getTriedBucket(netAddr *btcwire.NetAddress) int {
	// bitcoind hashes this as:
	// doublesha256(key + group + truncate_to_64bits(doublesha256(key)) % buckets_per_group) % num_buckets
	data1 := []byte{}
	data1 = append(data1, a.key[:]...)
	data1 = append(data1, []byte(NetAddressKey(netAddr))...)
	hash1 := btcwire.DoubleSha256(data1)
	hash64 := binary.LittleEndian.Uint64(hash1)
	hash64 %= triedBucketsPerGroup
	hashbuf := new(bytes.Buffer)
	binary.Write(hashbuf, binary.LittleEndian, hash64)
	data2 := []byte{}
	data2 = append(data2, a.key[:]...)
	data2 = append(data2, GroupKey(netAddr)...)
	data2 = append(data2, hashbuf.Bytes()...)

	hash2 := btcwire.DoubleSha256(data2)
	return int(binary.LittleEndian.Uint64(hash2) % triedBucketCount)
}

// hashMerkleBranches takes two hashes, treated as the left and right tree
// nodes, and returns the hash of their concatenation.  This is a helper
// function used to during generatation of a merkle tree.
func hashMerkleBranches(left *btcwire.ShaHash, right *btcwire.ShaHash) *btcwire.ShaHash {
	// Concatenate the left and right nodes.
	var sha [btcwire.HashSize * 2]byte
	copy(sha[:btcwire.HashSize], left.Bytes())
	copy(sha[btcwire.HashSize:], right.Bytes())

	// Create a new sha hash from the double sha 256.  Ignore the error
	// here since SetBytes can't fail here due to the fact DoubleSha256
	// always returns a []byte of the right size regardless of input.
	newSha, _ := btcwire.NewShaHash(btcwire.DoubleSha256(sha[:]))
	return newSha
}

func (a *AddrManager) getNewBucket(netAddr, srcAddr *btcwire.NetAddress) int {
	// bitcoind:
	// doublesha256(key + sourcegroup + int64(doublesha256(key + group + sourcegroup))%bucket_per_source_group) % num_new_buckes

	data1 := []byte{}
	data1 = append(data1, a.key[:]...)
	data1 = append(data1, []byte(GroupKey(netAddr))...)
	data1 = append(data1, []byte(GroupKey(srcAddr))...)
	hash1 := btcwire.DoubleSha256(data1)
	hash64 := binary.LittleEndian.Uint64(hash1)
	hash64 %= newBucketsPerGroup
	hashbuf := new(bytes.Buffer)
	binary.Write(hashbuf, binary.LittleEndian, hash64)
	data2 := []byte{}
	data2 = append(data2, a.key[:]...)
	data2 = append(data2, GroupKey(srcAddr)...)
	data2 = append(data2, hashbuf.Bytes()...)

	hash2 := btcwire.DoubleSha256(data2)
	return int(binary.LittleEndian.Uint64(hash2) % newBucketCount)
}

func encodeHashWithNetId(netID byte, addrHash []byte) (encoded string, err error) {
	tosum := append([]byte{netID}, addrHash...)
	cksum := btcwire.DoubleSha256(tosum)

	// Address before base58 encoding is 1 byte for netID, 20 bytes for
	// hash, plus 4 bytes of checksum.
	a := make([]byte, 25, 25)
	a[0] = netID
	copy(a[1:], addrHash)
	copy(a[21:], cksum[:4])

	return Base58Encode(a), nil
}

// 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
}

// DecodeAddr decodes the string encoding of an address and returns
// the Address if addr is a valid encoding for a known address type.
//
// This is named DecodeAddr and not DecodeAddress due to DecodeAddress
// already being defined for an old api.  When the old api is eventually
// removed, a proper DecodeAddress function will be added, and DecodeAddr
// will become deprecated.
func DecodeAddr(addr string) (Address, error) {
	decoded := Base58Decode(addr)

	// Switch on decoded length to determine the type.
	switch len(decoded) {
	case 1 + ripemd160.Size + 4: // P2PKH or P2SH
		// Parse the network and hash type (pubkey hash vs script
		// hash) from the first byte.
		net := btcwire.MainNet
		isscript := false
		switch decoded[0] {
		case MainNetAddr:
			// Use defaults.

		case TestNetAddr:
			net = btcwire.TestNet3

		case MainNetScriptHash:
			isscript = true

		case TestNetScriptHash:
			isscript = true
			net = btcwire.TestNet3

		default:
			return nil, ErrUnknownIdentifier
		}

		// Verify hash checksum.  Checksum is calculated as the first
		// four bytes of double SHA256 of the network byte and hash.
		tosum := decoded[:ripemd160.Size+1]
		cksum := btcwire.DoubleSha256(tosum)[:4]
		if !bytes.Equal(cksum, decoded[len(decoded)-4:]) {
			return nil, ErrChecksumMismatch
		}

		// Return concrete type.
		if isscript {
			return NewAddressScriptHashFromHash(
				decoded[1:ripemd160.Size+1], net)
		}
		return NewAddressPubKeyHash(decoded[1:ripemd160.Size+1],
			net)

	default:
		return nil, errors.New("decoded address is of unknown size")
	}
}

// encodeAddress returns a human-readable payment address given a ripemd160 hash
// and netid which encodes the bitcoin network and address type.  It is used
// in both pay-to-pubkey-hash (P2PKH) and pay-to-script-hash (P2SH) address
// encoding.
func encodeAddress(hash160 []byte, netID byte) string {
	tosum := make([]byte, ripemd160.Size+1)
	tosum[0] = netID
	copy(tosum[1:], hash160)
	cksum := btcwire.DoubleSha256(tosum)

	// Address before base58 encoding is 1 byte for netID, ripemd160 hash
	// size, plus 4 bytes of checksum (total 25).
	b := make([]byte, ripemd160.Size+5, ripemd160.Size+5)
	b[0] = netID
	copy(b[1:], hash160)
	copy(b[ripemd160.Size+1:], cksum[:4])

	return Base58Encode(b)

}

// DecodePrivateKey takes a Wallet Import Format (WIF) string and
// decodes into a 32-byte private key.
func DecodePrivateKey(wif string) ([]byte, btcwire.BitcoinNet, bool, error) {
	decoded := Base58Decode(wif)
	decodedLen := len(decoded)
	compressed := false

	// Length of decoded privkey must be 32 bytes + an optional 1 byte (0x01)
	// if compressed, plus 1 byte for netID + 4 bytes of checksum
	if decodedLen == 32+6 {
		compressed = true
		if decoded[33] != 0x01 {
			return nil, 0, compressed, ErrMalformedPrivateKey
		}
	} else if decodedLen != 32+5 {
		return nil, 0, compressed, ErrMalformedPrivateKey
	}

	var net btcwire.BitcoinNet
	switch decoded[0] {
	case MainNetKey:
		net = btcwire.MainNet
	case TestNetKey:
		net = btcwire.TestNet3
	default:
		return nil, 0, compressed, ErrUnknownNet
	}

	// Checksum is first four bytes of double SHA256 of the identifier byte
	// and privKey.  Verify this matches the final 4 bytes of the decoded
	// private key.
	var tosum []byte
	if compressed {
		tosum = decoded[:32+1+1]
	} else {
		tosum = decoded[:32+1]
	}
	cksum := btcwire.DoubleSha256(tosum)[:4]
	if !bytes.Equal(cksum, decoded[decodedLen-4:]) {
		return nil, 0, compressed, ErrMalformedPrivateKey
	}

	privKey := make([]byte, 32, 32)
	copy(privKey[:], decoded[1:32+1])

	return privKey, net, compressed, nil
}

// DecodeAddress decodes the string encoding of an address and returns
// the Address if addr is a valid encoding for a known address type.
//
// The bitcoin network the address is associated with is extracted if possible.
// When the address does not encode the network, such as in the case of a raw
// public key, the address will be associated with the passed defaultNet.
func DecodeAddress(addr string, defaultNet *btcnet.Params) (Address, error) {
	// Serialized public keys are either 65 bytes (130 hex chars) if
	// uncompressed/hybrid or 33 bytes (66 hex chars) if compressed.
	if len(addr) == 130 || len(addr) == 66 {
		serializedPubKey, err := hex.DecodeString(addr)
		if err != nil {
			return nil, err
		}
		return NewAddressPubKey(serializedPubKey, defaultNet)
	}

	// Switch on decoded length to determine the type.
	decoded := Base58Decode(addr)
	switch len(decoded) {
	case 1 + ripemd160.Size + 4: // P2PKH or P2SH
		// Verify hash checksum.  Checksum is calculated as the first
		// four bytes of double SHA256 of the network byte and hash.
		tosum := decoded[:ripemd160.Size+1]
		cksum := btcwire.DoubleSha256(tosum)[:4]
		if !bytes.Equal(cksum, decoded[len(decoded)-4:]) {
			return nil, ErrChecksumMismatch
		}

		netID := decoded[0]
		isP2PKH := btcnet.IsPubKeyHashAddrID(netID)
		isP2SH := btcnet.IsScriptHashAddrID(netID)
		switch hash160 := decoded[1 : ripemd160.Size+1]; {
		case isP2PKH && isP2SH:
			return nil, ErrAddressCollision
		case isP2PKH:
			return newAddressPubKeyHash(hash160, netID)
		case isP2SH:
			return newAddressScriptHashFromHash(hash160, netID)
		default:
			return nil, ErrUnknownAddressType
		}

	default:
		return nil, errors.New("decoded address is of unknown size")
	}
}

// String creates the Wallet Import Format string encoding of a WIF structure.
// See DecodeWIF for a detailed breakdown of the format and requirements of
// a valid WIF string.
func (w *WIF) String() string {
	// Precalculate size.  Maximum number of bytes before base58 encoding
	// is one byte for the network, 32 bytes of private key, possibly one
	// extra byte if the pubkey is to be compressed, and finally four
	// bytes of checksum.
	encodeLen := 1 + btcec.PrivKeyBytesLen + 4
	if w.CompressPubKey {
		encodeLen++
	}

	a := make([]byte, 0, encodeLen)
	a = append(a, w.netID)
	// Pad and append bytes manually, instead of using Serialize, to
	// avoid another call to make.
	a = paddedAppend(btcec.PrivKeyBytesLen, a, w.PrivKey.D.Bytes())
	if w.CompressPubKey {
		a = append(a, compressMagic)
	}
	cksum := btcwire.DoubleSha256(a)[:4]
	a = append(a, cksum...)
	return Base58Encode(a)
}

// EncodePrivateKey takes a 32-byte private key and encodes it into the
// Wallet Import Format (WIF).
func EncodePrivateKey(privKey []byte, net btcwire.BitcoinNet, compressed bool) (string, error) {
	if len(privKey) != 32 {
		return "", ErrMalformedPrivateKey
	}

	var netID byte
	switch net {
	case btcwire.MainNet:
		netID = MainNetKey
	case btcwire.TestNet3:
		netID = TestNetKey
	default:
		return "", ErrUnknownNet
	}

	tosum := append([]byte{netID}, privKey...)
	if compressed {
		tosum = append(tosum, 0x01)
	}
	cksum := btcwire.DoubleSha256(tosum)

	// Private key before base58 encoding is 1 byte for netID, 32 bytes for
	// privKey, plus an optional byte (0x01) if copressed, plus 4 bytes of checksum.
	encodeLen := 37
	if compressed {
		encodeLen += 1
	}
	a := make([]byte, encodeLen, encodeLen)
	a[0] = netID
	copy(a[1:], privKey)
	if compressed {
		copy(a[32+1:], []byte{0x01})
		copy(a[32+1+1:], cksum[:4])
	} else {
		copy(a[32+1:], cksum[:4])
	}
	return Base58Encode(a), nil
}

// DecodeWIF creates a new WIF structure by decoding the string encoding of
// the import format.
//
// The WIF string must be a base58-encoded string of the following byte
// sequence:
//
//  * 1 byte to identify the network, must be 0x80 for mainnet or 0xef for
//    either testnet3 or the regression test network
//  * 32 bytes of a binary-encoded, big-endian, zero-padded private key
//  * Optional 1 byte (equal to 0x01) if the address being imported or exported
//    was created by taking the RIPEMD160 after SHA256 hash of a serialized
//    compressed (33-byte) public key
//  * 4 bytes of checksum, must equal the first four bytes of the double SHA256
//    of every byte before the checksum in this sequence
//
// If the base58-decoded byte sequence does not match this, DecodeWIF will
// return a non-nil error.  ErrMalformedPrivateKey is returned when the WIF
// is of an impossible length or the expected compressed pubkey magic number
// does not equal the expected value of 0x01.  ErrChecksumMismatch is returned
// if the expected WIF checksum does not match the calculated checksum.
func DecodeWIF(wif string) (*WIF, error) {
	decoded := Base58Decode(wif)
	decodedLen := len(decoded)
	var compress bool

	// Length of base58 decoded WIF must be 32 bytes + an optional 1 byte
	// (0x01) if compressed, plus 1 byte for netID + 4 bytes of checksum.
	switch decodedLen {
	case 1 + btcec.PrivKeyBytesLen + 1 + 4:
		if decoded[33] != compressMagic {
			return nil, ErrMalformedPrivateKey
		}
		compress = true
	case 1 + btcec.PrivKeyBytesLen + 4:
		compress = false
	default:
		return nil, ErrMalformedPrivateKey
	}

	// Checksum is first four bytes of double SHA256 of the identifier byte
	// and privKey.  Verify this matches the final 4 bytes of the decoded
	// private key.
	var tosum []byte
	if compress {
		tosum = decoded[:1+btcec.PrivKeyBytesLen+1]
	} else {
		tosum = decoded[:1+btcec.PrivKeyBytesLen]
	}
	cksum := btcwire.DoubleSha256(tosum)[:4]
	if !bytes.Equal(cksum, decoded[decodedLen-4:]) {
		return nil, ErrChecksumMismatch
	}

	netID := decoded[0]
	privKeyBytes := decoded[1 : 1+btcec.PrivKeyBytesLen]
	privKey, _ := btcec.PrivKeyFromBytes(btcec.S256(), privKeyBytes)
	return &WIF{privKey, compress, netID}, nil
}

// This example demonstrates verifying a secp256k1 signature against a public
// key that is first parsed from raw bytes.  The signature is also parsed from
// raw bytes.
func Example_verifySignature() {
	// Decode hex-encoded serialized public key.
	pubKeyBytes, err := hex.DecodeString("02a673638cb9587cb68ea08dbef685c" +
		"6f2d2a751a8b3c6f2a7e9a4999e6e4bfaf5")
	if err != nil {
		fmt.Println(err)
		return
	}
	pubKey, err := btcec.ParsePubKey(pubKeyBytes, btcec.S256())
	if err != nil {
		fmt.Println(err)
		return
	}

	// Decode hex-encoded serialized signature.
	sigBytes, err := hex.DecodeString("30450220090ebfb3690a0ff115bb1b38b" +
		"8b323a667b7653454f1bccb06d4bbdca42c2079022100ec95778b51e707" +
		"1cb1205f8bde9af6592fc978b0452dafe599481c46d6b2e479")
	if err != nil {
		fmt.Println(err)
		return
	}
	signature, err := btcec.ParseSignature(sigBytes, btcec.S256())
	if err != nil {
		fmt.Println(err)
		return
	}

	// Verify the signature for the message using the public key.
	message := "test message"
	messageHash := btcwire.DoubleSha256([]byte(message))
	verified := signature.Verify(messageHash, pubKey)
	fmt.Println("Signature Verified?", verified)

	// Output:
	// Signature Verified? true
}

// calcScriptHash will, given the a script and hashtype for the current
// scriptmachine, calculate the doubleSha256 hash of the transaction and
// script to be used for signature signing and verification.
func calcScriptHash(script []parsedOpcode, hashType byte, tx *btcwire.MsgTx, idx int) []byte {

	// remove all instances of OP_CODESEPARATOR still left in the script
	script = removeOpcode(script, OP_CODESEPARATOR)

	// Make a deep copy of the transaction, zeroing out the script
	// for all inputs that are not currently being processed.
	txCopy := tx.Copy()
	for i := range txCopy.TxIn {
		var txIn btcwire.TxIn
		txIn = *txCopy.TxIn[i]
		txCopy.TxIn[i] = &txIn
		if i == idx {
			// unparseScript cannot fail here, because removeOpcode
			// above only returns a valid script.
			sigscript, _ := unparseScript(script)
			txCopy.TxIn[idx].SignatureScript = sigscript
		} else {
			txCopy.TxIn[i].SignatureScript = []byte{}
		}
	}
	// Default behaviour has all outputs set up.
	for i := range txCopy.TxOut {
		var txOut btcwire.TxOut
		txOut = *txCopy.TxOut[i]
		txCopy.TxOut[i] = &txOut
	}

	switch hashType & 31 {
	case SigHashNone:
		txCopy.TxOut = txCopy.TxOut[0:0] // empty slice
		for i := range txCopy.TxIn {
			if i != idx {
				txCopy.TxIn[i].Sequence = 0
			}
		}
	case SigHashSingle:
		if idx >= len(txCopy.TxOut) {
			// This was created by a buggy implementation.
			// In this case we do the same as bitcoind and bitcoinj
			// and return 1 (as a uint256 little endian) as an
			// error. Unfortunately this was not checked anywhere
			// and thus is treated as the actual
			// hash.
			hash := make([]byte, 32)
			hash[0] = 0x01
			return hash
		}
		// Resize output array to up to and including requested index.
		txCopy.TxOut = txCopy.TxOut[:idx+1]
		// all but  current output get zeroed out
		for i := 0; i < idx; i++ {
			txCopy.TxOut[i].Value = -1
			txCopy.TxOut[i].PkScript = []byte{}
		}
		// Sequence on all other inputs is 0, too.
		for i := range txCopy.TxIn {
			if i != idx {
				txCopy.TxIn[i].Sequence = 0
			}
		}
	default:
		// XXX bitcoind treats undefined hashtypes like normal
		// SigHashAll for purposes of hash generation.
		fallthrough
	case SigHashOld:
		fallthrough
	case SigHashAll:
		// nothing special here
	}
	if hashType&SigHashAnyOneCanPay != 0 {
		txCopy.TxIn = txCopy.TxIn[idx : idx+1]
		idx = 0
	}

	var wbuf bytes.Buffer
	txCopy.Serialize(&wbuf)
	// Append LE 4 bytes hash type
	binary.Write(&wbuf, binary.LittleEndian, uint32(hashType))

	return btcwire.DoubleSha256(wbuf.Bytes())
}

func dsha256(data []byte) []byte {
	return btcwire.DoubleSha256(data)
}