// 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 := wire.DoubleSha256([]byte(message))
signature, err := privKey.Sign(messageHash)
if err != nil {
fmt.Println(err)
return
}
// Serialize and display the signature.
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:
// Serialized Signature: 304402201008e236fa8cd0f25df4482dddbb622e8a8b26ef0ba731719458de3ccd93805b022032f8ebe514ba5f672466eba334639282616bb3c2f0ab09998037513d1f9e3d6d
// Signature Verified? true
}
func (a *AddrManager) getTriedBucket(netAddr *wire.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 := wire.DoubleSha256(data1)
hash64 := binary.LittleEndian.Uint64(hash1)
hash64 %= triedBucketsPerGroup
var hashbuf [8]byte
binary.LittleEndian.PutUint64(hashbuf[:], hash64)
data2 := []byte{}
data2 = append(data2, a.key[:]...)
data2 = append(data2, GroupKey(netAddr)...)
data2 = append(data2, hashbuf[:]...)
hash2 := wire.DoubleSha256(data2)
return int(binary.LittleEndian.Uint64(hash2) % triedBucketCount)
}
func (a *AddrManager) getNewBucket(netAddr, srcAddr *wire.NetAddress) int {
// bitcoind:
// doublesha256(key + sourcegroup + int64(doublesha256(key + group + sourcegroup))%bucket_per_source_group) % num_new_buckets
data1 := []byte{}
data1 = append(data1, a.key[:]...)
data1 = append(data1, []byte(GroupKey(netAddr))...)
data1 = append(data1, []byte(GroupKey(srcAddr))...)
hash1 := wire.DoubleSha256(data1)
hash64 := binary.LittleEndian.Uint64(hash1)
hash64 %= newBucketsPerGroup
var hashbuf [8]byte
binary.LittleEndian.PutUint64(hashbuf[:], hash64)
data2 := []byte{}
data2 = append(data2, a.key[:]...)
data2 = append(data2, GroupKey(srcAddr)...)
data2 = append(data2, hashbuf[:]...)
hash2 := wire.DoubleSha256(data2)
return int(binary.LittleEndian.Uint64(hash2) % newBucketCount)
}
// 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 := wire.DoubleSha256([]byte(message))
verified := signature.Verify(messageHash, pubKey)
fmt.Println("Signature Verified?", verified)
// Output:
// Signature Verified? true
}
// calcSignatureHash will, given a script and hash type for the current script
// engine instance, calculate the signature hash to be used for signing and
// verification.
func calcSignatureHash(script []parsedOpcode, hashType SigHashType, tx *wire.MsgTx, idx int) []byte {
// The SigHashSingle signature type signs only the corresponding input
// and output (the output with the same index number as the input).
//
// Since transactions can have more inputs than outputs, this means it
// is improper to use SigHashSingle on input indices that don't have a
// corresponding output.
//
// A bug in the original Satoshi client implementation means specifying
// an index that is out of range results in a signature hash of 1 (as a
// uint256 little endian). The original intent appeared to be to
// indicate failure, but unfortunately, it was never checked and thus is
// treated as the actual signature hash. This buggy behavior is now
// part of the consensus and a hard fork would be required to fix it.
//
// Due to this, care must be taken by software that creates transactions
// which make use of SigHashSingle because it can lead to an extremely
// dangerous situation where the invalid inputs will end up signing a
// hash of 1. This in turn presents an opportunity for attackers to
// cleverly construct transactions which can steal those coins provided
// they can reuse signatures.
if hashType&sigHashMask == SigHashSingle && idx >= len(tx.TxOut) {
var hash wire.ShaHash
hash[0] = 0x01
return hash[:]
}
// Remove all instances of OP_CODESEPARATOR from 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 {
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 = nil
}
}
switch hashType & sigHashMask {
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:
// 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 = nil
}
// Sequence on all other inputs is 0, too.
for i := range txCopy.TxIn {
if i != idx {
txCopy.TxIn[i].Sequence = 0
}
}
default:
// Consensus 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
}
// The final hash is the double sha256 of both the serialized modified
// transaction and the hash type (encoded as a 4-byte little-endian
// value) appended.
var wbuf bytes.Buffer
txCopy.Serialize(&wbuf)
binary.Write(&wbuf, binary.LittleEndian, hashType)
return wire.DoubleSha256(wbuf.Bytes())
}