// CreateScriptSig signs a raw transaction with keys.
func (rs *RedeemScript) createScriptSig(rawTransactionHashed []byte, signs [][]byte) ([]byte, error) {
//Verify that it worked.
secp256k1 := btcec.S256()
count := 0
for i, signature := range signs {
if signature == nil {
continue
}
count++
sig, err := btcec.ParseSignature(signature, secp256k1)
if err != nil {
return nil, err
}
valid := sig.Verify(rawTransactionHashed, rs.PublicKeys[i].key)
if !valid {
return nil, fmt.Errorf("number %d of signature is invalid", i)
}
}
if count != rs.M {
return nil, fmt.Errorf("number of signatures %d must be %d", count, rs.M)
}
//redeemScript length. To allow redeemScript > 255 bytes, we use OP_PUSHDATA2 and use two bytes to specify length
var redeemScriptLengthBytes []byte
var requiredPUSHDATA byte
if len(rs.Script) < 255 {
requiredPUSHDATA = opPUSHDATA1 //OP_PUSHDATA1 specifies next *one byte* will be length to be pushed to stack
redeemScriptLengthBytes = []byte{byte(len(rs.Script))}
} else {
requiredPUSHDATA = opPUSHDATA2 //OP_PUSHDATA2 specifies next *two bytes* will be length to be pushed to stack
redeemScriptLengthBytes = make([]byte, 2)
binary.LittleEndian.PutUint16(redeemScriptLengthBytes, uint16(len(rs.Script)))
}
//Create scriptSig
var buffer bytes.Buffer
buffer.WriteByte(op0) //OP_0 for Multisig off-by-one error
for _, signature := range signs {
if signature == nil {
continue
}
buffer.WriteByte(byte(len(signature) + 1)) //PUSH each signature. Add one for hash type byte
buffer.Write(signature) // Signature bytes
buffer.WriteByte(0x1) //hash type
}
buffer.WriteByte(requiredPUSHDATA) //OP_PUSHDATA1 or OP_PUSHDATA2 depending on size of redeemScript
buffer.Write(redeemScriptLengthBytes) //PUSH redeemScript
buffer.Write(rs.Script) //redeemScript
return buffer.Bytes(), nil
}
func TestSignatures(t *testing.T) {
for _, test := range signatureTests {
var err error
if test.der {
_, err = btcec.ParseDERSignature(test.sig, btcec.S256())
} else {
_, err = btcec.ParseSignature(test.sig, btcec.S256())
}
if err != nil {
if test.isValid {
t.Errorf("%s signature failed when shouldn't %v",
test.name, err)
} /* else {
t.Errorf("%s got error %v", test.name, err)
} */
continue
}
if !test.isValid {
t.Errorf("%s counted as valid when it should fail",
test.name)
}
}
}
