func Sign(msg []byte, seckey []byte) ([]byte, error) {
nonce := randentropy.GetEntropyCSPRNG(32)
var sig []byte = make([]byte, 65)
var recid C.int
var msg_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&msg[0]))
var sig_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&sig[0]))
var seckey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&seckey[0]))
var noncefp_ptr = &(*C.secp256k1_nonce_function_default)
var ndata_ptr = unsafe.Pointer(&nonce[0])
if C.secp256k1_ec_seckey_verify(seckey_ptr) != C.int(1) {
return nil, errors.New("Invalid secret key")
}
ret := C.secp256k1_ecdsa_sign_compact(
msg_ptr,
sig_ptr,
seckey_ptr,
noncefp_ptr,
ndata_ptr,
&recid)
sig[64] = byte(int(recid))
if ret != C.int(1) {
// nonce invalid, retry
return Sign(msg, seckey)
}
return sig, nil
}
func GenerateKeyPair() ([]byte, []byte) {
pubkey_len := C.int(65)
const seckey_len = 32
var pubkey []byte = make([]byte, pubkey_len)
var seckey []byte = randentropy.GetEntropyCSPRNG(seckey_len)
var pubkey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&pubkey[0]))
var seckey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&seckey[0]))
ret := C.secp256k1_ec_pubkey_create(
pubkey_ptr, &pubkey_len,
seckey_ptr, 0) // uncompressed
// or, see randFieldElement at https://golang.org/src/crypto/ecdsa/ecdsa.go#61
// apparently not *every* 256 bit int is on the curve
// XXX: is this the same as validating the privkey before calling create?
if ret != C.int(1) {
return GenerateKeyPair() //invalid secret, try again
}
return pubkey, seckey
}