A secp256k1 private key
| 338 | return hmac.new(k, v, 'sha256').digest() |
| 339 | |
| 340 | class ECKey(): |
| 341 | """A secp256k1 private key""" |
| 342 | |
| 343 | def __init__(self): |
| 344 | self.valid = False |
| 345 | |
| 346 | def set(self, secret, compressed): |
| 347 | """Construct a private key object with given 32-byte secret and compressed flag.""" |
| 348 | assert(len(secret) == 32) |
| 349 | secret = int.from_bytes(secret, 'big') |
| 350 | self.valid = (secret > 0 and secret < SECP256K1_ORDER) |
| 351 | if self.valid: |
| 352 | self.secret = secret |
| 353 | self.compressed = compressed |
| 354 | |
| 355 | def generate(self, compressed=True): |
| 356 | """Generate a random private key (compressed or uncompressed).""" |
| 357 | self.set(generate_privkey(), compressed) |
| 358 | |
| 359 | def get_bytes(self): |
| 360 | """Retrieve the 32-byte representation of this key.""" |
| 361 | assert(self.valid) |
| 362 | return self.secret.to_bytes(32, 'big') |
| 363 | |
| 364 | @property |
| 365 | def is_valid(self): |
| 366 | return self.valid |
| 367 | |
| 368 | @property |
| 369 | def is_compressed(self): |
| 370 | return self.compressed |
| 371 | |
| 372 | def get_pubkey(self): |
| 373 | """Compute an ECPubKey object for this secret key.""" |
| 374 | assert(self.valid) |
| 375 | ret = ECPubKey() |
| 376 | p = SECP256K1.mul([(SECP256K1_G, self.secret)]) |
| 377 | ret.p = p |
| 378 | ret.valid = True |
| 379 | ret.compressed = self.compressed |
| 380 | return ret |
| 381 | |
| 382 | def sign_ecdsa(self, msg, low_s=True, rfc6979=False): |
| 383 | """Construct a DER-encoded ECDSA signature with this key. |
| 384 | |
| 385 | See https://en.wikipedia.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm for the |
| 386 | ECDSA signer algorithm.""" |
| 387 | assert(self.valid) |
| 388 | z = int.from_bytes(msg, 'big') |
| 389 | # Note: no RFC6979 by default, but a simple random nonce (some tests rely on distinct transactions for the same operation) |
| 390 | if rfc6979: |
| 391 | k = int.from_bytes(rfc6979_nonce(self.secret.to_bytes(32, 'big') + msg), 'big') |
| 392 | else: |
| 393 | k = random.randrange(1, SECP256K1_ORDER) |
| 394 | R = SECP256K1.affine(SECP256K1.mul([(SECP256K1_G, k)])) |
| 395 | r = R[0] % SECP256K1_ORDER |
| 396 | s = (modinv(k, SECP256K1_ORDER) * (z + self.secret * r)) % SECP256K1_ORDER |
| 397 | if low_s and s > SECP256K1_ORDER_HALF: |
no outgoing calls