def secp256k1_example():
"""Usage example for secp256k1 usermodule"""
# randomize context from time to time
# - it helps against sidechannel attacks
# secp256k1.context_randomize(os.urandom(32))
# some random secret key
secret = hashlib.sha256(b"secret key").digest()
print("Secret key:", hexlify(secret).decode())
# Makes sense to check if secret key is valid.
# It will be ok in most cases, only if secret > N it will be invalid
if not secp256k1.ec_seckey_verify(secret):
raise ValueError("Secret key is invalid")
# computing corresponding pubkey
pubkey = secp256k1.ec_pubkey_create(secret)
# serialize the pubkey in compressed format
sec = secp256k1.ec_pubkey_serialize(pubkey, secp256k1.EC_COMPRESSED)
print("Public key:", hexlify(sec).decode())
# this is how you parse the pubkey
pubkey = secp256k1.ec_pubkey_parse(sec)
# Signature generation:
# hash of the string "hello"
msg = hashlib.sha256(b"hello").digest()
# signing
sig = secp256k1.ecdsa_sign(msg, secret)
# serialization
der = secp256k1.ecdsa_signature_serialize_der(sig)
print("Signature:", hexlify(der).decode())
# verification
if secp256k1.ecdsa_verify(sig, msg, pubkey):
print("Signature is valid")
else:
printf("Invalid signature")
def serialize(self) -> bytes:
return secp256k1.ecdsa_signature_serialize_der(self._sig)
def write_to(self, stream) -> int:
return stream.write(secp256k1.ecdsa_signature_serialize_der(self._sig))