def sec(self, compressed=True):
"""returns the binary version of the SEC format"""
if compressed:
if not self.csec:
serialized = ffi.new("unsigned char [33]")
output_len = ffi.new("size_t *", 33)
if not lib.secp256k1_ec_pubkey_serialize(
GLOBAL_CTX,
serialized,
output_len,
self.c,
lib.SECP256K1_EC_COMPRESSED,
):
raise RuntimeError("libsecp256k1 serialize error")
self.csec = bytes(ffi.buffer(serialized, 33))
return self.csec
else:
if not self.usec:
serialized = ffi.new("unsigned char [65]")
output_len = ffi.new("size_t *", 65)
if not lib.secp256k1_ec_pubkey_serialize(
GLOBAL_CTX,
serialized,
output_len,
self.c,
lib.SECP256K1_EC_UNCOMPRESSED,
):
raise RuntimeError("libsecp256k1 serialize error")
self.usec = bytes(ffi.buffer(serialized, 65))
return self.usec
def der(self):
if not self.der_cache:
der = ffi.new("unsigned char[72]")
der_length = ffi.new("size_t *", 72)
if not lib.secp256k1_ecdsa_signature_serialize_der(
GLOBAL_CTX, der, der_length, self.c):
raise RuntimeError("libsecp256k1 der serialize error")
self.der_cache = bytes(ffi.buffer(der, der_length[0]))
return self.der_cache
def bip340(self):
# returns the binary version of BIP340 pubkey
xonly_key = ffi.new("secp256k1_xonly_pubkey *")
if not lib.secp256k1_xonly_pubkey_from_pubkey(GLOBAL_CTX, xonly_key,
ffi.NULL, self.c):
raise RuntimeError("libsecp256k1 xonly pubkey error")
output32 = ffi.new("unsigned char [32]")
if not lib.secp256k1_xonly_pubkey_serialize(GLOBAL_CTX, output32,
xonly_key):
raise RuntimeError("libsecp256k1 xonly serialize error")
return bytes(ffi.buffer(output32, 32))
def tagged_hash(tag, msg):
result = ffi.new("unsigned char [32]")
tag_length = len(tag)
msg_length = len(msg)
if not lib.secp256k1_tagged_sha256(
GLOBAL_CTX,
result,
tag,
tag_length,
msg,
msg_length,
):
raise RuntimeError("libsecp256k1 tagged hash problem")
return bytes(ffi.buffer(result, 32))
def sign_schnorr(self, msg, aux):
if len(msg) != 32:
raise ValueError("msg needs to be 32 bytes")
if len(aux) != 32:
raise ValueError("aux needs to be 32 bytes")
# per libsecp256k1 documentation, this helps against side-channel attacks
if not lib.secp256k1_context_randomize(
GLOBAL_CTX,
secrets.token_bytes(32),
):
raise RuntimeError("libsecp256k1 context randomization error")
keypair = ffi.new("secp256k1_keypair *")
if not lib.secp256k1_keypair_create(
GLOBAL_CTX, keypair, int_to_big_endian(self.secret, 32)):
raise RuntimeError("libsecp256k1 keypair creation problem")
raw_sig = ffi.new("unsigned char [64]")
if not lib.secp256k1_schnorrsig_sign(GLOBAL_CTX, raw_sig, msg, keypair,
aux):
raise RuntimeError("libsecp256k1 schnorr signing problem")
return SchnorrSignature(bytes(ffi.buffer(raw_sig, 64)))