def ec_pubkey_tweak_mul(ctx, pubkey, tweak):
'''Tweak a public key by multiplying it by a tweak value.
Args:
ctx (secp256k1_context*): pointer to a context object
initialized for validation (cannot be
NULL)
pubkey (secp2561_pubkey*): pointer to a public key object
tweak (bytes): pointer to a 32-byte tweak
Returns:
(int, secp256k1_pubkey*): (0 if the tweak was out of range
(chance of around 1 in 2^128 for
uniformly random 32-byte arrays, or
equal to zero. 1 otherwise,
pointer to a public key object)
'''
# Validate context
utils.validate_context(ctx)
# Validate public key
utils.validate_public_key(pubkey)
# Validate tweak
utils.validate_tweak_ser(tweak)
return (lib.secp256k1_ec_pubkey_tweak_mul(ctx, pubkey, tweak), pubkey)
def ec_pubkey_tweak_add(ctx, pubkey, tweak):
''' Tweak a public key by adding tweak times the generator to it.
Args:
ctx (secp256k1_context*): pointer to a context object (cannot be
NULL)
pubkey (secp256k1_pubkey*): pointer to a public key object
tweak (bytes): pointer to a 32-byte tweak
Returns:
(int, secp256k1_pubkey*): (0 if the tweak was out of range
(change of around 1 in 2^128 for
uniformly random 32-byte arrays),
or if the resulting public key
would be invalid (only when the
tweak is the complement of the
corresponding private key). 1
otherwise,
a pointer to a secp256k1_pubkey
containing tweaked public key)
'''
# Validate context
utils.validate_context(ctx)
# Validate public key
utils.validate_public_key(pubkey)
# Validate tweak
utils.validate_tweak_ser(tweak)
return (lib.secp256k1_ec_pubkey_tweak_add(ctx, pubkey, tweak), pubkey)
def ec_pubkey_serialize(ctx, pubkey, flags):
'''Serialize a pubkey object into a serialized byte sequence.
Args:
ctx (secp256k1_context*): a secp256k1 context object
pubkey (secp256k1_pubkey*): a pointer to a secp256k1_pubkey
containing an initialized public
key
flags (int): SECP256K1_EC_COMPRESSED if
serialization should be in
compressed format, otherwise
SECP256K1_EC_UNCOMPRESSED
Returns:
(int, ctype 'char[33]', size_t*): (1,
a pointer to a 65-byte (if
compressed==0) or 33-byte (if
compressed==1) byte array to place
the serialized key in,
Pointer to an integer which is
initially set to the size of the
output, and is overwritten with the
written size)
'''
# Validate context
utils.validate_context(ctx)
# Validate public key
utils.validate_public_key(pubkey)
# Validate flags
if flags == lib.SECP256K1_EC_COMPRESSED:
publen = 33
elif flags == lib.SECP256K1_EC_UNCOMPRESSED:
publen = 65
else:
raise ValueError('Invalid serialized compression format flag.')
# Pointer to a 33- or 65-byte array to place the serialized key in
output = ffi.new('char[]', publen)
# Pointer to an integer which is initially set to the size of the output,
# and is overwritten with the written size
outputlen = ffi.new('size_t *', publen)
output_length = int(ffi.cast('uint32_t', outputlen[0]))
return (lib.secp256k1_ec_pubkey_serialize(ctx, output, outputlen, pubkey,
flags), output[0:output_length],
outputlen)
def ec_pubkey_negate(ctx, pubkey):
'''Negates a public key in place.
Args:
ctx (secp256k1_context*): a secp256k1 context object
pubkey (secp256k1_pubkey*): pointer to the public key to be negated
(cannot be NULL)
Returns:
(int, secp256k1_pubkey*): (1 always,
pointer to the public key to be negated
(cannot be NULL))
'''
# Validate context
utils.validate_context(ctx)
# Validate public key
utils.validate_public_key(pubkey)
return (lib.secp256k1_ec_pubkey_negate(ctx, pubkey), pubkey)
def ecdsa_verify(ctx, sig, msg32, pubkey):
'''Verify an ECDSA signature.
To avoid accepting malleable signatures, only ECDSA signatures in lower-S
form are accepted.
If you need to accept ECDSA signatures from sources that do not obey this
rule, apply secp256k1_ecdsa_signature_normalize to the signature prior to
validation, but be aware that doing so results in malleable signatures.
For details, see the comments for that function.
Args:
ctx (secp256k1_context*): a secp256k1 context object,
initialized for verification
sig (secp256k1_ecdsa_signature*): the signature being verified
(cannot be NULL)
msg32 (bytes): the 32-byte message hash being
verified (cannot be NULL)
pubkey (secp256k1_pubkey*): pointer to an initialized
public key to verify with
(cannot be NULL)
Returns:
(int): 1: correct signature
0: incorrect or unparseable
signature
'''
# Validate context
utils.validate_context(ctx)
# Validate pubkey
utils.validate_public_key(pubkey)
# Validate sig
utils.validate_signature(sig)
# Validate msg32
utils.validate_msg32_ser(msg32)
return lib.secp256k1_ecdsa_verify(ctx, sig, msg32, pubkey)