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253 lines
8.1 KiB
253 lines
8.1 KiB
"""
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Multilayer Linkable Spontaneous Anonymous Group (MLSAG)
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Optimized versions with incremental hashing.
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See https://eprint.iacr.org/2015/1098.pdf for details.
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Also explained in From Zero to Monero section 3.3 and 5.
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----------
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Please note, that the MLSAG code is written in a generic manner,
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where it is designed for multiple public keys (aka inputs). In another
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words, MLSAG should be used to sign multiple inputs, but that is currently
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not the case of Monero, where the inputs are signed one by one.
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So the public keys matrix has always two rows (one for public keys,
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one for commitments), although the algorithm is designed for `n` rows.
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This has one unfortunate effect where `rows` is always equal to 2 and
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dsRows always to 1, but the algorithm is still written as the numbers
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are arbitrary. That's why there are loops such as `for i in range(dsRows)`
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where it is run only once currently.
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----------
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Also note, that the matrix of public keys is indexed by columns first.
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This is because the code was ported from the official Monero client,
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which is written in C++ and where it does have some memory advantages.
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For ring size = 3 and one input the matrix M will look like this:
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|------------------------|------------------------|------------------------|
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| public key 0 | public key 1 | public key 2 |
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| cmt 0 - pseudo_out cmt | cmt 1 - pseudo_out cmt | cmt 2 - pseudo_out cmt |
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and `sk` is equal to:
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|--------------|-----------------------------------------------------|
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| private key* | input secret key's mask - pseudo_out's mask (alpha) |
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* corresponding to one of the public keys (`index` denotes which one)
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----------
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Mostly ported from official Monero client, but also inspired by Mininero.
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Author: Dusan Klinec, ph4r05, 2018
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"""
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import gc
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from typing import TYPE_CHECKING
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if TYPE_CHECKING:
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from typing import Any, TypeGuard, TypeVar
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from trezor.messages import MoneroRctKeyPublic
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from apps.monero.xmr import crypto
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from .serialize_messages.tx_ct_key import CtKey
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T = TypeVar("T")
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def _list_of_type(lst: list[Any], typ: type[T]) -> TypeGuard[list[T]]: ...
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_HASH_KEY_CLSAG_ROUND = b"CLSAG_round\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
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_HASH_KEY_CLSAG_AGG_0 = b"CLSAG_agg_0\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
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_HASH_KEY_CLSAG_AGG_1 = b"CLSAG_agg_1\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
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def generate_clsag_simple(
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message: bytes,
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pubs: list[MoneroRctKeyPublic],
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in_sk: CtKey,
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a: crypto.Scalar,
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cout: crypto.Point,
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index: int,
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mg_buff: list[bytearray],
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) -> list[bytes]:
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"""
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CLSAG for RctType.Simple
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https://eprint.iacr.org/2019/654.pdf
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Corresponds to proveRctCLSAGSimple in rctSigs.cpp
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:param message: the full message to be signed (actually its hash)
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:param pubs: vector of MoneroRctKey; this forms the ring; point values in encoded form; (dest, mask) = (P, C)
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:param in_sk: CtKey; spending private key with input commitment mask (original); better_name: input_secret_key
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:param a: mask from the pseudo output commitment; better name: pseudo_out_alpha
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:param cout: pseudo output commitment; point, decoded; better name: pseudo_out_c
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:param index: specifies corresponding public key to the `in_sk` in the pubs array
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:param mg_buff: buffer to store the signature to
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"""
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from apps.monero.xmr import crypto
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cols = len(pubs)
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if cols == 0:
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raise ValueError("Empty pubs")
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P = _key_vector(cols)
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C_nonzero = _key_vector(cols)
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p = in_sk.dest
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z = crypto.sc_sub_into(None, in_sk.mask, a)
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for i in range(cols):
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P[i] = pubs[i].dest
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C_nonzero[i] = pubs[i].commitment
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pubs[i] = None # type: ignore
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del pubs
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gc.collect()
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return _generate_clsag(message, P, p, C_nonzero, z, cout, index, mg_buff)
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def _generate_clsag(
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message: bytes,
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P: list[bytes],
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p: crypto.Scalar,
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C_nonzero: list[bytes],
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z: crypto.Scalar,
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Cout: crypto.Point,
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index: int,
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mg_buff: list[bytearray],
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) -> list[bytes]:
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from apps.monero.xmr import crypto, crypto_helpers
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from apps.monero.xmr.serialize import int_serialize
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Point = crypto.Point # local_cache_attribute
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Scalar = crypto.Scalar # local_cache_attribute
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encodepoint_into = crypto.encodepoint_into # local_cache_attribute
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sc_mul_into = crypto.sc_mul_into # local_cache_attribute
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scalarmult_into = crypto.scalarmult_into # local_cache_attribute
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sI = Point() # sig.I
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sD = Point() # sig.D
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sc1 = Scalar() # sig.c1
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a = crypto.random_scalar()
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H = Point()
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D = Point()
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Cout_bf = crypto_helpers.encodepoint(Cout)
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tmp_sc = Scalar()
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tmp = Point()
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tmp_bf = bytearray(32)
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crypto.hash_to_point_into(H, P[index])
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scalarmult_into(sI, H, p) # I = p*H
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scalarmult_into(D, H, z) # D = z*H
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sc_mul_into(tmp_sc, z, crypto_helpers.INV_EIGHT_SC) # 1/8*z
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scalarmult_into(sD, H, tmp_sc) # sig.D = 1/8*z*H
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sD = crypto_helpers.encodepoint(sD)
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hsh_P = crypto_helpers.get_keccak() # domain, I, D, P, C, C_offset
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hsh_C = crypto_helpers.get_keccak() # domain, I, D, P, C, C_offset
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hsh_P.update(_HASH_KEY_CLSAG_AGG_0)
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hsh_C.update(_HASH_KEY_CLSAG_AGG_1)
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def hsh_PC(x):
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nonlocal hsh_P, hsh_C
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hsh_P.update(x)
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hsh_C.update(x)
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for x in P:
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hsh_PC(x)
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for x in C_nonzero:
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hsh_PC(x)
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hsh_PC(encodepoint_into(tmp_bf, sI))
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hsh_PC(sD)
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hsh_PC(Cout_bf)
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mu_P = crypto_helpers.decodeint(hsh_P.digest())
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mu_C = crypto_helpers.decodeint(hsh_C.digest())
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del (hsh_PC, hsh_P, hsh_C)
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c_to_hash = crypto_helpers.get_keccak() # domain, P, C, C_offset, message, aG, aH
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update = c_to_hash.update # local_cache_attribute
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update(_HASH_KEY_CLSAG_ROUND)
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for i in range(len(P)):
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update(P[i])
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for i in range(len(P)):
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update(C_nonzero[i])
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update(Cout_bf)
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update(message)
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chasher = c_to_hash.copy()
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crypto.scalarmult_base_into(tmp, a)
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chasher.update(encodepoint_into(tmp_bf, tmp)) # aG
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scalarmult_into(tmp, H, a)
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chasher.update(encodepoint_into(tmp_bf, tmp)) # aH
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c = crypto_helpers.decodeint(chasher.digest())
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del (chasher, H)
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L = Point()
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R = Point()
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c_p = Scalar()
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c_c = Scalar()
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i = (index + 1) % len(P)
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if i == 0:
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crypto.sc_copy(sc1, c)
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mg_buff.append(int_serialize.dump_uvarint_b(len(P)))
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for _ in range(len(P)):
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mg_buff.append(bytearray(32))
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while i != index:
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crypto.random_scalar(tmp_sc)
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crypto.encodeint_into(mg_buff[i + 1], tmp_sc)
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sc_mul_into(c_p, mu_P, c)
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sc_mul_into(c_c, mu_C, c)
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# L = tmp_sc * G + c_P * P[i] + c_c * C[i]
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crypto.add_keys2_into(L, tmp_sc, c_p, crypto.decodepoint_into(tmp, P[i]))
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crypto.decodepoint_into(tmp, C_nonzero[i]) # C = C_nonzero - Cout
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crypto.point_sub_into(tmp, tmp, Cout)
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scalarmult_into(tmp, tmp, c_c)
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crypto.point_add_into(L, L, tmp)
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# R = tmp_sc * HP + c_p * I + c_c * D
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crypto.hash_to_point_into(tmp, P[i])
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crypto.add_keys3_into(R, tmp_sc, tmp, c_p, sI)
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crypto.point_add_into(R, R, scalarmult_into(tmp, D, c_c))
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chasher = c_to_hash.copy()
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chasher.update(encodepoint_into(tmp_bf, L))
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chasher.update(encodepoint_into(tmp_bf, R))
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crypto.decodeint_into(c, chasher.digest())
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P[i] = None # type: ignore
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C_nonzero[i] = None # type: ignore
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i = (i + 1) % len(P)
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if i == 0:
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crypto.sc_copy(sc1, c)
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if i & 3 == 0:
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gc.collect()
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# Final scalar = a - c * (mu_P * p + mu_c * Z)
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sc_mul_into(tmp_sc, mu_P, p)
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crypto.sc_muladd_into(tmp_sc, mu_C, z, tmp_sc)
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crypto.sc_mulsub_into(tmp_sc, c, tmp_sc, a)
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crypto.encodeint_into(mg_buff[index + 1], tmp_sc)
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if TYPE_CHECKING:
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assert _list_of_type(mg_buff, bytes)
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mg_buff.append(crypto_helpers.encodeint(sc1))
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mg_buff.append(sD)
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return mg_buff
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def _key_vector(rows: int) -> list[Any]:
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return [None] * rows
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