201 lines
6.6 KiB
Python
201 lines
6.6 KiB
Python
# Copyright 2018 Donald Stufft and individual contributors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from typing import Tuple
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from nacl import exceptions as exc
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from nacl._sodium import ffi, lib
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from nacl.exceptions import ensure
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__all__ = [
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"crypto_kx_keypair",
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"crypto_kx_client_session_keys",
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"crypto_kx_server_session_keys",
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"crypto_kx_PUBLIC_KEY_BYTES",
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"crypto_kx_SECRET_KEY_BYTES",
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"crypto_kx_SEED_BYTES",
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"crypto_kx_SESSION_KEY_BYTES",
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]
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"""
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Implementations of client, server key exchange
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"""
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crypto_kx_PUBLIC_KEY_BYTES: int = lib.crypto_kx_publickeybytes()
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crypto_kx_SECRET_KEY_BYTES: int = lib.crypto_kx_secretkeybytes()
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crypto_kx_SEED_BYTES: int = lib.crypto_kx_seedbytes()
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crypto_kx_SESSION_KEY_BYTES: int = lib.crypto_kx_sessionkeybytes()
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def crypto_kx_keypair() -> Tuple[bytes, bytes]:
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"""
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Generate a keypair.
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This is a duplicate crypto_box_keypair, but
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is included for api consistency.
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:return: (public_key, secret_key)
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:rtype: (bytes, bytes)
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"""
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public_key = ffi.new("unsigned char[]", crypto_kx_PUBLIC_KEY_BYTES)
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secret_key = ffi.new("unsigned char[]", crypto_kx_SECRET_KEY_BYTES)
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res = lib.crypto_kx_keypair(public_key, secret_key)
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ensure(res == 0, "Key generation failed.", raising=exc.CryptoError)
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return (
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ffi.buffer(public_key, crypto_kx_PUBLIC_KEY_BYTES)[:],
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ffi.buffer(secret_key, crypto_kx_SECRET_KEY_BYTES)[:],
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)
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def crypto_kx_seed_keypair(seed: bytes) -> Tuple[bytes, bytes]:
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"""
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Generate a keypair with a given seed.
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This is functionally the same as crypto_box_seed_keypair, however
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it uses the blake2b hash primitive instead of sha512.
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It is included mainly for api consistency when using crypto_kx.
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:param seed: random seed
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:type seed: bytes
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:return: (public_key, secret_key)
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:rtype: (bytes, bytes)
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"""
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public_key = ffi.new("unsigned char[]", crypto_kx_PUBLIC_KEY_BYTES)
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secret_key = ffi.new("unsigned char[]", crypto_kx_SECRET_KEY_BYTES)
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ensure(
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isinstance(seed, bytes) and len(seed) == crypto_kx_SEED_BYTES,
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"Seed must be a {} byte long bytes sequence".format(
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crypto_kx_SEED_BYTES
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),
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raising=exc.TypeError,
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)
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res = lib.crypto_kx_seed_keypair(public_key, secret_key, seed)
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ensure(res == 0, "Key generation failed.", raising=exc.CryptoError)
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return (
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ffi.buffer(public_key, crypto_kx_PUBLIC_KEY_BYTES)[:],
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ffi.buffer(secret_key, crypto_kx_SECRET_KEY_BYTES)[:],
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)
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def crypto_kx_client_session_keys(
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client_public_key: bytes,
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client_secret_key: bytes,
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server_public_key: bytes,
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) -> Tuple[bytes, bytes]:
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"""
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Generate session keys for the client.
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:param client_public_key:
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:type client_public_key: bytes
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:param client_secret_key:
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:type client_secret_key: bytes
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:param server_public_key:
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:type server_public_key: bytes
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:return: (rx_key, tx_key)
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:rtype: (bytes, bytes)
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"""
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ensure(
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isinstance(client_public_key, bytes)
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and len(client_public_key) == crypto_kx_PUBLIC_KEY_BYTES,
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"Client public key must be a {} bytes long bytes sequence".format(
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crypto_kx_PUBLIC_KEY_BYTES
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),
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raising=exc.TypeError,
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)
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ensure(
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isinstance(client_secret_key, bytes)
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and len(client_secret_key) == crypto_kx_SECRET_KEY_BYTES,
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"Client secret key must be a {} bytes long bytes sequence".format(
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crypto_kx_PUBLIC_KEY_BYTES
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),
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raising=exc.TypeError,
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)
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ensure(
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isinstance(server_public_key, bytes)
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and len(server_public_key) == crypto_kx_PUBLIC_KEY_BYTES,
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"Server public key must be a {} bytes long bytes sequence".format(
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crypto_kx_PUBLIC_KEY_BYTES
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),
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raising=exc.TypeError,
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)
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rx_key = ffi.new("unsigned char[]", crypto_kx_SESSION_KEY_BYTES)
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tx_key = ffi.new("unsigned char[]", crypto_kx_SESSION_KEY_BYTES)
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res = lib.crypto_kx_client_session_keys(
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rx_key, tx_key, client_public_key, client_secret_key, server_public_key
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)
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ensure(
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res == 0,
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"Client session key generation failed.",
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raising=exc.CryptoError,
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)
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return (
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ffi.buffer(rx_key, crypto_kx_SESSION_KEY_BYTES)[:],
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ffi.buffer(tx_key, crypto_kx_SESSION_KEY_BYTES)[:],
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)
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def crypto_kx_server_session_keys(
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server_public_key: bytes,
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server_secret_key: bytes,
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client_public_key: bytes,
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) -> Tuple[bytes, bytes]:
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"""
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Generate session keys for the server.
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:param server_public_key:
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:type server_public_key: bytes
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:param server_secret_key:
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:type server_secret_key: bytes
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:param client_public_key:
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:type client_public_key: bytes
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:return: (rx_key, tx_key)
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:rtype: (bytes, bytes)
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"""
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ensure(
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isinstance(server_public_key, bytes)
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and len(server_public_key) == crypto_kx_PUBLIC_KEY_BYTES,
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"Server public key must be a {} bytes long bytes sequence".format(
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crypto_kx_PUBLIC_KEY_BYTES
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),
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raising=exc.TypeError,
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)
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ensure(
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isinstance(server_secret_key, bytes)
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and len(server_secret_key) == crypto_kx_SECRET_KEY_BYTES,
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"Server secret key must be a {} bytes long bytes sequence".format(
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crypto_kx_PUBLIC_KEY_BYTES
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),
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raising=exc.TypeError,
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)
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ensure(
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isinstance(client_public_key, bytes)
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and len(client_public_key) == crypto_kx_PUBLIC_KEY_BYTES,
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"Client public key must be a {} bytes long bytes sequence".format(
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crypto_kx_PUBLIC_KEY_BYTES
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),
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raising=exc.TypeError,
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)
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rx_key = ffi.new("unsigned char[]", crypto_kx_SESSION_KEY_BYTES)
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tx_key = ffi.new("unsigned char[]", crypto_kx_SESSION_KEY_BYTES)
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res = lib.crypto_kx_server_session_keys(
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rx_key, tx_key, server_public_key, server_secret_key, client_public_key
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)
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ensure(
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res == 0,
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"Server session key generation failed.",
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raising=exc.CryptoError,
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)
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return (
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ffi.buffer(rx_key, crypto_kx_SESSION_KEY_BYTES)[:],
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ffi.buffer(tx_key, crypto_kx_SESSION_KEY_BYTES)[:],
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)
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