Current File : //lib/python3/dist-packages/nacl/bindings/crypto_secretbox.py
# Copyright 2013 Donald Stufft and individual contributors
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from nacl import exceptions as exc
from nacl._sodium import ffi, lib
from nacl.exceptions import ensure
crypto_secretbox_KEYBYTES: int = lib.crypto_secretbox_keybytes()
crypto_secretbox_NONCEBYTES: int = lib.crypto_secretbox_noncebytes()
crypto_secretbox_ZEROBYTES: int = lib.crypto_secretbox_zerobytes()
crypto_secretbox_BOXZEROBYTES: int = lib.crypto_secretbox_boxzerobytes()
crypto_secretbox_MACBYTES: int = lib.crypto_secretbox_macbytes()
crypto_secretbox_MESSAGEBYTES_MAX: int = (
lib.crypto_secretbox_messagebytes_max()
)
def crypto_secretbox(message: bytes, nonce: bytes, key: bytes) -> bytes:
"""
Encrypts and returns the message ``message`` with the secret ``key`` and
the nonce ``nonce``.
:param message: bytes
:param nonce: bytes
:param key: bytes
:rtype: bytes
"""
if len(key) != crypto_secretbox_KEYBYTES:
raise exc.ValueError("Invalid key")
if len(nonce) != crypto_secretbox_NONCEBYTES:
raise exc.ValueError("Invalid nonce")
padded = b"\x00" * crypto_secretbox_ZEROBYTES + message
ciphertext = ffi.new("unsigned char[]", len(padded))
res = lib.crypto_secretbox(ciphertext, padded, len(padded), nonce, key)
ensure(res == 0, "Encryption failed", raising=exc.CryptoError)
ciphertext = ffi.buffer(ciphertext, len(padded))
return ciphertext[crypto_secretbox_BOXZEROBYTES:]
def crypto_secretbox_open(
ciphertext: bytes, nonce: bytes, key: bytes
) -> bytes:
"""
Decrypt and returns the encrypted message ``ciphertext`` with the secret
``key`` and the nonce ``nonce``.
:param ciphertext: bytes
:param nonce: bytes
:param key: bytes
:rtype: bytes
"""
if len(key) != crypto_secretbox_KEYBYTES:
raise exc.ValueError("Invalid key")
if len(nonce) != crypto_secretbox_NONCEBYTES:
raise exc.ValueError("Invalid nonce")
padded = b"\x00" * crypto_secretbox_BOXZEROBYTES + ciphertext
plaintext = ffi.new("unsigned char[]", len(padded))
res = lib.crypto_secretbox_open(plaintext, padded, len(padded), nonce, key)
ensure(
res == 0,
"Decryption failed. Ciphertext failed verification",
raising=exc.CryptoError,
)
plaintext = ffi.buffer(plaintext, len(padded))
return plaintext[crypto_secretbox_ZEROBYTES:]
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