本文整理汇总了Python中cryptography.hazmat.primitives.ciphers.modes.ModeWithNonce方法的典型用法代码示例。如果您正苦于以下问题：Python modes.ModeWithNonce方法的具体用法？Python modes.ModeWithNonce怎么用？Python modes.ModeWithNonce使用的例子？那么, 这里精选的方法代码示例或许可以为您提供帮助。您也可以进一步了解该方法所在类cryptography.hazmat.primitives.ciphers.modes的用法示例。
在下文中一共展示了modes.ModeWithNonce方法的1个代码示例，这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞，您的评价将有助于系统推荐出更棒的Python代码示例。
示例1: __init__
# 需要导入模块: from cryptography.hazmat.primitives.ciphers import modes [as 别名]
# 或者: from cryptography.hazmat.primitives.ciphers.modes import ModeWithNonce [as 别名]
def __init__(self, backend, cipher, mode, operation):
self._backend = backend
self._cipher = cipher
self._mode = mode
self._operation = operation
# There is a bug in CommonCrypto where block ciphers do not raise
# kCCAlignmentError when finalizing if you supply non-block aligned
# data. To work around this we need to keep track of the block
# alignment ourselves, but only for alg+mode combos that require
# block alignment. OFB, CFB, and CTR make a block cipher algorithm
# into a stream cipher so we don't need to track them (and thus their
# block size is effectively 1 byte just like OpenSSL/CommonCrypto
# treat RC4 and other stream cipher block sizes).
# This bug has been filed as rdar://15589470
self._bytes_processed = 0
if (isinstance(cipher, ciphers.BlockCipherAlgorithm) and not
isinstance(mode, (OFB, CFB, CFB8, CTR))):
self._byte_block_size = cipher.block_size // 8
else:
self._byte_block_size = 1
registry = self._backend._cipher_registry
try:
cipher_enum, mode_enum = registry[type(cipher), type(mode)]
except KeyError:
raise UnsupportedAlgorithm(
"cipher {0} in {1} mode is not supported "
"by this backend.".format(
cipher.name, mode.name if mode else mode),
_Reasons.UNSUPPORTED_CIPHER
)
ctx = self._backend._ffi.new("CCCryptorRef *")
ctx = self._backend._ffi.gc(ctx, self._backend._release_cipher_ctx)
if isinstance(mode, modes.ModeWithInitializationVector):
iv_nonce = mode.initialization_vector
elif isinstance(mode, modes.ModeWithNonce):
iv_nonce = mode.nonce
else:
iv_nonce = self._backend._ffi.NULL
if isinstance(mode, CTR):
mode_option = self._backend._lib.kCCModeOptionCTR_BE
else:
mode_option = 0
res = self._backend._lib.CCCryptorCreateWithMode(
operation,
mode_enum, cipher_enum,
self._backend._lib.ccNoPadding, iv_nonce,
cipher.key, len(cipher.key),
self._backend._ffi.NULL, 0, 0, mode_option, ctx)
self._backend._check_cipher_response(res)
self._ctx = ctx