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Output Feedback (CFB) mode.
OfbMode ) _copy_bytes)load_pycryptodome_raw_lib VoidPointercreate_string_bufferget_raw_buffer SmartPointerc_size_t c_uint8_ptris_writeable_buffer)get_random_byteszCrypto.Cipher._raw_ofba
int OFB_start_operation(void *cipher,
const uint8_t iv[],
size_t iv_len,
void **pResult);
int OFB_encrypt(void *ofbState,
const uint8_t *in,
uint8_t *out,
size_t data_len);
int OFB_decrypt(void *ofbState,
const uint8_t *in,
uint8_t *out,
size_t data_len);
int OFB_stop_operation(void *state);
c ( e Zd ZdZd ZddZddZdS )r a *Output FeedBack (OFB)*.
This mode is very similar to CBC, but it
transforms the underlying block cipher into a stream cipher.
The keystream is the iterated block encryption of the
previous ciphertext block.
An Initialization Vector (*IV*) is required.
See `NIST SP800-38A`_ , Section 6.4.
.. _`NIST SP800-38A` : http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf
:undocumented: __init__
c F t | _ t | t | t
t | | j }|rt d|z t | j t j | _ | t | | _
t dd| | _ | j | _ ddg| _ dS )aS Create a new block cipher, configured in OFB mode.
:Parameters:
block_cipher : C pointer
A smart pointer to the low-level block cipher instance.
iv : bytes/bytearray/memoryview
The initialization vector to use for encryption or decryption.
It is as long as the cipher block.
**The IV must be a nonce, to to be reused for any other
message**. It shall be a nonce or a random value.
Reusing the *IV* for encryptions performed with the same key
compromises confidentiality.
z)Error %d while instantiating the OFB modeNencryptdecrypt)r _state raw_ofb_libOFB_start_operationgetr r
len
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block_sizer ivIV_next)self block_cipherr results y/builddir/build/BUILD/imunify360-venv-2.6.2/opt/imunify360/venv/lib64/python3.11/site-packages/Crypto/Cipher/_mode_ofb.py__init__zOfbMode.__init__I s $ "mm 00 1A1A1C1C1>> c.encrypt(a) + c.encrypt(b)
is equivalent to:
>>> c.encrypt(a+b)
This function does not add any padding to the plaintext.
:Parameters:
plaintext : bytes/bytearray/memoryview
The piece of data to encrypt.
It can be of any length.
:Keywords:
output : bytearray/memoryview
The location where the ciphertext must be written to.
If ``None``, the ciphertext is returned.
:Return:
If ``output`` is ``None``, the ciphertext is returned as ``bytes``.
Otherwise, ``None``.
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\ d| j vrt d dg| _ | t t | }n_|}t | st d t | t | k r t dt | z t | j t | t | t t | }|rt d|z |t | S dS )a Decrypt data with the key and the parameters set at initialization.
A cipher object is stateful: once you have decrypted a message
you cannot decrypt (or encrypt) another message with the same
object.
The data to decrypt can be broken up in two or
more pieces and `decrypt` can be called multiple times.
That is, the statement:
>>> c.decrypt(a) + c.decrypt(b)
is equivalent to:
>>> c.decrypt(a+b)
This function does not remove any padding from the plaintext.
:Parameters:
ciphertext : bytes/bytearray/memoryview
The piece of data to decrypt.
It can be of any length.
:Keywords:
output : bytearray/memoryview
The location where the plaintext is written to.
If ``None``, the plaintext is returned.
:Return:
If ``output`` is ``None``, the plaintext is returned as ``bytes``.
Otherwise, ``None``.
r z*decrypt() cannot be called after encrypt()Nr& r' z%Error %d while decrypting in OFB mode)
r r( r r r r r OFB_decryptr r r r
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X VWWW:#f++-- "025i.."A B B B (( ):):)4Z)@)@)4Y)?)?)1#j//)B)BD D O Dv MNN N >!),, ,4r$ )N)__name__
__module__ __qualname____doc__r# r r r$ r" r r 7 sW "., ., .,`; ; ; ;z; ; ; ; ; ;r$ c | | }| dd }| dd }d||fk rt | j }||t d n|}t | | j k rt
d| j z |r t dt | z t || S )a Instantiate a cipher object that performs OFB encryption/decryption.
:Parameters:
factory : module
The underlying block cipher, a module from ``Crypto.Cipher``.
:Keywords:
iv : bytes/bytearray/memoryview
The IV to use for OFB.
IV : bytes/bytearray/memoryview
Alias for ``iv``.
Any other keyword will be passed to the underlying block cipher.
See the relevant documentation for details (at least ``key`` will need
to be present).
r Nr )NNz*You must either use 'iv' or 'IV', not bothz.Incorrect IV length (it must be %d bytes long)z Unknown parameters for OFB: %s) _create_base_cipherpopr
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