U g'@spdZdgZddlmZddlmZmZmZmZm Z m Z m Z m Z ddl mZeddZGdddeZd d Zd S) z 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_byteszCryptodome.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@s,eZdZdZddZd ddZd ddZdS) ra*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__ cCst|_t|t|tt||j}|r>t d|t |jtj |_| t||_ tdd||_|j|_ddg|_dS)aSCreate 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_libZOFB_start_operationgetr r lenZ address_of ValueErrorrZOFB_stop_operationrelease block_sizerivIV_next)selfZ block_cipherrresultr?/tmp/pip-unpacked-wheel-_q8s9isk/Cryptodome/Cipher/_mode_ofb.py__init__Is$    zOfbMode.__init__NcCsd|jkrtddg|_|dkr0tt|}n4|}t|sDtdt|t|krdtdt|t|j t |t |t t|}|rtd||dkrt |SdSdS)aEncrypt data with the key and the parameters set at initialization. A cipher object is stateful: once you have encrypted a message you cannot encrypt (or decrypt) another message using the same object. The data to encrypt can be broken up in two or more pieces and `encrypt` can be called multiple times. That is, the statement: >>> 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``. r z*encrypt() cannot be called after decrypt()N4output must be a bytearray or a writeable memoryview9output must have the same length as the input (%d bytes)z%Error %d while encrypting in OFB mode) r TypeErrorrrr rrZ OFB_encryptrrr r r)r plaintextoutput ciphertextrrrrr ys,!    zOfbMode.encryptcCsd|jkrtddg|_|dkr0tt|}n4|}t|sDtdt|t|krdtdt|t|j t |t |t t|}|rtd||dkrt |SdSdS)aDecrypt 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``. rz*decrypt() cannot be called after encrypt()Nrrz%Error %d while decrypting in OFB mode) rr rrr rrZ OFB_decryptrrr r r)rr#r"r!rrrrrs,!    zOfbMode.decrypt)N)N)__name__ __module__ __qualname____doc__rr rrrrrr7s0 =cKs||}|dd}|dd}d||fkr8t|j}|dk rR|dk rVtdn|}t||jkrrtd|j|rtdt|t||S)aInstantiate a cipher object that performs OFB encryption/decryption. :Parameters: factory : module The underlying block cipher, a module from ``Cryptodome.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). rNr)NNz*You must either use 'iv' or 'IV', not bothz.Incorrect IV length (it must be %d bytes long)zUnknown parameters for OFB: %s) Z_create_base_cipherpopr rr rrstrr)factorykwargsZ cipher_staterrrrr_create_ofb_ciphers       r,N)r'__all__ZCryptodome.Util.py3compatrZCryptodome.Util._raw_apirrrrrr r r ZCryptodome.Randomr robjectrr,rrrrs (  >