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Diffstat (limited to 'frozen_deps/Cryptodome/Cipher/Salsa20.py')
| -rw-r--r-- | frozen_deps/Cryptodome/Cipher/Salsa20.py | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/frozen_deps/Cryptodome/Cipher/Salsa20.py b/frozen_deps/Cryptodome/Cipher/Salsa20.py new file mode 100644 index 0000000..79e6701 --- /dev/null +++ b/frozen_deps/Cryptodome/Cipher/Salsa20.py @@ -0,0 +1,167 @@ +# -*- coding: utf-8 -*- +# +# Cipher/Salsa20.py : Salsa20 stream cipher (http://cr.yp.to/snuffle.html) +# +# Contributed by Fabrizio Tarizzo <fabrizio@fabriziotarizzo.org>. +# +# =================================================================== +# The contents of this file are dedicated to the public domain. To +# the extent that dedication to the public domain is not available, +# everyone is granted a worldwide, perpetual, royalty-free, +# non-exclusive license to exercise all rights associated with the +# contents of this file for any purpose whatsoever. +# No rights are reserved. +# +# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, +# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF +# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND +# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS +# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN +# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN +# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE +# SOFTWARE. +# =================================================================== + +from Cryptodome.Util.py3compat import _copy_bytes +from Cryptodome.Util._raw_api import (load_pycryptodome_raw_lib, + create_string_buffer, + get_raw_buffer, VoidPointer, + SmartPointer, c_size_t, + c_uint8_ptr, is_writeable_buffer) + +from Cryptodome.Random import get_random_bytes + +_raw_salsa20_lib = load_pycryptodome_raw_lib("Cryptodome.Cipher._Salsa20", + """ + int Salsa20_stream_init(uint8_t *key, size_t keylen, + uint8_t *nonce, size_t nonce_len, + void **pSalsaState); + int Salsa20_stream_destroy(void *salsaState); + int Salsa20_stream_encrypt(void *salsaState, + const uint8_t in[], + uint8_t out[], size_t len); + """) + + +class Salsa20Cipher: + """Salsa20 cipher object. Do not create it directly. Use :py:func:`new` + instead. + + :var nonce: The nonce with length 8 + :vartype nonce: byte string + """ + + def __init__(self, key, nonce): + """Initialize a Salsa20 cipher object + + See also `new()` at the module level.""" + + if len(key) not in key_size: + raise ValueError("Incorrect key length for Salsa20 (%d bytes)" % len(key)) + + if len(nonce) != 8: + raise ValueError("Incorrect nonce length for Salsa20 (%d bytes)" % + len(nonce)) + + self.nonce = _copy_bytes(None, None, nonce) + + self._state = VoidPointer() + result = _raw_salsa20_lib.Salsa20_stream_init( + c_uint8_ptr(key), + c_size_t(len(key)), + c_uint8_ptr(nonce), + c_size_t(len(nonce)), + self._state.address_of()) + if result: + raise ValueError("Error %d instantiating a Salsa20 cipher") + self._state = SmartPointer(self._state.get(), + _raw_salsa20_lib.Salsa20_stream_destroy) + + self.block_size = 1 + self.key_size = len(key) + + def encrypt(self, plaintext, output=None): + """Encrypt a piece of data. + + Args: + plaintext(bytes/bytearray/memoryview): The data to encrypt, of any size. + Keyword Args: + output(bytes/bytearray/memoryview): The location where the ciphertext + is written to. If ``None``, the ciphertext is returned. + Returns: + If ``output`` is ``None``, the ciphertext is returned as ``bytes``. + Otherwise, ``None``. + """ + + if output is None: + ciphertext = create_string_buffer(len(plaintext)) + else: + ciphertext = output + + if not is_writeable_buffer(output): + raise TypeError("output must be a bytearray or a writeable memoryview") + + if len(plaintext) != len(output): + raise ValueError("output must have the same length as the input" + " (%d bytes)" % len(plaintext)) + + result = _raw_salsa20_lib.Salsa20_stream_encrypt( + self._state.get(), + c_uint8_ptr(plaintext), + c_uint8_ptr(ciphertext), + c_size_t(len(plaintext))) + if result: + raise ValueError("Error %d while encrypting with Salsa20" % result) + + if output is None: + return get_raw_buffer(ciphertext) + else: + return None + + def decrypt(self, ciphertext, output=None): + """Decrypt a piece of data. + + Args: + ciphertext(bytes/bytearray/memoryview): The data to decrypt, of any size. + Keyword Args: + output(bytes/bytearray/memoryview): The location where the plaintext + is written to. If ``None``, the plaintext is returned. + Returns: + If ``output`` is ``None``, the plaintext is returned as ``bytes``. + Otherwise, ``None``. + """ + + try: + return self.encrypt(ciphertext, output=output) + except ValueError as e: + raise ValueError(str(e).replace("enc", "dec")) + + +def new(key, nonce=None): + """Create a new Salsa20 cipher + + :keyword key: The secret key to use. It must be 16 or 32 bytes long. + :type key: bytes/bytearray/memoryview + + :keyword nonce: + A value that must never be reused for any other encryption + done with this key. It must be 8 bytes long. + + If not provided, a random byte string will be generated (you can read + it back via the ``nonce`` attribute of the returned object). + :type nonce: bytes/bytearray/memoryview + + :Return: a :class:`Cryptodome.Cipher.Salsa20.Salsa20Cipher` object + """ + + if nonce is None: + nonce = get_random_bytes(8) + + return Salsa20Cipher(key, nonce) + +# Size of a data block (in bytes) +block_size = 1 + +# Size of a key (in bytes) +key_size = (16, 32) + |