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Editing: BLAKE2s.py
# =================================================================== # # Copyright (c) 2014, Legrandin <helderijs@gmail.com> # All rights reserved. # # Redistribution and use in source and binary forms, with or without # modification, are permitted provided that the following conditions # are met: # # 1. Redistributions of source code must retain the above copyright # notice, this list of conditions and the following disclaimer. # 2. Redistributions in binary form must reproduce the above copyright # notice, this list of conditions and the following disclaimer in # the documentation and/or other materials provided with the # distribution. # # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE # POSSIBILITY OF SUCH DAMAGE. # =================================================================== from binascii import unhexlify from Crypto.Util.py3compat import bord, tobytes from Crypto.Random import get_random_bytes from Crypto.Util._raw_api import (load_pycryptodome_raw_lib, VoidPointer, SmartPointer, create_string_buffer, get_raw_buffer, c_size_t, c_uint8_ptr) _raw_blake2s_lib = load_pycryptodome_raw_lib("Crypto.Hash._BLAKE2s", """ int blake2s_init(void **state, const uint8_t *key, size_t key_size, size_t digest_size); int blake2s_destroy(void *state); int blake2s_update(void *state, const uint8_t *buf, size_t len); int blake2s_digest(const void *state, uint8_t digest[32]); int blake2s_copy(const void *src, void *dst); """) class BLAKE2s_Hash(object): """A BLAKE2s hash object. Do not instantiate directly. Use the :func:`new` function. :ivar oid: ASN.1 Object ID :vartype oid: string :ivar block_size: the size in bytes of the internal message block, input to the compression function :vartype block_size: integer :ivar digest_size: the size in bytes of the resulting hash :vartype digest_size: integer """ # The internal block size of the hash algorithm in bytes. block_size = 32 def __init__(self, data, key, digest_bytes, update_after_digest): # The size of the resulting hash in bytes. self.digest_size = digest_bytes self._update_after_digest = update_after_digest self._digest_done = False # See https://tools.ietf.org/html/rfc7693 if digest_bytes in (16, 20, 28, 32) and not key: self.oid = "1.3.6.1.4.1.1722.12.2.2." + str(digest_bytes) state = VoidPointer() result = _raw_blake2s_lib.blake2s_init(state.address_of(), c_uint8_ptr(key), c_size_t(len(key)), c_size_t(digest_bytes) ) if result: raise ValueError("Error %d while instantiating BLAKE2s" % result) self._state = SmartPointer(state.get(), _raw_blake2s_lib.blake2s_destroy) if data: self.update(data) def update(self, data): """Continue hashing of a message by consuming the next chunk of data. Args: data (byte string/byte array/memoryview): The next chunk of the message being hashed. """ if self._digest_done and not self._update_after_digest: raise TypeError("You can only call 'digest' or 'hexdigest' on this object") result = _raw_blake2s_lib.blake2s_update(self._state.get(), c_uint8_ptr(data), c_size_t(len(data))) if result: raise ValueError("Error %d while hashing BLAKE2s data" % result) return self def digest(self): """Return the **binary** (non-printable) digest of the message that has been hashed so far. :return: The hash digest, computed over the data processed so far. Binary form. :rtype: byte string """ bfr = create_string_buffer(32) result = _raw_blake2s_lib.blake2s_digest(self._state.get(), bfr) if result: raise ValueError("Error %d while creating BLAKE2s digest" % result) self._digest_done = True return get_raw_buffer(bfr)[:self.digest_size] def hexdigest(self): """Return the **printable** digest of the message that has been hashed so far. :return: The hash digest, computed over the data processed so far. Hexadecimal encoded. :rtype: string """ return "".join(["%02x" % bord(x) for x in tuple(self.digest())]) def verify(self, mac_tag): """Verify that a given **binary** MAC (computed by another party) is valid. Args: mac_tag (byte string/byte array/memoryview): the expected MAC of the message. Raises: ValueError: if the MAC does not match. It means that the message has been tampered with or that the MAC key is incorrect. """ secret = get_random_bytes(16) mac1 = new(digest_bits=160, key=secret, data=mac_tag) mac2 = new(digest_bits=160, key=secret, data=self.digest()) if mac1.digest() != mac2.digest(): raise ValueError("MAC check failed") def hexverify(self, hex_mac_tag): """Verify that a given **printable** MAC (computed by another party) is valid. Args: hex_mac_tag (string): the expected MAC of the message, as a hexadecimal string. Raises: ValueError: if the MAC does not match. It means that the message has been tampered with or that the MAC key is incorrect. """ self.verify(unhexlify(tobytes(hex_mac_tag))) def new(self, **kwargs): """Return a new instance of a BLAKE2s hash object. See :func:`new`. """ if "digest_bytes" not in kwargs and "digest_bits" not in kwargs: kwargs["digest_bytes"] = self.digest_size return new(**kwargs) def new(**kwargs): """Create a new hash object. Args: data (byte string/byte array/memoryview): Optional. The very first chunk of the message to hash. It is equivalent to an early call to :meth:`BLAKE2s_Hash.update`. digest_bytes (integer): Optional. The size of the digest, in bytes (1 to 32). Default is 32. digest_bits (integer): Optional and alternative to ``digest_bytes``. The size of the digest, in bits (8 to 256, in steps of 8). Default is 256. key (byte string): Optional. The key to use to compute the MAC (1 to 64 bytes). If not specified, no key will be used. update_after_digest (boolean): Optional. By default, a hash object cannot be updated anymore after the digest is computed. When this flag is ``True``, such check is no longer enforced. Returns: A :class:`BLAKE2s_Hash` hash object """ data = kwargs.pop("data", None) update_after_digest = kwargs.pop("update_after_digest", False) digest_bytes = kwargs.pop("digest_bytes", None) digest_bits = kwargs.pop("digest_bits", None) if None not in (digest_bytes, digest_bits): raise TypeError("Only one digest parameter must be provided") if (None, None) == (digest_bytes, digest_bits): digest_bytes = 32 if digest_bytes is not None: if not (1 <= digest_bytes <= 32): raise ValueError("'digest_bytes' not in range 1..32") else: if not (8 <= digest_bits <= 256) or (digest_bits % 8): raise ValueError("'digest_bits' not in range 8..256, " "with steps of 8") digest_bytes = digest_bits // 8 key = kwargs.pop("key", b"") if len(key) > 32: raise ValueError("BLAKE2s key cannot exceed 32 bytes") if kwargs: raise TypeError("Unknown parameters: " + str(kwargs)) return BLAKE2s_Hash(data, key, digest_bytes, update_after_digest)
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