Create keccak.py

audit/keccak.py

@@ -0,0 +1,174 @@
+# ===================================================================
+#
+# Copyright (c) 2015, 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 Crypto.Util.py3compat import bord
+
+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_keccak_lib = load_pycryptodome_raw_lib("Crypto.Hash._keccak",
+                        """
+                        int keccak_init(void **state,
+                                        size_t capacity_bytes,
+                                        uint8_t padding_byte);
+                        int keccak_destroy(void *state);
+                        int keccak_absorb(void *state,
+                                          const uint8_t *in,
+                                          size_t len);
+                        int keccak_squeeze(const void *state,
+                                           uint8_t *out,
+                                           size_t len);
+                        int keccak_digest(void *state, uint8_t *digest, size_t len);
+                        int keccak_copy(const void *src, void *dst);
+                        """)
+
+class Keccak_Hash(object):
+    """A Keccak hash object.
+    Do not instantiate directly.
+    Use the :func:`new` function.
+
+    :ivar digest_size: the size in bytes of the resulting hash
+    :vartype digest_size: integer
+    """
+
+    def __init__(self, data, 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
+
+        state = VoidPointer()
+        result = _raw_keccak_lib.keccak_init(state.address_of(),
+                                             c_size_t(self.digest_size * 2),
+                                             0x01)
+        if result:
+            raise ValueError("Error %d while instantiating keccak" % result)
+        self._state = SmartPointer(state.get(),
+                                   _raw_keccak_lib.keccak_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_keccak_lib.keccak_absorb(self._state.get(),
+                                               c_uint8_ptr(data),
+                                               c_size_t(len(data)))
+        if result:
+            raise ValueError("Error %d while updating keccak" % 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
+        """
+
+        self._digest_done = True
+        bfr = create_string_buffer(self.digest_size)
+        result = _raw_keccak_lib.keccak_digest(self._state.get(),
+                                               bfr,
+                                               c_size_t(self.digest_size))
+        if result:
+            raise ValueError("Error %d while squeezing keccak" % result)
+
+        return get_raw_buffer(bfr)
+
+    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 self.digest()])
+
+    def new(self, **kwargs):
+        """Create a fresh Keccak hash object."""
+
+        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 (bytes/bytearray/memoryview):
+            The very first chunk of the message to hash.
+            It is equivalent to an early call to :meth:`Keccak_Hash.update`.
+        digest_bytes (integer):
+            The size of the digest, in bytes (28, 32, 48, 64).
+        digest_bits (integer):
+            The size of the digest, in bits (224, 256, 384, 512).
+        update_after_digest (boolean):
+            Whether :meth:`Keccak.digest` can be followed by another
+            :meth:`Keccak.update` (default: ``False``).
+
+    :Return: A :class:`Keccak_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):
+        raise TypeError("Digest size (bits, bytes) not provided")
+    if digest_bytes is not None:
+        if digest_bytes not in (28, 32, 48, 64):
+            raise ValueError("'digest_bytes' must be: 28, 32, 48 or 64")
+    else:
+        if digest_bits not in (224, 256, 384, 512):
+            raise ValueError("'digest_bytes' must be: 224, 256, 384 or 512")
+        digest_bytes = digest_bits // 8
+
+    if kwargs:
+        raise TypeError("Unknown parameters: " + str(kwargs))
+
+    return Keccak_Hash(data, digest_bytes, update_after_digest)