First check-in

lib/Crypto/Hash/_Poly1305.py

@@ -0,0 +1,132 @@
+# -*- coding: utf-8 -*-
+#
+# Hash/_Poly1305.py - Implements the Poly1305 MAC
+#
+# ===================================================================
+# 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 binascii import unhexlify
+
+from Crypto.Util.py3compat import bord, tobytes
+
+from Crypto.Hash import BLAKE2s
+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_poly1305 = load_pycryptodome_raw_lib("Crypto.Hash._Poly1305",
+                        """
+                        int poly1305_init(void **state,
+                                          const uint8_t *key,
+                                          size_t key_size);
+                        int poly1305_destroy(void *state);
+                        int poly1305_copy(const void *src, void *dst);
+                        int poly1305_update(void *state,
+                                            const uint8_t *in,
+                                            size_t len);
+                        int poly1305_digest(const void *state,
+                                            uint8_t digest[16]);
+                        """)
+
+
+class Poly1305(object):
+
+    def __init__(self, key, data):
+
+        self._mac_tag = None
+
+        state = VoidPointer()
+        result = _raw_poly1305.poly1305_init(state.address_of(),
+                                             c_uint8_ptr(key),
+                                             c_size_t(len(key))
+                                             )
+        if result:
+            raise ValueError("Error %d while instantiating Poly1305" % result)
+        self._state = SmartPointer(state.get(),
+                                   _raw_poly1305.poly1305_destroy)
+        if data:
+            self.update(data)
+
+    def update(self, data):
+        
+        if self._mac_tag:
+            raise TypeError("You can only call 'digest' or 'hexdigest' on this object")
+
+        result = _raw_poly1305.poly1305_update(self._state.get(),
+                                               c_uint8_ptr(data),
+                                               c_size_t(len(data)))
+        if result:
+            raise ValueError("Error %d while hashing Poly1305 data" % result)
+        return self
+
+    def copy(self):
+        raise NotImplementedError()
+
+    def digest(self):
+
+        if self._mac_tag:
+            return self._mac_tag
+        
+        bfr = create_string_buffer(16)
+        result = _raw_poly1305.poly1305_digest(self._state.get(),
+                                               bfr)
+        if result:
+            raise ValueError("Error %d while creating Poly1305 digest" % result)
+
+        self._mac_tag = get_raw_buffer(bfr)
+        return self._mac_tag
+
+    def hexdigest(self):
+
+        return "".join(["%02x" % bord(x)
+                        for x in tuple(self.digest())])
+
+    def verify(self, mac_tag):
+
+        secret = get_random_bytes(16)
+
+        mac1 = BLAKE2s.new(digest_bits=160, key=secret, data=mac_tag)
+        mac2 = BLAKE2s.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):
+
+        self.verify(unhexlify(tobytes(hex_mac_tag)))
+
+
+def new(key, msg):
+    """Create a new Poly1305 MAC object.
+
+    Args:
+        key (byte string/byte array/memoryview):
+            key for the Poly1305 object, 32 bytes.
+        msg (byte string/byte array/memoryview):
+            Optional. The very first chunk of the message to authenticate.
+            It is equivalent to an early call to `_Poly1305.update`. Optional.
+
+    Returns:
+        A :class:`_Poly1305` object
+    """
+
+    return Poly1305(key, msg)