added v3

venv/lib/python3.11/site-packages/nacl/bindings/utils.py

@@ -0,0 +1,141 @@
+# Copyright 2013-2017 Donald Stufft and individual contributors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import nacl.exceptions as exc
+from nacl._sodium import ffi, lib
+from nacl.exceptions import ensure
+
+
+def sodium_memcmp(inp1: bytes, inp2: bytes) -> bool:
+    """
+    Compare contents of two memory regions in constant time
+    """
+    ensure(isinstance(inp1, bytes), raising=exc.TypeError)
+    ensure(isinstance(inp2, bytes), raising=exc.TypeError)
+
+    ln = max(len(inp1), len(inp2))
+
+    buf1 = ffi.new("char []", ln)
+    buf2 = ffi.new("char []", ln)
+
+    ffi.memmove(buf1, inp1, len(inp1))
+    ffi.memmove(buf2, inp2, len(inp2))
+
+    eqL = len(inp1) == len(inp2)
+    eqC = lib.sodium_memcmp(buf1, buf2, ln) == 0
+
+    return eqL and eqC
+
+
+def sodium_pad(s: bytes, blocksize: int) -> bytes:
+    """
+    Pad the input bytearray ``s`` to a multiple of ``blocksize``
+    using the ISO/IEC 7816-4 algorithm
+
+    :param s: input bytes string
+    :type s: bytes
+    :param blocksize:
+    :type blocksize: int
+    :return: padded string
+    :rtype: bytes
+    """
+    ensure(isinstance(s, bytes), raising=exc.TypeError)
+    ensure(isinstance(blocksize, int), raising=exc.TypeError)
+    if blocksize <= 0:
+        raise exc.ValueError
+    s_len = len(s)
+    m_len = s_len + blocksize
+    buf = ffi.new("unsigned char []", m_len)
+    p_len = ffi.new("size_t []", 1)
+    ffi.memmove(buf, s, s_len)
+    rc = lib.sodium_pad(p_len, buf, s_len, blocksize, m_len)
+    ensure(rc == 0, "Padding failure", raising=exc.CryptoError)
+    return ffi.buffer(buf, p_len[0])[:]
+
+
+def sodium_unpad(s: bytes, blocksize: int) -> bytes:
+    """
+    Remove ISO/IEC 7816-4 padding from the input byte array ``s``
+
+    :param s: input bytes string
+    :type s: bytes
+    :param blocksize:
+    :type blocksize: int
+    :return: unpadded string
+    :rtype: bytes
+    """
+    ensure(isinstance(s, bytes), raising=exc.TypeError)
+    ensure(isinstance(blocksize, int), raising=exc.TypeError)
+    s_len = len(s)
+    u_len = ffi.new("size_t []", 1)
+    rc = lib.sodium_unpad(u_len, s, s_len, blocksize)
+    if rc != 0:
+        raise exc.CryptoError("Unpadding failure")
+    return s[: u_len[0]]
+
+
+def sodium_increment(inp: bytes) -> bytes:
+    """
+    Increment the value of a byte-sequence interpreted
+    as the little-endian representation of a unsigned big integer.
+
+    :param inp: input bytes buffer
+    :type inp: bytes
+    :return: a byte-sequence representing, as a little-endian
+             unsigned big integer, the value ``to_int(inp)``
+             incremented by one.
+    :rtype: bytes
+
+    """
+    ensure(isinstance(inp, bytes), raising=exc.TypeError)
+
+    ln = len(inp)
+    buf = ffi.new("unsigned char []", ln)
+
+    ffi.memmove(buf, inp, ln)
+
+    lib.sodium_increment(buf, ln)
+
+    return ffi.buffer(buf, ln)[:]
+
+
+def sodium_add(a: bytes, b: bytes) -> bytes:
+    """
+    Given a couple of *same-sized* byte sequences, interpreted as the
+    little-endian representation of two unsigned integers, compute
+    the modular addition of the represented values, in constant time for
+    a given common length of the byte sequences.
+
+    :param a: input bytes buffer
+    :type a: bytes
+    :param b: input bytes buffer
+    :type b: bytes
+    :return: a byte-sequence representing, as a little-endian big integer,
+             the integer value of ``(to_int(a) + to_int(b)) mod 2^(8*len(a))``
+    :rtype: bytes
+    """
+    ensure(isinstance(a, bytes), raising=exc.TypeError)
+    ensure(isinstance(b, bytes), raising=exc.TypeError)
+    ln = len(a)
+    ensure(len(b) == ln, raising=exc.TypeError)
+
+    buf_a = ffi.new("unsigned char []", ln)
+    buf_b = ffi.new("unsigned char []", ln)
+
+    ffi.memmove(buf_a, a, ln)
+    ffi.memmove(buf_b, b, ln)
+
+    lib.sodium_add(buf_a, buf_b, ln)
+
+    return ffi.buffer(buf_a, ln)[:]