Initial commit

venv/Lib/site-packages/rsa/transform.py

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+#  Copyright 2011 Sybren A. Stüvel <sybren@stuvel.eu>
+#
+#  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
+#
+#      https://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.
+
+"""Data transformation functions.
+
+From bytes to a number, number to bytes, etc.
+"""
+
+import math
+
+
+def bytes2int(raw_bytes: bytes) -> int:
+    r"""Converts a list of bytes or an 8-bit string to an integer.
+
+    When using unicode strings, encode it to some encoding like UTF8 first.
+
+    >>> (((128 * 256) + 64) * 256) + 15
+    8405007
+    >>> bytes2int(b'\x80@\x0f')
+    8405007
+
+    """
+    return int.from_bytes(raw_bytes, "big", signed=False)
+
+
+def int2bytes(number: int, fill_size: int = 0) -> bytes:
+    """
+    Convert an unsigned integer to bytes (big-endian)::
+
+    Does not preserve leading zeros if you don't specify a fill size.
+
+    :param number:
+        Integer value
+    :param fill_size:
+        If the optional fill size is given the length of the resulting
+        byte string is expected to be the fill size and will be padded
+        with prefix zero bytes to satisfy that length.
+    :returns:
+        Raw bytes (base-256 representation).
+    :raises:
+        ``OverflowError`` when fill_size is given and the number takes up more
+        bytes than fit into the block. This requires the ``overflow``
+        argument to this function to be set to ``False`` otherwise, no
+        error will be raised.
+    """
+
+    if number < 0:
+        raise ValueError("Number must be an unsigned integer: %d" % number)
+
+    bytes_required = max(1, math.ceil(number.bit_length() / 8))
+
+    if fill_size > 0:
+        return number.to_bytes(fill_size, "big")
+
+    return number.to_bytes(bytes_required, "big")
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()