on ajoute le module rsa car le client aussi en a besoin

[NK2015_Client_Python_Alpha.git] / rsa_source / rsa / transform.py

diff --git a/rsa_source/rsa/transform.py b/rsa_source/rsa/transform.py
new file mode 100644 (file)
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+++ b/rsa_source/rsa/transform.py
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+# -*- coding: utf-8 -*-
+#
+#  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
+#
+#      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.
+
+'''Data transformation functions.
+
+From bytes to a number, number to bytes, etc.
+'''
+
+import types
+import binascii
+
+from rsa import common
+
+def bytes2int(bytes):
+    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('\x80@\x0f')
+    8405007
+
+    """
+
+    return int(binascii.hexlify(bytes), 16)
+
+def int2bytes(number, block_size=None):
+    r'''Converts a number to a string of bytes.
+
+    @param number: the number to convert
+    @param block_size: the number of bytes to output. If the number encoded to
+        bytes is less than this, the block will be zero-padded. When not given,
+        the returned block is not padded.
+
+    @throws OverflowError when block_size is given and the number takes up more
+        bytes than fit into the block.
+
+
+    >>> int2bytes(123456789)
+    '\x07[\xcd\x15'
+    >>> bytes2int(int2bytes(123456789))
+    123456789
+
+    >>> int2bytes(123456789, 6)
+    '\x00\x00\x07[\xcd\x15'
+    >>> bytes2int(int2bytes(123456789, 128))
+    123456789
+
+    >>> int2bytes(123456789, 3)
+    Traceback (most recent call last):
+    ...
+    OverflowError: Needed 4 bytes for number, but block size is 3
+
+    '''
+
+    # Type checking
+    if type(number) not in (types.LongType, types.IntType):
+        raise TypeError("You must pass an integer for 'number', not %s" %
+            number.__class__)
+
+    if number < 0:
+        raise ValueError('Negative numbers cannot be used: %i' % number)
+
+    # Do some bounds checking
+    if block_size is not None:
+        needed_bytes = common.byte_size(number)
+        if needed_bytes > block_size:
+            raise OverflowError('Needed %i bytes for number, but block size '
+                'is %i' % (needed_bytes, block_size))
+    
+    # Convert the number to bytes.
+    bytes = []
+    while number > 0:
+        bytes.insert(0, chr(number & 0xFF))
+        number >>= 8
+
+    # Pad with zeroes to fill the block
+    if block_size is not None:
+        padding = (block_size - needed_bytes) * '\x00'
+    else:
+        padding = ''
+
+    return padding + ''.join(bytes)
+
+
+if __name__ == '__main__':
+    import doctest
+    doctest.testmod()
+