FM / rsa

/usr/lib/python2.6/site-packages/rsa

Name	Size	Mode	Actions
asn1.py	1781	0644	edit dl rm
asn1.pyc	1653	0644	edit dl rm
asn1.pyo	1653	0644	edit dl rm
bigfile.py	5185	0644	edit dl rm
bigfile.pyc	4786	0644	edit dl rm
bigfile.pyo	4786	0644	edit dl rm
cli.py	12185	0644	edit dl rm
cli.pyc	13319	0644	edit dl rm
cli.pyo	13319	0644	edit dl rm
common.py	4640	0644	edit dl rm
common.pyc	4235	0644	edit dl rm
common.pyo	4235	0644	edit dl rm
core.py	1656	0644	edit dl rm
core.pyc	1485	0644	edit dl rm
core.pyo	1485	0644	edit dl rm
key.py	22867	0644	edit dl rm
key.pyc	23986	0644	edit dl rm
key.pyo	23986	0644	edit dl rm
parallel.py	2299	0644	edit dl rm
parallel.pyc	2098	0644	edit dl rm
parallel.pyo	2098	0644	edit dl rm
pem.py	3537	0644	edit dl rm
pem.pyc	2843	0644	edit dl rm
pem.pyo	2843	0644	edit dl rm
pkcs1.py	12230	0644	edit dl rm
pkcs1.pyc	11173	0644	edit dl rm
pkcs1.pyo	11126	0644	edit dl rm
prime.py	4560	0644	edit dl rm
prime.pyc	3664	0644	edit dl rm
prime.pyo	3618	0644	edit dl rm
randnum.py	2643	0644	edit dl rm
randnum.pyc	2074	0644	edit dl rm
randnum.pyo	2074	0644	edit dl rm
transform.py	6892	0644	edit dl rm
transform.pyc	5856	0644	edit dl rm
transform.pyo	5856	0644	edit dl rm
util.py	3059	0644	edit dl rm
util.pyc	2520	0644	edit dl rm
util.pyo	2449	0644	edit dl rm
varblock.py	5406	0644	edit dl rm
varblock.pyc	4856	0644	edit dl rm
varblock.pyo	4856	0644	edit dl rm
_compat.py	3890	0644	edit dl rm
_compat.pyc	3655	0644	edit dl rm
_compat.pyo	3655	0644	edit dl rm
_version133.py	11764	0644	edit dl rm
_version133.pyc	13639	0644	edit dl rm
_version133.pyo	13639	0644	edit dl rm
_version200.py	15123	0644	edit dl rm
_version200.pyc	15264	0644	edit dl rm
_version200.pyo	15264	0644	edit dl rm
__init__.py	1476	0644	edit dl rm
__init__.pyc	1112	0644	edit dl rm
__init__.pyo	1112	0644	edit dl rm

Edit: /usr/lib/python2.6/site-packages/rsa/common.py (4640B)

# -*- 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
#
#      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.

"""Common functionality shared by several modules."""

def bit_size(num):
    """
    Number of bits needed to represent a integer excluding any prefix
    0 bits.

As per definition from https://wiki.python.org/moin/BitManipulation and
    to match the behavior of the Python 3 API.

Usage::

>>> bit_size(1023)
        10
        >>> bit_size(1024)
        11
        >>> bit_size(1025)
        11

:param num:
        Integer value. If num is 0, returns 0. Only the absolute value of the
        number is considered. Therefore, signed integers will be abs(num)
        before the number's bit length is determined.
    :returns:
        Returns the number of bits in the integer.
    """
    if num == 0:
        return 0
    if num < 0:
        num = -num

# Make sure this is an int and not a float.
    num & 1

hex_num = "%x" % num
    return ((len(hex_num) - 1) * 4) + {
        '0': 0, '1': 1, '2': 2, '3': 2,
        '4': 3, '5': 3, '6': 3, '7': 3,
        '8': 4, '9': 4, 'a': 4, 'b': 4,
        'c': 4, 'd': 4, 'e': 4, 'f': 4,
    }[hex_num[0]]

def _bit_size(number):
    """
    Returns the number of bits required to hold a specific long number.
    """
    if number < 0:
        raise ValueError('Only nonnegative numbers possible: %s' % number)

if number == 0:
        return 0

# This works, even with very large numbers. When using math.log(number, 2),
    # you'll get rounding errors and it'll fail.
    bits = 0
    while number:
        bits += 1
        number >>= 1

return bits

def byte_size(number):
    """
    Returns the number of bytes required to hold a specific long number.

The number of bytes is rounded up.

Usage::

>>> byte_size(1 << 1023)
        128
        >>> byte_size((1 << 1024) - 1)
        128
        >>> byte_size(1 << 1024)
        129

:param number:
        An unsigned integer
    :returns:
        The number of bytes required to hold a specific long number.
    """
    quanta, mod = divmod(bit_size(number), 8)
    if mod or number == 0:
        quanta += 1
    return quanta
    # return int(math.ceil(bit_size(number) / 8.0))

def extended_gcd(a, b):
    """Returns a tuple (r, i, j) such that r = gcd(a, b) = ia + jb
    """
    # r = gcd(a,b) i = multiplicitive inverse of a mod b
    #      or      j = multiplicitive inverse of b mod a
    # Neg return values for i or j are made positive mod b or a respectively
    # Iterateive Version is faster and uses much less stack space
    x = 0
    y = 1
    lx = 1
    ly = 0
    oa = a  # Remember original a/b to remove
    ob = b  # negative values from return results
    while b != 0:
        q = a // b
        (a, b) = (b, a % b)
        (x, lx) = ((lx - (q * x)), x)
        (y, ly) = ((ly - (q * y)), y)
    if lx < 0:
        lx += ob  # If neg wrap modulo orignal b
    if ly < 0:
        ly += oa  # If neg wrap modulo orignal a
    return a, lx, ly  # Return only positive values

def inverse(x, n):
    """Returns x^-1 (mod n)

>>> inverse(7, 4)
    3
    >>> (inverse(143, 4) * 143) % 4
    1
    """

(divider, inv, _) = extended_gcd(x, n)

if divider != 1:
        raise ValueError("x (%d) and n (%d) are not relatively prime" % (x, n))

return inv

def crt(a_values, modulo_values):
    """Chinese Remainder Theorem.

Calculates x such that x = a[i] (mod m[i]) for each i.

:param a_values: the a-values of the above equation
    :param modulo_values: the m-values of the above equation
    :returns: x such that x = a[i] (mod m[i]) for each i

>>> crt([2, 3], [3, 5])
    8

>>> crt([2, 3, 2], [3, 5, 7])
    23

>>> crt([2, 3, 0], [7, 11, 15])
    135
    """

m = 1
    x = 0

for modulo in modulo_values:
        m *= modulo

for (m_i, a_i) in zip(modulo_values, a_values):
        M_i = m // m_i
        inv = inverse(M_i, m_i)

x = (x + a_i * M_i * inv) % m

return x

if __name__ == '__main__':
    import doctest

doctest.testmod()

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