186 lines
5.7 KiB
Python
186 lines
5.7 KiB
Python
#
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# SelfTest/Protocol/test_secret_sharing.py: Self-test for secret sharing protocols
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#
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# ===================================================================
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#
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# Copyright (c) 2014, Legrandin <helderijs@gmail.com>
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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#
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# 1. Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in
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# the documentation and/or other materials provided with the
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# distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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# COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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# ===================================================================
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from unittest import main, TestCase, TestSuite
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from binascii import unhexlify, hexlify
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from Crypto.Util.py3compat import *
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from Crypto.SelfTest.st_common import list_test_cases
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from Crypto.Protocol.SecretSharing import Shamir, _Element, \
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_mult_gf2, _div_gf2
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class GF2_Tests(TestCase):
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def test_mult_gf2(self):
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# Prove mult by zero
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x = _mult_gf2(0,0)
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self.assertEqual(x, 0)
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# Prove mult by unity
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x = _mult_gf2(34, 1)
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self.assertEqual(x, 34)
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z = 3 # (x+1)
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y = _mult_gf2(z, z)
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self.assertEqual(y, 5) # (x+1)^2 = x^2 + 1
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y = _mult_gf2(y, z)
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self.assertEqual(y, 15) # (x+1)^3 = x^3 + x^2 + x + 1
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y = _mult_gf2(y, z)
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self.assertEqual(y, 17) # (x+1)^4 = x^4 + 1
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# Prove linearity works
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comps = [1, 4, 128, 2**34]
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sum_comps = 1+4+128+2**34
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y = 908
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z = _mult_gf2(sum_comps, y)
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w = 0
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for x in comps:
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w ^= _mult_gf2(x, y)
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self.assertEqual(w, z)
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def test_div_gf2(self):
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from Crypto.Util.number import size as deg
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x, y = _div_gf2(567, 7)
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self.assertTrue(deg(y) < deg(7))
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w = _mult_gf2(x, 7) ^ y
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self.assertEqual(567, w)
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x, y = _div_gf2(7, 567)
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self.assertEqual(x, 0)
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self.assertEqual(y, 7)
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class Element_Tests(TestCase):
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def test1(self):
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# Test encondings
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e = _Element(256)
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self.assertEqual(int(e), 256)
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self.assertEqual(e.encode(), bchr(0)*14 + b("\x01\x00"))
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e = _Element(bchr(0)*14 + b("\x01\x10"))
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self.assertEqual(int(e), 0x110)
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self.assertEqual(e.encode(), bchr(0)*14 + b("\x01\x10"))
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# Only 16 byte string are a valid encoding
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self.assertRaises(ValueError, _Element, bchr(0))
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def test2(self):
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# Test addition
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e = _Element(0x10)
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f = _Element(0x0A)
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self.assertEqual(int(e+f), 0x1A)
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def test3(self):
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# Test multiplication
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zero = _Element(0)
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one = _Element(1)
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two = _Element(2)
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x = _Element(6) * zero
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self.assertEqual(int(x), 0)
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x = _Element(6) * one
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self.assertEqual(int(x), 6)
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x = _Element(2**127) * two
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self.assertEqual(int(x), 1 + 2 + 4 + 128)
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def test4(self):
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# Test inversion
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one = _Element(1)
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x = one.inverse()
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self.assertEqual(int(x), 1)
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x = _Element(82323923)
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y = x.inverse()
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self.assertEqual(int(x * y), 1)
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class Shamir_Tests(TestCase):
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def test1(self):
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# Test splitting
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shares = Shamir.split(2, 3, bchr(90)*16)
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self.assertEqual(len(shares), 3)
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for index in range(3):
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self.assertEqual(shares[index][0], index+1)
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self.assertEqual(len(shares[index][1]), 16)
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def test2(self):
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# Test recombine
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# These shares were obtained with ssss v0.5:
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# ssss-split -t 2 -n 3 -s 128 -D -x
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secret = b("000102030405060708090a0b0c0d0e0f")
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shares = (
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(1,"0b8cbb92e2a750defa563537d72942a2"),
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(2,"171a7120c941abb4ecb77472ba459753"),
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(3,"1c97c8b12fe3fd6d1ee84b4e6161dbfe")
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)
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bin_shares = []
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for share in shares:
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bin_shares.append((share[0], unhexlify(b(share[1]))))
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result = Shamir.combine(bin_shares)
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self.assertEqual(hexlify(result), secret)
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def test3(self):
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# Loopback split/recombine
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secret = unhexlify(b("000102030405060708090a0b0c0d0e0f"))
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shares = Shamir.split(2, 3, secret)
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secret2 = Shamir.combine(shares[:2])
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self.assertEqual(secret, secret2)
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secret3 = Shamir.combine([ shares[0], shares[2] ])
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self.assertEqual(secret, secret3)
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secret4 = Shamir.combine(shares)
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self.assertEqual(secret, secret4) # One share too many
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def get_tests(config={}):
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tests = []
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tests += list_test_cases(GF2_Tests)
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tests += list_test_cases(Element_Tests)
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tests += list_test_cases(Shamir_Tests)
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return tests
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if __name__ == '__main__':
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suite = lambda: TestSuite(get_tests())
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main(defaultTest='suite')
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