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jvdsn
GitHub Repository: jvdsn/crypto-attacks
 Path: blob/master/test/test_elgamal_encryption.py
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import os

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import sys

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from random import randrange

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from unittest import TestCase

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from sage.all import legendre_symbol

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path = os.path.dirname(os.path.dirname(os.path.realpath(os.path.abspath(__file__))))

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if sys.path[1] != path:

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    sys.path.insert(1, path)

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from attacks.elgamal_encryption import nonce_reuse

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from attacks.elgamal_encryption import unsafe_generator

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class TestElgamalEncryption(TestCase):

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    def test_nonce_reuse(self):

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        # Safe prime.

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        p = 16902648776703029279

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        g = 3

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        for _ in range(100):

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            x = randrange(1, p)

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            h = pow(g, x, p)

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            y = randrange(1, p)

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            s = pow(h, y, p)

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            m = randrange(1, p)

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            c1 = pow(g, y, p)

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            c2 = m * s % p

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            m_ = randrange(1, p)

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            c1_ = pow(g, y, p)

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            c2_ = m_ * s % p

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            m__ = nonce_reuse.attack(p, m, c1, c2, c1_, c2_)

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            self.assertIsInstance(m__, int)

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            self.assertEqual(m_, m__)

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    def test_unsafe_generator(self):

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        # Safe prime.

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        p = 16902648776703029279

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        # Unsafe generator, generates the entire group.

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        g = 7

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        for _ in range(100):

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            x = randrange(1, p)

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            h = pow(g, x, p)

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            y = randrange(1, p)

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            s = pow(h, y, p)

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            m = randrange(1, p)

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            c1 = pow(g, y, p)

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            c2 = m * s % p

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            k = unsafe_generator.attack(p, h, c1, c2)

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            self.assertIsInstance(k, int)

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            self.assertEqual(legendre_symbol(m, p), k)

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