# -*- coding: utf-8 -*-
#
#  SelfTest/PublicKey/test_DSA.py: Self-test for the DSA primitive
#
# Written in 2008 by Dwayne C. Litzenberger <dlitz@dlitz.net>
#
# ===================================================================
# The contents of this file are dedicated to the public domain.  To
# the extent that dedication to the public domain is not available,
# everyone is granted a worldwide, perpetual, royalty-free,
# non-exclusive license to exercise all rights associated with the
# contents of this file for any purpose whatsoever.
# No rights are reserved.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
# ===================================================================

"""Self-test suite for Cryptodome.PublicKey.DSA"""

import os
from Cryptodome.Util.py3compat import *

import unittest
from Cryptodome.SelfTest.st_common import list_test_cases, a2b_hex, b2a_hex

def _sws(s):
    """Remove whitespace from a text or byte string"""
    if isinstance(s,str):
        return "".join(s.split())
    else:
        return b("").join(s.split())

class DSATest(unittest.TestCase):
    # Test vector from "Appendix 5. Example of the DSA" of
    # "Digital Signature Standard (DSS)",
    # U.S. Department of Commerce/National Institute of Standards and Technology
    # FIPS 186-2 (+Change Notice), 2000 January 27.
    # http://csrc.nist.gov/publications/fips/fips186-2/fips186-2-change1.pdf

    y = _sws("""19131871 d75b1612 a819f29d 78d1b0d7 346f7aa7 7bb62a85
                9bfd6c56 75da9d21 2d3a36ef 1672ef66 0b8c7c25 5cc0ec74
                858fba33 f44c0669 9630a76b 030ee333""")

    g = _sws("""626d0278 39ea0a13 413163a5 5b4cb500 299d5522 956cefcb
                3bff10f3 99ce2c2e 71cb9de5 fa24babf 58e5b795 21925c9c
                c42e9f6f 464b088c c572af53 e6d78802""")

    p = _sws("""8df2a494 492276aa 3d25759b b06869cb eac0d83a fb8d0cf7
                cbb8324f 0d7882e5 d0762fc5 b7210eaf c2e9adac 32ab7aac
                49693dfb f83724c2 ec0736ee 31c80291""")

    q = _sws("""c773218c 737ec8ee 993b4f2d ed30f48e dace915f""")

    x = _sws("""2070b322 3dba372f de1c0ffc 7b2e3b49 8b260614""")

    k = _sws("""358dad57 1462710f 50e254cf 1a376b2b deaadfbf""")
    k_inverse = _sws("""0d516729 8202e49b 4116ac10 4fc3f415 ae52f917""")
    m = b2a_hex(b("abc"))
    m_hash = _sws("""a9993e36 4706816a ba3e2571 7850c26c 9cd0d89d""")
    r = _sws("""8bac1ab6 6410435c b7181f95 b16ab97c 92b341c0""")
    s = _sws("""41e2345f 1f56df24 58f426d1 55b4ba2d b6dcd8c8""")

    def setUp(self):
        global DSA, Random, bytes_to_long, size
        from Cryptodome.PublicKey import DSA
        from Cryptodome import Random
        from Cryptodome.Util.number import bytes_to_long, inverse, size

        self.dsa = DSA

    def test_generate_1arg(self):
        """DSA (default implementation) generated key (1 argument)"""
        dsaObj = self.dsa.generate(1024)
        self._check_private_key(dsaObj)
        pub = dsaObj.publickey()
        self._check_public_key(pub)

    def test_generate_2arg(self):
        """DSA (default implementation) generated key (2 arguments)"""
        dsaObj = self.dsa.generate(1024, Random.new().read)
        self._check_private_key(dsaObj)
        pub = dsaObj.publickey()
        self._check_public_key(pub)

    def test_construct_4tuple(self):
        """DSA (default implementation) constructed key (4-tuple)"""
        (y, g, p, q) = [bytes_to_long(a2b_hex(param)) for param in (self.y, self.g, self.p, self.q)]
        dsaObj = self.dsa.construct((y, g, p, q))
        self._test_verification(dsaObj)

    def test_construct_5tuple(self):
        """DSA (default implementation) constructed key (5-tuple)"""
        (y, g, p, q, x) = [bytes_to_long(a2b_hex(param)) for param in (self.y, self.g, self.p, self.q, self.x)]
        dsaObj = self.dsa.construct((y, g, p, q, x))
        self._test_signing(dsaObj)
        self._test_verification(dsaObj)

    def test_construct_bad_key4(self):
        (y, g, p, q) = [bytes_to_long(a2b_hex(param)) for param in (self.y, self.g, self.p, self.q)]
        tup = (y, g, p+1, q)
        self.assertRaises(ValueError, self.dsa.construct, tup)

        tup = (y, g, p, q+1)
        self.assertRaises(ValueError, self.dsa.construct, tup)

        tup = (y, 1, p, q)
        self.assertRaises(ValueError, self.dsa.construct, tup)

    def test_construct_bad_key5(self):
        (y, g, p, q, x) = [bytes_to_long(a2b_hex(param)) for param in (self.y, self.g, self.p, self.q, self.x)]
        tup = (y, g, p, q, x+1)
        self.assertRaises(ValueError, self.dsa.construct, tup)

        tup = (y, g, p, q, q+10)
        self.assertRaises(ValueError, self.dsa.construct, tup)

    def _check_private_key(self, dsaObj):
        # Check capabilities
        self.assertEqual(1, dsaObj.has_private())
        self.assertEqual(1, dsaObj.can_sign())
        self.assertEqual(0, dsaObj.can_encrypt())

        # Sanity check key data
        self.assertEqual(1, dsaObj.p > dsaObj.q)            # p > q
        self.assertEqual(160, size(dsaObj.q))               # size(q) == 160 bits
        self.assertEqual(0, (dsaObj.p - 1) % dsaObj.q)      # q is a divisor of p-1
        self.assertEqual(dsaObj.y, pow(dsaObj.g, dsaObj.x, dsaObj.p))     # y == g**x mod p
        self.assertEqual(1, 0 < dsaObj.x < dsaObj.q)       # 0 < x < q

    def _check_public_key(self, dsaObj):
        k = bytes_to_long(a2b_hex(self.k))
        m_hash = bytes_to_long(a2b_hex(self.m_hash))

        # Check capabilities
        self.assertEqual(0, dsaObj.has_private())
        self.assertEqual(1, dsaObj.can_sign())
        self.assertEqual(0, dsaObj.can_encrypt())

        # Check that private parameters are all missing
        self.assertEqual(0, hasattr(dsaObj, 'x'))

        # Sanity check key data
        self.assertEqual(1, dsaObj.p > dsaObj.q)            # p > q
        self.assertEqual(160, size(dsaObj.q))               # size(q) == 160 bits
        self.assertEqual(0, (dsaObj.p - 1) % dsaObj.q)      # q is a divisor of p-1

        # Public-only key objects should raise an error when .sign() is called
        self.assertRaises(TypeError, dsaObj._sign, m_hash, k)

        # Check __eq__ and __ne__
        self.assertEqual(dsaObj.publickey() == dsaObj.publickey(),True) # assert_
        self.assertEqual(dsaObj.publickey() != dsaObj.publickey(),False) # failIf

    def _test_signing(self, dsaObj):
        k = bytes_to_long(a2b_hex(self.k))
        m_hash = bytes_to_long(a2b_hex(self.m_hash))
        r = bytes_to_long(a2b_hex(self.r))
        s = bytes_to_long(a2b_hex(self.s))
        (r_out, s_out) = dsaObj._sign(m_hash, k)
        self.assertEqual((r, s), (r_out, s_out))

    def _test_verification(self, dsaObj):
        m_hash = bytes_to_long(a2b_hex(self.m_hash))
        r = bytes_to_long(a2b_hex(self.r))
        s = bytes_to_long(a2b_hex(self.s))
        self.failUnless(dsaObj._verify(m_hash, (r, s)))
        self.failIf(dsaObj._verify(m_hash + 1, (r, s)))


class DSADomainTest(unittest.TestCase):

    def test_domain1(self):
        """Verify we can generate new keys in a given domain"""
        dsa_key_1 = DSA.generate(1024)
        domain_params = dsa_key_1.domain()

        dsa_key_2 = DSA.generate(1024, domain=domain_params)
        self.assertEqual(dsa_key_1.p, dsa_key_2.p)
        self.assertEqual(dsa_key_1.q, dsa_key_2.q)
        self.assertEqual(dsa_key_1.g, dsa_key_2.g)

        self.assertEqual(dsa_key_1.domain(), dsa_key_2.domain())

    def _get_weak_domain(self):

        from Cryptodome.Math.Numbers import Integer
        from Cryptodome.Math import Primality

        p = Integer(4)
        while p.size_in_bits() != 1024 or Primality.test_probable_prime(p) != Primality.PROBABLY_PRIME:
            q1 = Integer.random(exact_bits=80)
            q2 = Integer.random(exact_bits=80)
            q = q1 * q2
            z = Integer.random(exact_bits=1024-160)
            p = z * q + 1

        h = Integer(2)
        g = 1
        while g == 1:
            g = pow(h, z, p)
            h += 1

        return (p, q, g)


    def test_generate_error_weak_domain(self):
        """Verify that domain parameters with composite q are rejected"""

        domain_params = self._get_weak_domain()
        self.assertRaises(ValueError, DSA.generate, 1024, domain=domain_params)


    def test_construct_error_weak_domain(self):
        """Verify that domain parameters with composite q are rejected"""

        from Cryptodome.Math.Numbers import Integer

        p, q, g = self._get_weak_domain()
        y =  pow(g, 89, p)
        self.assertRaises(ValueError, DSA.construct, (y, g, p, q))


def get_tests(config={}):
    tests = []
    tests += list_test_cases(DSATest)
    tests += list_test_cases(DSADomainTest)
    return tests

if __name__ == '__main__':
    suite = lambda: unittest.TestSuite(get_tests())
    unittest.main(defaultTest='suite')

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