# ===================================================================
#
# Copyright (c) 2015, Legrandin <helderijs@gmail.com>
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# modification, are permitted provided that the following conditions
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import unittest

from Crypto.SelfTest.st_common import list_test_cases
from Crypto.Util.py3compat import unhexlify, tobytes, bchr, b
from Crypto.Cipher import AES
from Crypto.Hash import SHAKE128


def get_tag_random(tag, length):
    return SHAKE128.new(data=tobytes(tag)).read(length)


class SivTests(unittest.TestCase):

    key_256 = get_tag_random("key_256", 32)
    key_384 = get_tag_random("key_384", 48)
    key_512 = get_tag_random("key_512", 64)
    nonce_96 = get_tag_random("nonce_128", 12)
    data_128 = get_tag_random("data_128", 16)

    def test_loopback_128(self):
        for key in self.key_256, self.key_384, self.key_512:
            cipher = AES.new(key, AES.MODE_SIV, nonce=self.nonce_96)
            pt = get_tag_random("plaintext", 16 * 100)
            ct, mac = cipher.encrypt_and_digest(pt)

            cipher = AES.new(key, AES.MODE_SIV, nonce=self.nonce_96)
            pt2 = cipher.decrypt_and_verify(ct, mac)
            self.assertEqual(pt, pt2)

    def test_nonce(self):
        # Deterministic encryption
        AES.new(self.key_256, AES.MODE_SIV)

        cipher = AES.new(self.key_256, AES.MODE_SIV, self.nonce_96)
        ct = cipher.encrypt(self.data_128)

        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        self.assertEqual(ct, cipher.encrypt(self.data_128))

    def test_nonce_must_be_bytes(self):
        self.assertRaises(TypeError, AES.new, self.key_256, AES.MODE_SIV,
                          nonce='test12345678')

    def test_nonce_length(self):
        # nonce can be of any length (but not empty)
        self.assertRaises(ValueError, AES.new, self.key_256, AES.MODE_SIV,
                          nonce=b(""))

        for x in range(1, 128):
            cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=bchr(1) * x)
            cipher.encrypt(bchr(1))

    def test_block_size_128(self):
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        self.assertEqual(cipher.block_size, AES.block_size)

    def test_nonce_attribute(self):
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        self.assertEqual(cipher.nonce, self.nonce_96)

        # By default, no nonce is randomly generated
        self.assertFalse(hasattr(AES.new(self.key_256, AES.MODE_SIV), "nonce"))

    def test_unknown_parameters(self):
        self.assertRaises(TypeError, AES.new, self.key_256, AES.MODE_SIV,
                          self.nonce_96, 7)
        self.assertRaises(TypeError, AES.new, self.key_256, AES.MODE_SIV,
                          nonce=self.nonce_96, unknown=7)

        # But some are only known by the base cipher
        # (e.g. use_aesni consumed by the AES module)
        AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96,
                use_aesni=False)

    def test_invalid_null_encryption(self):
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        self.assertRaises(ValueError, cipher.encrypt, b(""))

    def test_invalid_null_component(self):
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        self.assertRaises(ValueError, cipher.update, b(""))

    def test_encrypt_excludes_decrypt(self):
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        cipher.encrypt(self.data_128)
        self.assertRaises(TypeError, cipher.decrypt, self.data_128)

        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        cipher.encrypt(self.data_128)
        self.assertRaises(TypeError, cipher.decrypt_and_verify,
                          self.data_128, self.data_128)

    def test_data_must_be_bytes(self):
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        self.assertRaises(TypeError, cipher.encrypt, 'test1234567890-*')

        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        self.assertRaises(TypeError, cipher.decrypt_and_verify,
                          'test1234567890-*', b("xxxx"))

    def test_mac_len(self):
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        _, mac = cipher.encrypt_and_digest(self.data_128)
        self.assertEqual(len(mac), 16)

    def test_invalid_mac(self):
        from Crypto.Util.strxor import strxor_c
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        ct, mac = cipher.encrypt_and_digest(self.data_128)

        invalid_mac = strxor_c(mac, 0x01)

        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        self.assertRaises(ValueError, cipher.decrypt_and_verify, ct,
                          invalid_mac)

    def test_hex_mac(self):
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        mac_hex = cipher.hexdigest()
        self.assertEqual(cipher.digest(), unhexlify(mac_hex))

        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        cipher.hexverify(mac_hex)


class SivFSMTests(unittest.TestCase):

    key_256 = get_tag_random("key_256", 32)
    nonce_96 = get_tag_random("nonce_96", 12)
    data_128 = get_tag_random("data_128", 16)

    def test_valid_init_encrypt_decrypt_verify(self):
        # No authenticated data, fixed plaintext
        # Verify path INIT->ENCRYPT->DIGEST
        cipher = AES.new(self.key_256, AES.MODE_SIV,
                         nonce=self.nonce_96)
        ct = cipher.encrypt(self.data_128)
        mac = cipher.digest()

        # Verify path INIT->DECRYPT_AND_VERIFY
        cipher = AES.new(self.key_256, AES.MODE_SIV,
                         nonce=self.nonce_96)
        cipher.decrypt_and_verify(ct, mac)

    def test_invalid_init_decrypt(self):
        # Path INIT->DECRYPT fails
        cipher = AES.new(self.key_256, AES.MODE_SIV,
                         nonce=self.nonce_96)
        self.assertRaises(TypeError, cipher.decrypt, b("xxx"))

    def test_valid_init_update_digest_verify(self):
        # No plaintext, fixed authenticated data
        # Verify path INIT->UPDATE->DIGEST
        cipher = AES.new(self.key_256, AES.MODE_SIV,
                         nonce=self.nonce_96)
        cipher.update(self.data_128)
        mac = cipher.digest()

        # Verify path INIT->UPDATE->VERIFY
        cipher = AES.new(self.key_256, AES.MODE_SIV,
                         nonce=self.nonce_96)
        cipher.update(self.data_128)
        cipher.verify(mac)

    def test_valid_full_path(self):
        # Fixed authenticated data, fixed plaintext
        # Verify path INIT->UPDATE->ENCRYPT->DIGEST
        cipher = AES.new(self.key_256, AES.MODE_SIV,
                         nonce=self.nonce_96)
        cipher.update(self.data_128)
        ct = cipher.encrypt(self.data_128)
        mac = cipher.digest()

        # Verify path INIT->UPDATE->DECRYPT_AND_VERIFY
        cipher = AES.new(self.key_256, AES.MODE_SIV,
                         nonce=self.nonce_96)
        cipher.update(self.data_128)
        cipher.decrypt_and_verify(ct, mac)

    def test_valid_init_digest(self):
        # Verify path INIT->DIGEST
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        cipher.digest()

    def test_valid_init_verify(self):
        # Verify path INIT->VERIFY
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        mac = cipher.digest()

        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        cipher.verify(mac)

    def test_invalid_multiple_encrypt(self):
        # Without AAD
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        cipher.encrypt(b("xxx"))
        self.assertRaises(TypeError, cipher.encrypt, b("xxx"))

        # With AAD
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        cipher.update(b("yyy"))
        cipher.encrypt(b("xxx"))
        self.assertRaises(TypeError, cipher.encrypt, b("xxx"))

    def test_valid_multiple_digest_or_verify(self):
        # Multiple calls to digest
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        cipher.update(self.data_128)
        first_mac = cipher.digest()
        for x in range(4):
            self.assertEqual(first_mac, cipher.digest())

        # Multiple calls to verify
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        cipher.update(self.data_128)
        for x in range(5):
            cipher.verify(first_mac)

    def test_valid_encrypt_and_digest_decrypt_and_verify(self):
        # encrypt_and_digest
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        cipher.update(self.data_128)
        ct, mac = cipher.encrypt_and_digest(self.data_128)

        # decrypt_and_verify
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        cipher.update(self.data_128)
        pt = cipher.decrypt_and_verify(ct, mac)
        self.assertEqual(self.data_128, pt)

    def test_invalid_encrypt_or_update_after_digest(self):
        for method_name in "encrypt", "update":
            cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
            cipher.encrypt(self.data_128)
            cipher.digest()
            self.assertRaises(TypeError, getattr(cipher, method_name),
                              self.data_128)

            cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
            cipher.encrypt_and_digest(self.data_128)

    def test_invalid_decrypt_or_update_after_verify(self):
        cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
        ct = cipher.encrypt(self.data_128)
        mac = cipher.digest()

        for method_name in "decrypt", "update":
            cipher = AES.new(self.key_256, AES.MODE_SIV, nonce=self.nonce_96)
            cipher.decrypt_and_verify(ct, mac)
            self.assertRaises(TypeError, getattr(cipher, method_name),
                              self.data_128)


class TestVectors(unittest.TestCase):
    """Class exercising the SIV test vectors found in RFC5297"""

    # This is a list of tuples with 5 items:
    #
    #  1. Header + '|' + plaintext
    #  2. Header + '|' + ciphertext + '|' + MAC
    #  3. AES-128 key
    #  4. Description
    #  5. Dictionary of parameters to be passed to AES.new().
    #     It must include the nonce.
    #
    #  A "Header" is a dash ('-') separated sequece of components.
    #
    test_vectors = [
      (
        '101112131415161718191a1b1c1d1e1f2021222324252627',
        '112233445566778899aabbccddee',
        '40c02b9690c4dc04daef7f6afe5c',
        '85632d07c6e8f37f950acd320a2ecc93',
        'fffefdfcfbfaf9f8f7f6f5f4f3f2f1f0f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff',
        None
      ),
      (
        '00112233445566778899aabbccddeeffdeaddadadeaddadaffeeddccbbaa9988' +
        '7766554433221100-102030405060708090a0',
        '7468697320697320736f6d6520706c61696e7465787420746f20656e63727970' +
        '74207573696e67205349562d414553',
        'cb900f2fddbe404326601965c889bf17dba77ceb094fa663b7a3f748ba8af829' +
        'ea64ad544a272e9c485b62a3fd5c0d',
        '7bdb6e3b432667eb06f4d14bff2fbd0f',
        '7f7e7d7c7b7a79787776757473727170404142434445464748494a4b4c4d4e4f',
        '09f911029d74e35bd84156c5635688c0'
      ),
    ]

    for index, tv in enumerate(test_vectors):
        test_vectors[index] = [[unhexlify(x) for x in tv[0].split("-")]]
        test_vectors[index] += [unhexlify(x) for x in tv[1:5]]
        if tv[5]:
            nonce = unhexlify(tv[5])
        else:
            nonce = None
        test_vectors[index].append(nonce)

    def runTest(self):
        for assoc_data, pt, ct, mac, key, nonce in self.test_vectors:

            # Encrypt
            cipher = AES.new(key, AES.MODE_SIV, nonce=nonce)
            for x in assoc_data:
                cipher.update(x)
            ct2, mac2 = cipher.encrypt_and_digest(pt)
            self.assertEqual(ct, ct2)
            self.assertEqual(mac, mac2)

            # Decrypt
            cipher = AES.new(key, AES.MODE_SIV, nonce=nonce)
            for x in assoc_data:
                cipher.update(x)
            pt2 = cipher.decrypt_and_verify(ct, mac)
            self.assertEqual(pt, pt2)


def get_tests(config={}):
    tests = []
    tests += list_test_cases(SivTests)
    tests += list_test_cases(SivFSMTests)
    tests += [TestVectors()]
    return tests


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