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# Copyright (c) 2015, Legrandin <helderijs@gmail.com>
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from __future__ import print_function

import json
import unittest
from binascii import unhexlify

from Crypto.SelfTest.st_common import list_test_cases
from Crypto.SelfTest.loader import load_tests

from Crypto.Util.py3compat import tobytes, bchr, _memoryview
from Crypto.Cipher import AES
from Crypto.Hash import SHAKE128, SHA256

from Crypto.Util._file_system import pycryptodome_filename
from Crypto.Util.strxor import strxor


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


class GcmTests(unittest.TestCase):

    key_128 = get_tag_random("key_128", 16)
    nonce_96 = get_tag_random("nonce_128", 12)
    data_128 = get_tag_random("data_128", 16)

    def test_loopback_128(self):
        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        pt = get_tag_random("plaintext", 16 * 100)
        ct = cipher.encrypt(pt)

        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        pt2 = cipher.decrypt(ct)
        self.assertEqual(pt, pt2)

    def test_nonce(self):
        # Nonce is optional (a random one will be created)
        AES.new(self.key_128, AES.MODE_GCM)

        cipher = AES.new(self.key_128, AES.MODE_GCM, self.nonce_96)
        ct = cipher.encrypt(self.data_128)

        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        self.assertEquals(ct, cipher.encrypt(self.data_128))

    def test_nonce_must_be_bytes(self):
        self.assertRaises(TypeError, AES.new, self.key_128, AES.MODE_GCM,
                          nonce=u'test12345678')

    def test_nonce_length(self):
        # nonce can be of any length (but not empty)
        self.assertRaises(ValueError, AES.new, self.key_128, AES.MODE_GCM,
                          nonce=b"")

        for x in range(1, 128):
            cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=bchr(1) * x)
            cipher.encrypt(bchr(1))

    def test_block_size_128(self):
        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        self.assertEqual(cipher.block_size, AES.block_size)

    def test_nonce_attribute(self):
        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        self.assertEqual(cipher.nonce, self.nonce_96)

        # By default, a 15 bytes long nonce is randomly generated
        nonce1 = AES.new(self.key_128, AES.MODE_GCM).nonce
        nonce2 = AES.new(self.key_128, AES.MODE_GCM).nonce
        self.assertEqual(len(nonce1), 16)
        self.assertNotEqual(nonce1, nonce2)

    def test_unknown_parameters(self):
        self.assertRaises(TypeError, AES.new, self.key_128, AES.MODE_GCM,
                          self.nonce_96, 7)
        self.assertRaises(TypeError, AES.new, self.key_128, AES.MODE_GCM,
                          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_128, AES.MODE_GCM, nonce=self.nonce_96,
                use_aesni=False)

    def test_null_encryption_decryption(self):
        for func in "encrypt", "decrypt":
            cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
            result = getattr(cipher, func)(b"")
            self.assertEqual(result, b"")

    def test_either_encrypt_or_decrypt(self):
        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        cipher.encrypt(b"")
        self.assertRaises(TypeError, cipher.decrypt, b"")

        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        cipher.decrypt(b"")
        self.assertRaises(TypeError, cipher.encrypt, b"")

    def test_data_must_be_bytes(self):
        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        self.assertRaises(TypeError, cipher.encrypt, u'test1234567890-*')

        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        self.assertRaises(TypeError, cipher.decrypt, u'test1234567890-*')

    def test_mac_len(self):
        # Invalid MAC length
        self.assertRaises(ValueError, AES.new, self.key_128, AES.MODE_GCM,
                          nonce=self.nonce_96, mac_len=3)
        self.assertRaises(ValueError, AES.new, self.key_128, AES.MODE_GCM,
                          nonce=self.nonce_96, mac_len=16+1)

        # Valid MAC length
        for mac_len in range(5, 16 + 1):
            cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96,
                             mac_len=mac_len)
            _, mac = cipher.encrypt_and_digest(self.data_128)
            self.assertEqual(len(mac), mac_len)

        # Default MAC length
        cipher = AES.new(self.key_128, AES.MODE_GCM, 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_128, AES.MODE_GCM, nonce=self.nonce_96)
        ct, mac = cipher.encrypt_and_digest(self.data_128)

        invalid_mac = strxor_c(mac, 0x01)

        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        self.assertRaises(ValueError, cipher.decrypt_and_verify, ct,
                          invalid_mac)

    def test_hex_mac(self):
        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        mac_hex = cipher.hexdigest()
        self.assertEqual(cipher.digest(), unhexlify(mac_hex))

        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        cipher.hexverify(mac_hex)

    def test_message_chunks(self):
        # Validate that both associated data and plaintext/ciphertext
        # can be broken up in chunks of arbitrary length

        auth_data = get_tag_random("authenticated data", 127)
        plaintext = get_tag_random("plaintext", 127)

        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        cipher.update(auth_data)
        ciphertext, ref_mac = cipher.encrypt_and_digest(plaintext)

        def break_up(data, chunk_length):
            return [data[i:i+chunk_length] for i in range(0, len(data),
                    chunk_length)]

        # Encryption
        for chunk_length in 1, 2, 3, 7, 10, 13, 16, 40, 80, 128:

            cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)

            for chunk in break_up(auth_data, chunk_length):
                cipher.update(chunk)
            pt2 = b""
            for chunk in break_up(ciphertext, chunk_length):
                pt2 += cipher.decrypt(chunk)
            self.assertEqual(plaintext, pt2)
            cipher.verify(ref_mac)

        # Decryption
        for chunk_length in 1, 2, 3, 7, 10, 13, 16, 40, 80, 128:

            cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)

            for chunk in break_up(auth_data, chunk_length):
                cipher.update(chunk)
            ct2 = b""
            for chunk in break_up(plaintext, chunk_length):
                ct2 += cipher.encrypt(chunk)
            self.assertEqual(ciphertext, ct2)
            self.assertEquals(cipher.digest(), ref_mac)

    def test_bytearray(self):

        # Encrypt
        key_ba = bytearray(self.key_128)
        nonce_ba = bytearray(self.nonce_96)
        header_ba = bytearray(self.data_128)
        data_ba = bytearray(self.data_128)

        cipher1 = AES.new(self.key_128,
                          AES.MODE_GCM,
                          nonce=self.nonce_96)
        cipher1.update(self.data_128)
        ct = cipher1.encrypt(self.data_128)
        tag = cipher1.digest()

        cipher2 = AES.new(key_ba,
                          AES.MODE_GCM,
                          nonce=nonce_ba)
        key_ba[:3] = b"\xFF\xFF\xFF"
        nonce_ba[:3] = b"\xFF\xFF\xFF"
        cipher2.update(header_ba)
        header_ba[:3] = b"\xFF\xFF\xFF"
        ct_test = cipher2.encrypt(data_ba)
        data_ba[:3] = b"\xFF\xFF\xFF"
        tag_test = cipher2.digest()

        self.assertEqual(ct, ct_test)
        self.assertEqual(tag, tag_test)
        self.assertEqual(cipher1.nonce, cipher2.nonce)

        # Decrypt
        key_ba = bytearray(self.key_128)
        nonce_ba = bytearray(self.nonce_96)
        header_ba = bytearray(self.data_128)
        del data_ba

        cipher4 = AES.new(key_ba,
                          AES.MODE_GCM,
                          nonce=nonce_ba)
        key_ba[:3] = b"\xFF\xFF\xFF"
        nonce_ba[:3] = b"\xFF\xFF\xFF"
        cipher4.update(header_ba)
        header_ba[:3] = b"\xFF\xFF\xFF"
        pt_test = cipher4.decrypt_and_verify(bytearray(ct_test), bytearray(tag_test))

        self.assertEqual(self.data_128, pt_test)

    def test_memoryview(self):

        # Encrypt
        key_mv = memoryview(bytearray(self.key_128))
        nonce_mv = memoryview(bytearray(self.nonce_96))
        header_mv = memoryview(bytearray(self.data_128))
        data_mv = memoryview(bytearray(self.data_128))

        cipher1 = AES.new(self.key_128,
                          AES.MODE_GCM,
                          nonce=self.nonce_96)
        cipher1.update(self.data_128)
        ct = cipher1.encrypt(self.data_128)
        tag = cipher1.digest()

        cipher2 = AES.new(key_mv,
                          AES.MODE_GCM,
                          nonce=nonce_mv)
        key_mv[:3] = b"\xFF\xFF\xFF"
        nonce_mv[:3] = b"\xFF\xFF\xFF"
        cipher2.update(header_mv)
        header_mv[:3] = b"\xFF\xFF\xFF"
        ct_test = cipher2.encrypt(data_mv)
        data_mv[:3] = b"\xFF\xFF\xFF"
        tag_test = cipher2.digest()

        self.assertEqual(ct, ct_test)
        self.assertEqual(tag, tag_test)
        self.assertEqual(cipher1.nonce, cipher2.nonce)

        # Decrypt
        key_mv = memoryview(bytearray(self.key_128))
        nonce_mv = memoryview(bytearray(self.nonce_96))
        header_mv = memoryview(bytearray(self.data_128))
        del data_mv

        cipher4 = AES.new(key_mv,
                          AES.MODE_GCM,
                          nonce=nonce_mv)
        key_mv[:3] = b"\xFF\xFF\xFF"
        nonce_mv[:3] = b"\xFF\xFF\xFF"
        cipher4.update(header_mv)
        header_mv[:3] = b"\xFF\xFF\xFF"
        pt_test = cipher4.decrypt_and_verify(memoryview(ct_test), memoryview(tag_test))

        self.assertEqual(self.data_128, pt_test)
    
    def test_output_param(self):

        pt = b'5' * 16
        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        ct = cipher.encrypt(pt)
        tag = cipher.digest()

        output = bytearray(16)
        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        res = cipher.encrypt(pt, output=output)
        self.assertEqual(ct, output)
        self.assertEqual(res, None)
        
        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        res = cipher.decrypt(ct, output=output)
        self.assertEqual(pt, output)
        self.assertEqual(res, None)
        
        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        res, tag_out = cipher.encrypt_and_digest(pt, output=output)
        self.assertEqual(ct, output)
        self.assertEqual(res, None)
        self.assertEqual(tag, tag_out)
        
        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        res = cipher.decrypt_and_verify(ct, tag, output=output)
        self.assertEqual(pt, output)
        self.assertEqual(res, None)

    def test_output_param_memoryview(self):
        
        pt = b'5' * 16
        cipher = AES.new(self.key_128, AES.MODE_GCM, nonce=self.nonce_96)
        ct = cipher.encrypt(pt)

        output = memoryview(bytearray(16))