# ===================================================================
#
# Copyright (c) 2018, Helder Eijs <helderijs@gmail.com>
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import json
import unittest
from binascii import unhexlify

from Crypto.SelfTest.st_common import list_test_cases
from Crypto.Util.py3compat import tobytes, _memoryview
from Crypto.Cipher import ChaCha20_Poly1305
from Crypto.Hash import SHAKE128

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 ChaCha20Poly1305Tests(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_loopback(self):
        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        pt = get_tag_random("plaintext", 16 * 100)
        ct = cipher.encrypt(pt)

        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        pt2 = cipher.decrypt(ct)
        self.assertEqual(pt, pt2)

    def test_nonce(self):
        # Nonce can only be 8 or 12 bytes
        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=b'H' * 8)
        self.assertEqual(len(cipher.nonce), 8)
        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=b'H' * 12)
        self.assertEqual(len(cipher.nonce), 12)

        # If not passed, the nonce is created randomly
        cipher = ChaCha20_Poly1305.new(key=self.key_256)
        nonce1 = cipher.nonce
        cipher = ChaCha20_Poly1305.new(key=self.key_256)
        nonce2 = cipher.nonce
        self.assertEqual(len(nonce1), 12)
        self.assertNotEqual(nonce1, nonce2)

        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        ct = cipher.encrypt(self.data_128)

        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        self.assertEquals(ct, cipher.encrypt(self.data_128))

    def test_nonce_must_be_bytes(self):
        self.assertRaises(TypeError,
                          ChaCha20_Poly1305.new,
                          key=self.key_256,
                          nonce=u'test12345678')

    def test_nonce_length(self):
        # nonce can only be 8 or 12 bytes long
        self.assertRaises(ValueError,
                          ChaCha20_Poly1305.new,
                          key=self.key_256,
                          nonce=b'0' * 7)
        self.assertRaises(ValueError,
                          ChaCha20_Poly1305.new,
                          key=self.key_256,
                          nonce=b'')

    def test_block_size(self):
        # Not based on block ciphers
        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        self.failIf(hasattr(cipher, 'block_size'))

    def test_nonce_attribute(self):
        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        self.assertEqual(cipher.nonce, self.nonce_96)

        # By default, a 12 bytes long nonce is randomly generated
        nonce1 = ChaCha20_Poly1305.new(key=self.key_256).nonce
        nonce2 = ChaCha20_Poly1305.new(key=self.key_256).nonce
        self.assertEqual(len(nonce1), 12)
        self.assertNotEqual(nonce1, nonce2)

    def test_unknown_parameters(self):
        self.assertRaises(TypeError,
                          ChaCha20_Poly1305.new,
                          key=self.key_256,
                          param=9)

    def test_null_encryption_decryption(self):
        for func in "encrypt", "decrypt":
            cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                           nonce=self.nonce_96)
            result = getattr(cipher, func)(b"")
            self.assertEqual(result, b"")

    def test_either_encrypt_or_decrypt(self):
        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        cipher.encrypt(b"")
        self.assertRaises(TypeError, cipher.decrypt, b"")

        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        cipher.decrypt(b"")
        self.assertRaises(TypeError, cipher.encrypt, b"")

    def test_data_must_be_bytes(self):
        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        self.assertRaises(TypeError, cipher.encrypt, u'test1234567890-*')

        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        self.assertRaises(TypeError, cipher.decrypt, u'test1234567890-*')

    def test_mac_len(self):
        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       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 = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        ct, mac = cipher.encrypt_and_digest(self.data_128)

        invalid_mac = strxor_c(mac, 0x01)

        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        self.assertRaises(ValueError, cipher.decrypt_and_verify, ct,
                          invalid_mac)

    def test_hex_mac(self):
        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        mac_hex = cipher.hexdigest()
        self.assertEqual(cipher.digest(), unhexlify(mac_hex))

        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       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 = ChaCha20_Poly1305.new(key=self.key_256,
                                       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 = ChaCha20_Poly1305.new(key=self.key_256,
                                           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 = ChaCha20_Poly1305.new(key=self.key_256,
                                           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_256)
        nonce_ba = bytearray(self.nonce_96)
        header_ba = bytearray(self.data_128)
        data_ba = bytearray(self.data_128)

        cipher1 = ChaCha20_Poly1305.new(key=self.key_256,
                                        nonce=self.nonce_96)
        cipher1.update(self.data_128)
        ct = cipher1.encrypt(self.data_128)
        tag = cipher1.digest()

        cipher2 = ChaCha20_Poly1305.new(key=self.key_256,
                                        nonce=self.nonce_96)
        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'\x99\x99\x99'
        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_256)
        nonce_ba = bytearray(self.nonce_96)
        header_ba = bytearray(self.data_128)
        ct_ba = bytearray(ct)
        tag_ba = bytearray(tag)
        del data_ba

        cipher3 = ChaCha20_Poly1305.new(key=self.key_256,
                                        nonce=self.nonce_96)
        key_ba[:3] = b'\xFF\xFF\xFF'
        nonce_ba[:3] = b'\xFF\xFF\xFF'
        cipher3.update(header_ba)
        header_ba[:3] = b'\xFF\xFF\xFF'
        pt_test = cipher3.decrypt(ct_ba)
        ct_ba[:3] = b'\xFF\xFF\xFF'
        cipher3.verify(tag_ba)

        self.assertEqual(pt_test, self.data_128)

    def test_memoryview(self):

        # Encrypt
        key_mv = memoryview(bytearray(self.key_256))
        nonce_mv = memoryview(bytearray(self.nonce_96))
        header_mv = memoryview(bytearray(self.data_128))
        data_mv = memoryview(bytearray(self.data_128))

        cipher1 = ChaCha20_Poly1305.new(key=self.key_256,
                                        nonce=self.nonce_96)
        cipher1.update(self.data_128)
        ct = cipher1.encrypt(self.data_128)
        tag = cipher1.digest()

        cipher2 = ChaCha20_Poly1305.new(key=self.key_256,
                                        nonce=self.nonce_96)
        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'\x99\x99\x99'
        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_256))
        nonce_mv = memoryview(bytearray(self.nonce_96))
        header_mv = memoryview(bytearray(self.data_128))
        ct_mv = memoryview(bytearray(ct))
        tag_mv = memoryview(bytearray(tag))
        del data_mv

        cipher3 = ChaCha20_Poly1305.new(key=self.key_256,
                                        nonce=self.nonce_96)
        key_mv[:3] = b'\xFF\xFF\xFF'
        nonce_mv[:3] = b'\xFF\xFF\xFF'
        cipher3.update(header_mv)
        header_mv[:3] = b'\xFF\xFF\xFF'
        pt_test = cipher3.decrypt(ct_mv)
        ct_mv[:3] = b'\x99\x99\x99'
        cipher3.verify(tag_mv)

        self.assertEqual(pt_test, self.data_128)

    import sys
    if sys.version[:3] == "2.6":
        del test_memoryview


class ChaCha20Poly1305FSMTests(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_digest_verify(self):
        # No authenticated data, fixed plaintext
        # Verify path INIT->ENCRYPT->DIGEST
        cipher = ChaCha20_Poly1305.new(key=self.key_256,
                                       nonce=self.nonce_96)
        ct = cipher.encrypt(self.data_128)
        mac = cipher.digest()

        # Verify path INIT->DECRYPT->VERIFY