4 def base64_from_hex(_hex):
5 return codecs.encode(bytes.fromhex(_hex), 'base64').decode('utf-8')
7 def xor_bytes(bytes0, bytes1):
8 return bytes(b0 ^ b1 for b0, b1 in zip(bytes0, bytes1))
10 def xor_hex(hex0, hex1):
11 assert len(hex0) == len(hex1)
12 bytes0 = bytes.fromhex(hex0)
13 bytes1 = bytes.fromhex(hex1)
14 return codecs.encode(xor_bytes(bytes0, bytes1), 'hex').decode('utf-8')
16 def get_character_frequencies(source):
19 for source_character in source:
20 frequencies[source_character] = frequencies.get(source_character, 0) + 1
24 def compare_frequency_deviation(base_frequency, comparison_frequency):
26 abs(frequency - comparison_frequency.get(character, 0))
27 for character, frequency in base_frequency.items()
28 ) / len(base_frequency)
30 class Set1Challenge1Tests(unittest.TestCase):
31 def test_converts_hex_to_base64(self):
32 expected = 'SSdtIGtpbGxpbmcgeW91ciBicmFpbiBsaWtlIGEgcG9pc29ub3VzIG11c2hyb29t\n'
33 actual = base64_from_hex('49276d206b696c6c696e6720796f757220627261696e206c696b65206120706f69736f6e6f7573206d757368726f6f6d')
34 self.assertEqual(expected, actual)
36 class Set1Challenge2Tests(unittest.TestCase):
37 def test_xors_hex_strings(self):
38 hex0 = '1c0111001f010100061a024b53535009181c'
39 hex1 = '686974207468652062756c6c277320657965'
41 expected = '746865206b696420646f6e277420706c6179'
42 actual = xor_hex(hex0, hex1)
44 self.assertEqual(expected, actual)
46 class Set1Challenge3Tests(unittest.TestCase):
47 def test_gets_message(self):
48 with open('sample.txt','r') as sample_file:
49 sample_text = sample_file.read()
51 sample_frequencies = get_character_frequencies(sample_text)
53 xored_string = bytes.fromhex('1b37373331363f78151b7f2b783431333d78397828372d363c78373e783a393b3736')
55 lowest_frequency_deviation_string = None
56 lowest_frequency_deviation = None
59 key_char = bytes([i]).decode('utf-8')
60 key = bytes([i]) * len(xored_string)
61 try_string = xor_bytes(xored_string, key).decode('utf-8')
62 try_string_frequency_deviation = compare_frequency_deviation(
64 get_character_frequencies(try_string),
67 if lowest_frequency_deviation is None or try_string_frequency_deviation < lowest_frequency_deviation:
68 lowest_frequency_deviation_string = try_string
69 lowest_frequency_deviation = try_string_frequency_deviation
72 expected = "Cooking MC's like a pound of bacon"
73 actual = lowest_frequency_deviation_string
75 self.assertEqual(expected, actual)
77 if __name__ == '__main__':