def test(key_length):
if args.verbose:
print(f"Testing key length {key_length}")
groups = []
for n in range(1, key_length + 1):
groups.append(subgroup(n, key_length))
a = ord('A')
key = ""
for n, group in enumerate(groups):
coef = utils.coincidence_index(group)
if args.all:
print(f"Subgroup {n + 1} (IC: {coef})\n{group}")
best_subkey = ('A', 0)
for i in range(MODULE):
shift = (MODULE - i)%MODULE
decrypt = caesar.caesar(group, shift)
frequencies = utils.most_frequent_chars(decrypt)
score = utils.match_score(''.join(map(lambda x: x[0], frequencies)))
subkey = chr(a + i)
if args.all:
print(f"Testing subkey '{subkey}' with match score {round(100 * (score/MAX_SCORE))}%")
if best_subkey[1] < score:
best_subkey = (subkey, score)
if args.all:
print(f"Best subkey is '{best_subkey[0]}' with match score {round(100 * (best_subkey[1]/MAX_SCORE))}%")
key += best_subkey[0]
decrypt = vigenere(text, key)
return (key, decrypt) if validator.is_valid(decrypt) else FAILED
def friedman(text, frequencies=None):
kp = ENGLISH_IC
kr = MIN_ENGLISH_IC
ko = utils.coincidence_index(text, frequencies)
return (ko, math.ceil((kp - kr)/(ko - kr)))