def crack3b(ciphertext):
ciphertext = [text.strip() for text in ciphertext.split("|")]
# parse the input
orig_sentence = ciphertext[1]
sentence = part2.sanitize_input(orig_sentence)
key_length = int(ciphertext[0])
best_key = None
best_score = None
for seed in range(5):
random.seed(seed)
curr_key = tuple(random.randint(0, 26) for _ in range(key_length))
curr_key, key_score = simulated_annealing(score_key, get_neighbour_block_key, sentence, curr_key, 20)
key, score = simulated_annealing(score_sentence, get_neighbour_block_key, sentence, curr_key, 0.1)
if best_score is None or score > best_score:
best_score = score
best_key = key
print("best score (annealing): {}".format(best_score))
# print("best score: {}".format(max(max(arr) for arr in arrays)))
print("best key: {}".format(best_key))
print(part1.encryptBlock(sentence, list(best_key), False))
return " ".join([" ".join((str(k) for k in best_key)), "|", part1.encryptBlock(orig_sentence, best_key, False)])
def score_sentence(key, scores_dp, sentence):
# if this score has already been calculated, just return it
if key in scores_dp:
return scores_dp[key]
# else, calculate the score and return it
dcr_sentence = part1.encryptBlock(sentence, key, False) # from part 1
return part2.get_ptb_sentence_score(dcr_sentence, ptb_prob_weights) # from part 2
def crack3a(ciphertext):
bestScore = -inf
bestText = None
bestKey = -1
for i in range(0, 26):
newText = part1.encryptBlock(ciphertext, [i], False)
newScore = part2.get_ptb_sentence_score(part2.sanitize_input(newText), ptb_prob_weights)
if newScore > bestScore:
bestScore = newScore
bestText = newText
bestKey = i
return str(bestKey) + " | " + bestText
def crack3c(orig_sentence):
sentence = part2.sanitize_input(orig_sentence)
best_key = None
best_score = None
for key_length in range(1, 8):
for seed in range(3):
random.seed(seed)
curr_key = tuple(random.randint(0, 26) for _ in range(key_length))
curr_key, key_score = simulated_annealing(score_key, get_neighbour_block_key, sentence, curr_key, 20,
MAX_STEPS / 3)
key, score = simulated_annealing(score_sentence, get_neighbour_block_key, sentence, curr_key, 0.1,
MAX_STEPS / 3)
if best_score is None or score > best_score:
best_score = score
best_key = key
print("best score (annealing): {}".format(best_score))
# print("best score: {}".format(max(max(arr) for arr in arrays)))
print("best key: {}".format(best_key))
print(part1.encryptBlock(sentence, list(best_key), False))
return " ".join([" ".join((str(k) for k in best_key)), "|", part1.encryptBlock(orig_sentence, best_key, False)])
def simulated_annealing(get_score, get_neighbour, sentence, curr_key, score_scale, max_steps=MAX_STEPS):
temperature = MAX_TEMPERATURE
# track score over time
scores_dp = OrderedDict()
# keep the best resolution for printing at the end
best_score = get_score(curr_key, scores_dp, sentence)
best_key = curr_key
best_decrypt = part1.encryptBlock(sentence, list(best_key), False)
step = 0
while step < max_steps:
# score current state (only care about maximum per location)
curr_score = get_score(curr_key, scores_dp, sentence)
# track score
scores_dp[curr_key] = curr_score
# print(temperature, curr_score)
# pick random neighbour
new_key = get_neighbour(curr_key, isStateValid)
new_score = get_score(new_key, scores_dp, sentence)
# export for visualization
# print("{}|{}|{}".format(time.time(), best_score, best_decrypt), file=VISUALIZATION_FILE)
if pick_state(curr_score, new_score, temperature, MAX_TEMPERATURE, BASE_SELECTIVITY,
score_scale) > random.random():
curr_key = new_key
if new_score > best_score:
best_score = new_score
best_key = new_key
# print("step {} \tbest {}".format(step, best_score))
temperature = anneal(temperature, step)
step += 1
return best_key, best_score