def find_best_key(key, cipherText):
'''
finds the best scoring key by modifying the key one letter at a time and calculating the log score
:param key:
:param cipherText:
:return:
'''
bestKey = key
bestScore = float(calculate_log_score(Vignere.decrypt(cipherText, key), 4))
score = -1
for index in range(0, len(key)):
for letter in range(0, 26):
key = iterate_key(key, index, letter)
score = float(calculate_log_score(Vignere.decrypt(cipherText, key), 4))
if score > bestScore:
bestScore = score
bestKey = key
print ("%s\t%s\t%s" % (key, score, Vignere.decrypt(cipherText,key)))
key = bestKey
return bestKey
def find_best_key(key, cipherText):
'''
finds the best scoring key by modifying the key one letter at a time and calculating the log score
:param key:
:param cipherText:
:return:
'''
bestKey = key
bestScore = float(calculate_log_score(Vignere.decrypt(cipherText, key), 4))
score = -1
for index in range(0, len(key)):
for letter in range(0, 26):
key = iterate_key(key, index, letter)
score = float(
calculate_log_score(Vignere.decrypt(cipherText, key), 4))
if score > bestScore:
bestScore = score
bestKey = key
print("%s\t%s\t%s" %
(key, score, Vignere.decrypt(cipherText, key)))
key = bestKey
return bestKey
__author__ = 'jon-bassi'
import sys
import IndexOfCoincidence
import Vignere
import ChiSquaredStatistic
if len(sys.argv) != 2:
print 'error executing HW1_1.py\nusage: python HW1_1.py [text]'
sys.exit(0)
# find ic of different periods, target is > 0.06
# cipher text is hogvkiougtbtwlittwkopovsvebsvkiougtbtwlittwkjbd
# vptnvffuntshtarptymjwzirappljmhhqvsubwlzzygvtyitarptyiougxiuydtgzhhvvmumshwkzgstfmekvmpkswdgbilvjljmglmjfqwioiivknulvvfemioiemojtywdsajtwmtcgluysdsumfbieugmvalvxkjduetukatymvkqzhvqvgvptytjwwldyeevquhlulwpkt
text = sys.argv[1].lower()
IndexOfCoincidence.list_all_ic(text)
keyLength = int(raw_input('key length: '))
periodicList = [''] * keyLength
for idx in range(len(text)):
periodicList[idx % keyLength] += text[idx]
key = ''
for string in periodicList:
key += ChiSquaredStatistic.list_all_cs(string)
print ('key: %s\ndecrypted text: %s' % (key, Vignere.decrypt(text, key)))
score = float(
calculate_log_score(Vignere.decrypt(cipherText, key), 4))
if score > bestScore:
bestScore = score
bestKey = key
print("%s\t%s\t%s" %
(key, score, Vignere.decrypt(cipherText, key)))
key = bestKey
return bestKey
if __name__ == "__main__":
if len(sys.argv) != 3:
print 'error executing NGramScore.py\nusage: python NGramScore.py [text] [key size]'
sys.exit(0)
text = sys.argv[1]
keySize = int(sys.argv[2])
key = ''
# could make this a random key
for i in range(0, keySize):
key += 'a'
while True:
bestKey = find_best_key(key, text)
print('%s %s' % (bestKey, Vignere.decrypt(text, bestKey)))
input = raw_input('press enter to try again or type x to exit: ')
if input == 'x':
break
key = bestKey
for index in range(0, len(key)):
for letter in range(0, 26):
key = iterate_key(key, index, letter)
score = float(calculate_log_score(Vignere.decrypt(cipherText, key), 4))
if score > bestScore:
bestScore = score
bestKey = key
print ("%s\t%s\t%s" % (key, score, Vignere.decrypt(cipherText,key)))
key = bestKey
return bestKey
if __name__ == "__main__":
if len(sys.argv) != 3:
print 'error executing NGramScore.py\nusage: python NGramScore.py [text] [key size]'
sys.exit(0)
text = sys.argv[1]
keySize = int(sys.argv[2])
key = ''
# could make this a random key
for i in range(0, keySize):
key += 'a'
while True:
bestKey = find_best_key(key, text)
print('%s %s' % (bestKey, Vignere.decrypt(text, bestKey)))
input = raw_input('press enter to try again or type x to exit: ')
if input == 'x':
break
key = bestKey
__author__ = 'jon-bassi'
import sys
import IndexOfCoincidence
import Vignere
import ChiSquaredStatistic
if len(sys.argv) != 2:
print 'error executing HW1_1.py\nusage: python HW1_1.py [text]'
sys.exit(0)
# find ic of different periods, target is > 0.06
# cipher text is hogvkiougtbtwlittwkopovsvebsvkiougtbtwlittwkjbd
# vptnvffuntshtarptymjwzirappljmhhqvsubwlzzygvtyitarptyiougxiuydtgzhhvvmumshwkzgstfmekvmpkswdgbilvjljmglmjfqwioiivknulvvfemioiemojtywdsajtwmtcgluysdsumfbieugmvalvxkjduetukatymvkqzhvqvgvptytjwwldyeevquhlulwpkt
text = sys.argv[1].lower()
IndexOfCoincidence.list_all_ic(text)
keyLength = int(raw_input('key length: '))
periodicList = [''] * keyLength
for idx in range(len(text)):
periodicList[idx % keyLength] += text[idx]
key = ''
for string in periodicList:
key += ChiSquaredStatistic.list_all_cs(string)
print('key: %s\ndecrypted text: %s' % (key, Vignere.decrypt(text, key)))
