def d_substitution(ciphertext, key):
plaintext = ""
alphabet = utilities.adjust_key(utilities.get_baseString())
#key = key
#alphabet = utilities.adjust_key(alphabet)
#print(alphabet)
#print(key)
for cipherChar in ciphertext:
if (cipherChar.isupper()):
upperFlag = True
else:
upperFlag = False
cipherChar = cipherChar.lower()
if cipherChar in alphabet:
indx = key.index(cipherChar)
plainChar = alphabet[indx]
plainChar = plainChar.upper() if upperFlag else plainChar
else:
if (upperFlag == True):
plainChar = cipherChar.upper()
else:
plainChar = cipherChar
plaintext += plainChar
#print(plaintext)
#plaintext = utilities.adjust_key(plaintext)
#print(utilities.adjust_key(plaintext))
return plaintext
def e_substitution(plaintext, key):
# your code here
subString = key
subString = utilities.adjust_key(subString)
baseString = utilities.get_baseString()
baseString = utilities.adjust_key(baseString)
ciphertext = ''
for plainChar in plaintext:
#if(plainChar == 'Ã'):
#print(plainChar.isupper())
if (plainChar.isupper()):
upperFlag = True
else:
upperFlag = False
plainChar = plainChar.lower()
if plainChar in baseString:
indx = baseString.index(plainChar)
cipherChar = subString[indx]
cipherChar = cipherChar.upper() if upperFlag else cipherChar
else:
if (upperFlag == True):
cipherChar = plainChar.upper()
else:
cipherChar = plainChar
ciphertext += cipherChar
#print(ciphertext)
ciphertext = utilities.adjust_key(ciphertext)
return ciphertext
def d_substitution(ciphertext,key):
# your code here
plaintext = ''
alphabet = utilities.adjust_key(utilities.get_baseString())
for cipherChar in ciphertext:
upperFlag = True if cipherChar.isupper() else False
cipherChar = cipherChar.lower()
if cipherChar in alphabet:
indx = key.index(cipherChar)
plainChar = alphabet[indx]
plainChar = plainChar.upper() if upperFlag else plainChar
else:
plainChar = cipherChar.upper() if upperFlag else cipherChar
plaintext+= plainChar
return plaintext
def e_substitution(plaintext,key):
baseString = utilities.adjust_key(utilities.get_baseString())
subString = utilities.adjust_key(key)
ciphertext = ''
for plainChar in plaintext:
upperFlag = True if plainChar.isupper() else False
plainChar = plainChar.lower()
if plainChar in baseString:
indx = baseString.index(plainChar)
cipherChar = subString[indx]
cipherChar = cipherChar.upper() if upperFlag else cipherChar
else:
cipherChar = plainChar.upper() if upperFlag else plainChar
ciphertext += cipherChar
# if('#' in ciphertext):
ciphertext = utilities.adjust_key(ciphertext)
return ciphertext
def cryptanalysis_mathCipher(ciphertext):
# your code here
baseString = utilities.get_baseString()
length = len(baseString)
dictList = utilities.load_dictionary('engmix.txt')
sub_baseString = []
for j in range(25, length):
sub_baseString.append(baseString[:j + 1])
attempts = 0
for n_s in sub_baseString:
m = len(n_s)
m_i_table = mod.mul_inv_table(m)
for mi1 in m_i_table[0]:
if m_i_table[1][mi1] != 'NA':
for mi2 in m_i_table[0]:
if m_i_table[1][mi2] != 'NA':
for c in range(m):
if mod.residue(mi2**2 - c, m) != 0:
k = [mi1, mi2, c]
key = (n_s, k)
plaintext = d_mathCipher(ciphertext, key)
attempts += 1
if len(utilities.remove_nonalpha(
plaintext)) < len(plaintext) / 2:
continue
if utilities.is_plaintext(
plaintext, dictList, 0.90):
print('key found after ' + str(attempts) +
' attempts')
return plaintext, key
return '', ''
def d_substitution(ciphertext, key):
# your code here
plaintext = ''
ciphertext = ciphertext.replace('\n', '#')
key = utilities.adjust_key(key)
baseString = utilities.get_baseString()
for cipherChar in ciphertext:
upperFlag = True if cipherChar.isupper() else False
cipherChar = cipherChar.lower()
if cipherChar in key:
Index = key.index(cipherChar)
plainChar = baseString[Index]
plainChar = plainChar.upper() if upperFlag else plainChar
else:
plainChar = cipherChar.upper() if upperFlag else cipherChar
plaintext += plainChar
plaintext = plaintext.replace('#', '\n')
return plaintext
def e_substitution(plaintext, key):
# your code here
ciphertext = ''
plaintext = plaintext.replace('\n', '#')
key = utilities.adjust_key(key)
baseString = utilities.get_baseString()
for plainChar in plaintext:
upperFlag = True if plainChar.isupper() else False
plainChar = plainChar.lower()
if plainChar in baseString:
Index = baseString.index(plainChar)
cipherChar = key[Index]
cipherChar = cipherChar.upper() if upperFlag else cipherChar
else:
cipherChar = plainChar.upper() if upperFlag else plainChar
ciphertext += cipherChar
ciphertext = ciphertext.replace('#', '\n')
return ciphertext
def test_q1():
print("-------------------------------------------")
print("Testing Q1: MathCipher")
print()
alphabet = utilities.get_lower()
print('Testing validity of keys:')
keys = [['ab', [1, 1, 1]], ('', [1, 1, 1]), ('a', [1, 1, 1]),
(123, [1, 1, 1]), ('ab', (1, 1, 1)), ('ab', [1, 1]),
('ab', [1, '1', 1]), (alphabet, [6, 7, 11]),
(alphabet, [11, 13, 19]), (alphabet, [11, 7, 13])]
for key in keys:
print(key, ' = ', final.isValidKey_mathCipher(key))
print()
print('Testing Encryption/Decryption:')
baseStr = alphabet
k = [5, 9, 11]
plaintext = 'MATH CIPHER'
key = (baseStr, k)
print('key = ', key)
print('plaintext = ', plaintext)
ciphertext = final.e_mathCipher(plaintext, key)
print('ciphertext= ', ciphertext)
plaintext2 = final.d_mathCipher(ciphertext, key)
print('plaintext2= ', plaintext2)
print()
baseStr = alphabet + ' ?!'
k = [45, 5, 16]
plaintext = 'Is mission accomplished?'
key = (baseStr, k)
print('key = ', key)
print('plaintext = ', plaintext)
ciphertext = final.e_mathCipher(plaintext, key)
print('ciphertext= ', ciphertext)
plaintext2 = final.d_mathCipher(ciphertext, key)
print('plaintext2= ', plaintext2)
print()
baseStr = alphabet + ' ?!#'
k = [5, 5, 5]
plaintext = ''
key = (baseStr, k)
print('key = ', key)
print('plaintext = ', plaintext)
ciphertext = final.e_mathCipher(plaintext, key)
print()
plaintext2 = final.d_mathCipher(ciphertext, key)
print()
print()
k = [421, 421, 421]
baseStr = alphabet + '?!'
key = (baseStr, k)
plaintext = 'The quick brown fox jumps over the lazy dog'
print('key = ', key)
print('plaintext = ', plaintext)
ciphertext = final.e_mathCipher(plaintext, key)
print('ciphertext= ', ciphertext)
plaintext2 = final.d_mathCipher(ciphertext, key)
print('plaintext2= ', plaintext2)
print()
k = [10, 3, 9]
baseStr = alphabet + '#?!'
key = (baseStr, k)
print('key = ', key)
print('plaintext = ', plaintext)
ciphertext = final.e_mathCipher(plaintext, key)
print('ciphertext= ', ciphertext)
plaintext2 = final.d_mathCipher(ciphertext, key)
print('plaintext2= ', plaintext2)
print()
k = [0, 1, 1]
plaintext = 'This is Q1 of CP460 Final Exam'
key = (baseStr, k)
print('key = ', key)
print('plaintext = ', plaintext)
ciphertext = final.e_mathCipher(plaintext, key)
print()
plaintext2 = final.d_mathCipher(plaintext, key)
print()
print()
print('Testing analyze_mathCipher:')
base = 'ab'
print('Analyze: ', base, '= ', final.analyze_mathCipher(base))
base = 'abc'
print('Analyze: ', base, '= ', final.analyze_mathCipher(base))
base = 'abcd'
print('Analyze: ', base, '= ', final.analyze_mathCipher(base))
base = 'abcde'
print('Analyze: ', base, '= ', final.analyze_mathCipher(base))
base = 'abcdefg'
print('Analyze: ', base, '= ', final.analyze_mathCipher(base))
base = utilities.get_lower()
print('Analyze: ', base, '= ', final.analyze_mathCipher(base))
base = base + '!#?'
print('Analyze: ', base, '= ', final.analyze_mathCipher(base))
print()
print('Testing stats_mathCipher:')
final.stats_mathCipher()
print()
print('Testing cryptanalysis:')
plaintext = 'There are two kinds of cryptography in this world: cryptography that will stop your kid sister '
plaintext += 'from reading your files, and cryptography that will stop major governments from reading your files.'
baseString = utilities.get_baseString()[:26]
key = (baseString, [3, 9, 11])
ciphertext = final.e_mathCipher(plaintext, key)
plaintext, key = final.cryptanalysis_mathCipher(ciphertext)
if plaintext != '':
print('Key = ', key)
print('plaintext = ', plaintext)
print()
ciphertext = 'Uxcnoicostplqpcampcaptaugec ktptcxolcamutcdiptauog,cnoicyurrcxughctozpcmugat'
print('ciphertext: ', ciphertext)
plaintext, key = final.cryptanalysis_mathCipher(ciphertext)
if plaintext != '':
print('Key = ', key)
print('plaintext = ', plaintext)
print()
print("-------------------------------------------")
return