class Affine(Cipher):
"""Implements cipher via the affine method"""
def __init__(self, key, alphabet_size):
super().__init__("Affine", alphabet_size, key)
mkey, ckey = key
self.multiplication = Multiplication(mkey, alphabet_size)
self.caesar = Caesar(ckey, alphabet_size)
def encode(self, message):
caesared = self.caesar.encode(message)
multiplied = self.multiplication.encode(caesared)
return multiplied
def decode(self, encrypted):
multiplied = self.multiplication.decode(encrypted)
caesared = self.caesar.decode(multiplied)
return caesared
def candidate_keys(self):
caesar_candidates = self.caesar.candidate_keys()
multiplication_candidates = self.multiplication.candidate_keys()
return product(multiplication_candidates, caesar_candidates)
@staticmethod
def generate_key(alphabet_size):
return Multiplication.generate_key(alphabet_size), Caesar.generate_key(
alphabet_size)
def decode_chi(cipher):
d2 = {}
arr = []
for j in range(26):
k = (26-j)%26
temp = Caesar.decode(cipher,j)
sum = FrequencyAnalyzer.chisquaredstatistic(temp)
d2[k] = sum
return sort_dict_by_values(d2)[:3]
def run(params): function, infile, outfile, key = parser(params) if(function==0): return help() else: cypher = Caesar(key,infile,outfile) # initialize object cypher.encode() if(function==1) else cypher.decode()
class Affine:
""" Affine cipher """
def __init__(self):
self.caesar = Caesar()
self.multiplication = Multiplication()
def generate_keys(self):
""" Generates encryption and decryption key """
multiplication_encrypt, multiplication_decrypt = self.multiplication.generate_keys(
)
caesar_encrypt, caesar_decrypt = self.caesar.generate_keys()
encryption_key = (multiplication_encrypt, caesar_encrypt) # (48, 90)
decryption_key = (multiplication_decrypt, caesar_decrypt) # (2, 5)
return encryption_key, decryption_key
def encode(self, message, key):
""" Encode message with given key """
multiplication_key = key[0]
caesar_key = key[1]
# Encode with Multiplication then Caesar
partially_encoded = self.multiplication.encode(message,
multiplication_key)
encoded_message = self.caesar.encode(partially_encoded, caesar_key)
return encoded_message
def decode(self, encoded_message, decryption_keys):
""" Decode the encoded message with the decryption key """
multiplication_key = decryption_keys[0]
caesar_key = decryption_keys[1]
# Decode with Caesar then Multiplication
partially_decoded = self.caesar.decode(encoded_message, caesar_key)
decoded_message = self.multiplication.decode(partially_decoded,
multiplication_key)
return decoded_message
def decode(self, cypher_text, receivers_key):
caesar = Caesar()
multiplicative = Multiplicative()
multiplicative_cyphered = caesar.decode(cypher_text, receivers_key[1])
plain_text = multiplicative.decode(multiplicative_cyphered, receivers_key[0])
return plain_text
