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playfair.py
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146 lines (131 loc) · 4.78 KB
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#!/usr/bin/env python
# -*- coding: utf-8 -*-
import sys
# @Author: Gleydson Rodrigues
# ./playfair.py [encrypt/decrypt] key message
alphabet = "abcdefghijlmnopqrstuvwxyz".upper()
def vetorize(text):
listText = []
for letter in text:
listText.append(letter)
return listText
def normalizeMessage(text):
newText = []
text = text.upper()
text = text.replace(" ", "")
text = text.replace(".", "")
text = text.replace(",", "")
pos = 0
while pos < len(text) - 1:
firstLetter = text[pos]
secondLetter = text[pos + 1]
if firstLetter == secondLetter:
if firstLetter == "X":
newText.append(firstLetter)
newText.append("Z")
pos += 1
else:
newText.append(firstLetter)
newText.append("X")
pos += 1
else:
newText.append(firstLetter)
newText.append(secondLetter)
pos += 2
if pos < len(text):
if text[-1] == "X":
newText.append(text[pos])
newText.append("Z")
else:
newText.append(text[pos])
newText.append("X")
return newText
def createMatrix():
matrix = []
for i in range(5):
matrix.append([])
for j in range(5):
matrix[i].append("")
return matrix
def mountGrid(matrix, key, alphabet):
alphabet = vetorize(alphabet)
line, column, pos = 0, 0, 0
for letter in key:
line = pos / 5
column = pos % 5
if letter in alphabet:
alphabet.remove(letter)
matrix[line][column] = letter
pos += 1
while len(alphabet) > 0:
line = pos / 5
column = pos % 5
matrix[line][column] = alphabet.pop(0)
pos += 1
return matrix
def getIndex(letter, matrix):
for i in range(5):
for j in range(5):
if matrix[i][j] == letter:
return [i, j]
def encrypt(message, key):
matrix = mountGrid(createMatrix(), key, alphabet)
message = normalizeMessage(message)
messageEncrypted = ""
pos, line, column = 0, 0, 1
while pos < len(message) - 1:
firstLetter = message[pos]
secondLetter = message[pos + 1]
indexFirstLetter = getIndex(firstLetter, matrix)
indexSecondLetter = getIndex(secondLetter, matrix)
if indexFirstLetter[line] == indexSecondLetter[line]:
messageEncrypted += matrix[indexFirstLetter[line]][(indexFirstLetter[column] + 1) % 5]
messageEncrypted += matrix[indexSecondLetter[line]][(indexSecondLetter[column] + 1) % 5]
elif indexFirstLetter[column] == indexSecondLetter[column]:
messageEncrypted += matrix[(indexFirstLetter[line] + 1) % 5][indexFirstLetter[column]]
messageEncrypted += matrix[(indexSecondLetter[line] + 1) % 5][indexSecondLetter[column]]
else:
messageEncrypted += matrix[indexFirstLetter[line]][indexSecondLetter[column]]
messageEncrypted += matrix[indexSecondLetter[line]][indexFirstLetter[column]]
pos += 2
return messageEncrypted
def decrypt(messageEncrypted, key):
matrix = mountGrid(createMatrix(), key, alphabet)
messageDecrypted = ""
pos, line, column = 0, 0, 1
while pos < len(messageEncrypted):
firstLetter = messageEncrypted[pos]
secondLetter = messageEncrypted[pos + 1]
indexFirstLetter = getIndex(firstLetter, matrix)
indexSecondLetter = getIndex(secondLetter, matrix)
if indexFirstLetter[line] == indexSecondLetter[line]:
messageDecrypted += matrix[indexFirstLetter[line]][(indexFirstLetter[column] - 1) % 5]
messageDecrypted += matrix[indexSecondLetter[line]][(indexSecondLetter[column] - 1) % 5]
elif indexFirstLetter[column] == indexSecondLetter[column]:
messageDecrypted += matrix[(indexFirstLetter[line] - 1) % 5][indexFirstLetter[column]]
messageDecrypted += matrix[(indexSecondLetter[line] - 1) % 5][indexSecondLetter[column]]
else:
messageDecrypted += matrix[indexFirstLetter[line]][indexSecondLetter[column]]
messageDecrypted += matrix[indexSecondLetter[line]][indexFirstLetter[column]]
pos += 2
return messageDecrypted
def help():
print(
"./playfair.py [encrypt/decrypt] key message"
)
def main():
params = sys.argv[1:]
if len(params) == 0:
help()
elif params[0] == "encrypt":
key = params[1].upper()
message = params[2:]
print(encrypt("".join(x for x in message).upper(), key))
elif params[0] == "decrypt":
key = params[1].upper()
message = params[2:]
print(decrypt("".join(x for x in message).upper(), key))
else:
help()
if __name__ == "__main__":
main()