回信加密

Posted 2021-02-27

simple encryption program written just for fun.

Usage:
$ python letterback.py -e "alvin"
zkuhm
$ python letterback.py -d "zkuhm"
alvin

Or in the python interpreter.

In [1]: import letterback
In [2]: lb = letterback.LetterBack()
In [3]: lb.encrypt("alvin")
zkuhm
In [4]: lb.decrypt("zkuhm")
alvin

import sys
 
alphabet = 'abcdefghijklmnopqrstuvwxyz'
 
class LetterBack:
    '''Class for Encrypting a string of letters'''
 
    def __init__(self, text='mnm'):
        self.text = text
 
    def encrypt(self, aSentance):
        '''Encrypts a given string by replacing each letter
        with the letter before it in the alphabet.'''
        output = ''
        for element in aSentance:
            for i in range(26):
                if element == alphabet[i]:
                    output += alphabet[i-1]
        print output
 
    def decrypt(self, aSentance):
        '''Decrypts a given string encoded by the encrypt
         function.'''
        output = ''
        for element in aSentance:
            #print element + ' this is 1'
            for i in range(26):
                if element == alphabet[i-1]:
                    output += alphabet[i]
        print output
 
def main():
    lb = LetterBack()
    if sys.argv[1] == '-e':
        lb.encrypt(sys.argv[2])
    elif sys.argv[1] == '-d':
        lb.decrypt(sys.argv[2])
 
if __name__ == '__main__':
    main()