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gowhari/vigenere-cipher.py

Created May 23, 2018 10:24
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  1. gowhari created this gist May 23, 2018.
    75 changes: 75 additions & 0 deletions vigenere-cipher.py
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,75 @@
    # encoding: utf8
    # vigenere cipher
    # https://stackoverflow.com/a/2490718/1675586

    def encode(key, string):
    encoded_chars = []
    for i in range(len(string)):
    key_c = key[i % len(key)]
    encoded_c = chr(ord(string[i]) + ord(key_c) % 256)
    encoded_chars.append(encoded_c)
    encoded_string = ''.join(encoded_chars)
    return encoded_string

    def decode(key, string):
    encoded_chars = []
    for i in range(len(string)):
    key_c = key[i % len(key)]
    encoded_c = chr((ord(string[i]) - ord(key_c) + 256) % 256)
    encoded_chars.append(encoded_c)
    encoded_string = ''.join(encoded_chars)
    return encoded_string

    e = encode('a key', 'a message')
    d = decode('a key', e)
    print([e])
    print([d])

    # python 3
    # ['Â@ØÊìÔ\x81ÒÊ']
    # ['a message']

    # python 2
    # ['\xc2@\xd8\xca\xec\xd4\x81\xd2\xca']
    # ['a message']


    #--------------------------------------------------
    # this version makes it also base64:


    import six, base64

    def encode(key, string):
    encoded_chars = []
    for i in range(len(string)):
    key_c = key[i % len(key)]
    encoded_c = chr(ord(string[i]) + ord(key_c) % 256)
    encoded_chars.append(encoded_c)
    encoded_string = ''.join(encoded_chars)
    encoded_string = encoded_string.encode('latin') if six.PY3 else encoded_string
    return base64.urlsafe_b64encode(encoded_string).rstrip(b'=')

    def decode(key, string):
    string = base64.urlsafe_b64decode(string + b'===')
    string = string.decode('latin') if six.PY3 else string
    encoded_chars = []
    for i in range(len(string)):
    key_c = key[i % len(key)]
    encoded_c = chr((ord(string[i]) - ord(key_c) + 256) % 256)
    encoded_chars.append(encoded_c)
    encoded_string = ''.join(encoded_chars)
    return encoded_string

    e = encode('a key', 'a message')
    d = decode('a key', e)
    print([e])
    print([d])

    # python 3
    # [b'wkDYyuzUgdLK']
    # ['a message']

    # python 2
    # ['wkDYyuzUgdLK']
    # ['a message']