playf1.py

from string import ascii_uppercase
from itertools import product
from re import findall

mode = raw_input("Do you want to Encrypt or Decrypt ? ")
txt = raw_input("Please Enter Text: ")
key = raw_input("Please Enter Key")
def uniq(seq):
    seen = {}
    return [seen.setdefault(x, x) for x in seq if x not in seen]


def part(seq, n):
    return [seq[i: i + n] for i in xrange(0, len(seq), n)]

def playfair(key, from_='J', to=None):
    if to is None:
        to = 'I' if from_ == 'J' else ''

    def canonicalize(s):
        return filter(str.isupper, s.upper()).replace(from_, to)


    m = part(uniq(canonicalize(key + ascii_uppercase)), 5)

    enc = {}

    for row in m:
        for i, j in product(xrange(5), repeat=2):
            if i != j:
                enc[row[i] + row[j]] = row[(i + 1) % 5] + row[(j + 1) % 5]

    for c in zip(*m):
        for i, j in product(xrange(5), repeat=2):
            if i != j:
                enc[c[i] + c[j]] = c[(i + 1) % 5] + c[(j + 1) % 5]


    for i1, j1, i2, j2 in product(xrange(5), repeat=4):
        if i1 != i2 and j1 != j2:
            enc[m[i1][j1] + m[i2][j2]] = m[i1][j2] + m[i2][j1]

    dec = dict((v, k) for k, v in enc.iteritems())

    def sub_enc(txt):
        lst = findall(r"(.)(?:(?!\1)(.))?", canonicalize(txt))
        return " ".join(enc[a + (b if b else 'X')] for a, b in lst)

    def sub_dec(encoded):
        return " ".join(dec[p] for p in part(canonicalize(encoded), 2))

    return sub_enc, sub_dec


(encode, decode) = playfair(key)
print "Original:", txt

if mode == "encrypt":
    enc = encode(txt)
    print "Encoded:", enc
elif mode == "decrypt":
    print "Decoded:", decode(txt)