#python program to solve a null cipher.
#by searching letter patterns
# This program outputs all trial decrypts 
#that contain the crib.
# Assume ciphertext has no punctuation
print "Search null cipher for crib matches."
filename = raw_input("Enter filename: ")
f1 = open(filename)
codetext = f1.read()
f1.close
print codetext
codetext= codetext.lower()
crib = raw_input("Enter crib: ")
crib = crib.lower()
code = codetext.split()
lens = [len(w) for w in code]
max_len = max(lens)
print "Maximum word length is ",max_len
kl = raw_input("Enter pattern length: ")
key_len = int(kl)
me="count from (F)irst or (L)ast letter: "
di = raw_input(me)
if di.upper()[0] == 'L':
	dx = 1
else:
	dx = 0
				
key = [0]*key_len

def get_plain():
	index = 0
	plain = ''
	for w in code:
		n = key[index]
		if n>= len(w): return ' '
		if dx :
			plain += w[-n-1]
		else: plain += w[n]
		index += 1
		if index == key_len:
			index = 0
	return plain

def make_key(index):
	if index == key_len-1:
		for k in range(max_len):
			key[index] = k
			plain = get_plain()
			if plain.find(crib) > -1 :
				print plain, key
	else:
		for k in range(max_len):
			key[index] = k
			make_key(index+1)
	
make_key(0)