Basic transposition cracker. Added method to check for THE in text (quicker than scouring the dictionary). Added method to strip \r \n chars from the output.

exercise5.py

#!/usr/bin/env python

import math

def getStrings(file1):
	"Get the string from the file"
	with open(file1, 'r') as a:
		b = a.readlines()
	return (''.join(b))

def decrypt(x, y):
	"""x = key
	y = message
	Get num of columns from key"""
	numColumns = int(math.ceil(len(y) / x))
	whiteSpace = (numColumns * x) - len(y) #White space at end of table
	text = [''] * (numColumns + 1) #Create array correct size
	col = 0
	row = 0
	for c in y:
		"Loop over characters (c) in y. Add to array at index[column]"
		text[col] += c
		col = int(col + 1 % numColumns)
				
		if (col == int(numColumns)) or ((col == numColumns - 1) and (row >= x - whiteSpace)):
			"""If column exceeds correct value, start again."""
			col = 0
			row += 1

	solution = ''.join(text).strip('\n') #Remove stray newline that appears for some reason

	return solution

if __name__ == '__main__':
	file1 = raw_input("Enter file with cipher text: ")
	y = getStrings(file1)


	for x in range(4, 9, 1):
		"""Loop between 4-8 to find the solution"""
		solution = decrypt(int(x), y)

		#Likely to contain THE. 
		if "THE" in solution:

			print (int(x))
			print (solution.strip('\r'))
		#Another attempt to remove god damn new line char