import string
key = 3


def decode(text):
    print "key:", key
    enc = ""
    columnlen = len(text) // key
    if len(text) % key != 0:
        columnlen += 1
        
    print "Textlänge:", len(text)
    print "Zeilen:", columnlen  
    
    for k in range (columnlen):
        for n in range(1+ (len(text) // columnlen)):  
            i =  k + (columnlen * n)
            if i < len(text):          
                ch = text[i]
            else:
                ch = ""
            enc += ch                 
          
    return enc

fInp = open("secret.txt")
text = fInp.read()
fInp.close() 

print "Krypto:\n", text
krypto = decode(text)
print "Message:\n", krypto

fOut = open("message.txt", "w")    
for ch in krypto:
    fOut.write(ch)
fOut.close()