# Crypto

## How the columns have turned - ex0244

### Decryption tool

#!/usr/bin/env python3

def blocks(width, txt):
    len_text = len(txt)
    block_size = int(len_text / width)
    return [txt[i:i + block_size] for i in range(0, len(txt), block_size)]

def redo(derived_key, blocks):
    return [blocks[int(derived_key[i])-1][::-1] for i in range(len(derived_key))]

def transpose(array):
    return [row for row in map(list, zip(*array))]

def flatten(array):
    return "".join([i for sub in array for i in sub])

if __name__ == '__main__':
    key = '729513912306026'
    derived_key = [13, 5, 14, 10, 3, 8, 15, 4, 6, 9, 1, 11, 2, 7, 12]
    width = len(key)

    with open('encrypted_messages.txt', 'r') as f:
        enc_text = [msg.strip() for msg in f.readlines()]
        for msg in enc_text:
            blocks_1 = blocks(width, msg)
            redo_1 = redo(derived_key, blocks_1)
            transp = transpose(redo_1)
            flatt = flatten(transp)
            print(flatt)