4-bit Block Cipher

""" Scratch file for Crypto.io """

plaintext_space = "0123456789ABCDEF"
key = {'0': 'F', '1': '2', '2': '7', '3': '4',
       '4': '5', '5': 'C', '6': '9', '7': 'E',
       '8': 'D', '9': '1', 'A': '3', 'B': '6',
       'C': '3', 'D': 'A', 'E': 'B', 'F': '0'}

def main():
    plaintext = "12B70ADE"
    cryptotext = encrypt(key, plaintext)
    othertext = decrypt(key, cryptotext)
    print(othertext)

def encrypt(k, P):
    return ''.join([key[p] for p in P])

def decrypt(k, C):
    reverse_key = {k[val]: val for val in k}
    return ''.join(reverse_key[c] for c in C)

if __name__ == "__main__":
    main()