# Attack on Tiny Encryption Algorithm (TEA)
### by Vince Belanger


CPS 472 - Computer & Network Security

Assignment 1

February 12, 2019

University of Dayton - Dr. Yao

The assignment contains four files, although only two are required to run.

encrypt.py - Generates 100 lines of random 64-bit 1-5 digit plaintexts, with
their corresponding TEA-encrypted ciphertexts. Writes to a file called
message-pairs and will create the file if no such file exists. When run, the
program will take your input for K0 and K1 of the key.

attack.py - Reads inputs in the format of two blocks of plaintext separated
by a space, then two blocks of corresponding ciphertext separated by space.
The plaintext and ciphertext are separated by a tab. Each line is expected
to be one pair of plaintext/ciphertext. The program reads in the lines to a
list, then it takes the first line and guesses a K0 value. It calculates the
K1 value based on that, then tests other plaintext/ciphertext pairs to see
if the K1 values match up. If they match up after 12 consecutive successes,
the K0 and K1 values are deemed to be the correct key values! If not, K0
increments until the correct values are found.

specified_encrypt.py - A variant of encrypt.py, it performs TEA encryption
on hard-coded plaintext and key values. I used this for testing purposes.

message-pairs - A file of plaintexts and ciphertexts, containing the values
I most recently generated using encrypt.py before submitting

To run the program, make sure encrypt.py and attack.py are in the same
directory. Then, run encrypt.py just like you would any other Python file,
in order to generate a new message-pairs file. The program will take your
input for K0 and K1 of the key. Then run attack.py and watch the magic.