3 Round DES
This is an implementation of DES weakened till the point of crackability. Specifically:
We are using only 3 rounds, using subkeys 1, 2 and 3 only;
We are not using the Initial or Final Permutations;
Using Differentail Cryptanalysis easily cracks this version of DES, as is explained in:
Cryptography: Theory and Practice,
Douglas R. Stinson, CRC Press.
Compared to the discussion in this text, we do swap left and right 32 bits, in order to maintain decryption/encryption symmetry.
Enter a 16-hexadecimal digit to encode with the secret key:
Notes:
This page is intended for students of MTH 609.
Code used is highly modified from the original RSAREF.
This is a very weak cryptosystem for a chosen plaintext attack.
See the
C code
and
Header file
for more details.
Additional class notes, in postscript,
Notes on
Modular Arithmetic
Notes on
basic Abstract Algebra
Notes on Primality Testing using the
Jacobi Symbol.
Notes on factoring using the
Factor Base Algorithms.