Cryptography Challenge

As a part of my project for COMP 4951 A (Cryptography) at Mount Allison, I have been involved in designing a symmetric key block cipher. My cipher features a variable blocksize (16, 32, 64, or 128 bits), a variable key size (1, 2, or 4 times the blocksize), and a variable number of rounds (from 1 to 256). As a challenge to the rest of the CS 4951 class, I've decided to put a number of ciphers up here, with rewards going to the first person to either a) determine the plaintext of a given cipher (and the key used to encrypt the plaintext), or b) find a systematic weakness in the cipher algorithm I'm employing. In this case, a systematic weakness is one which is present at any block or key size (thus telling me that the 16-bit block size opens the cipher up to traffic analysis is not a systematic weakness, the ease of exhaustively searching a 16-bit keyspace is not a systematic weakness, but a vulnerability to differential cryptanalysis, even if only for certain keys, would be).

Ciphers placed on this page will be identified by their blocksize, keysize, and the number of rounds used (all expressed in hexadecimal). So, for example, 2X2XA.uu would be a uu-encoded .tar.gz archive containing the ciphertext of a cipher with a 2-octet block size (16 bits), a 2-octet key size (16 bits) and a 10-round encryption.

The algorithmic description of my cipher is located here.

For those who don't want to try coding their own, a set of C++ classes which can be combined with CryptoPP 5.0 can be found here.

Below are the current challenges. I'll add more as I encode them. Note that, to make things easy, the plaintext will always be ASCII text, and recognizable English at that.

The contest will remain open indefinitely.

This contest is open to everyone, but prizes will no longer be awarded except in the case of very innovative solutions.

Page last updated February 26, 2008

All content on this page, including downloadable content, is © 2001-2008 by Brian York.

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