Attacks on Encryption Schemes

∟Reference Citations in 2005

∟Attacks on Encryption Schemes

'CipherDES.java - A Java Implementation of DES' tutorial was cited in a BCS thesis at University of Liverpool in 2005.

The CipherDES.java - A Java Implementation of DES tutorial was cited in a BCS thesis at University of Liverpool in 2005. Note that my Geocities site has been moved to herongyang.com now.

Subject: Attacks on Encryption Schemes
Date: Mar 31, 2005
Source: University of Liverpool
Author: Benjamin Nickolls

Attacks on Encryption Schemes

Supervised by Dr Paul Sant

Honours project submitted to the Department of Computer Science for
BCS degree in (BSc) Computer Science.

Ownership of this report remains with the University of Liverpool.

Acknowledgements

I would like to acknowledge the support of Dr. Paul Sant throughout
the course of this study. His help and occasional prodding kept the
project moving in the face of all adversity.

I would also like to acknowledge the contribution made by Dr. Herong
Yang. Approval for the use of his copy written code enabled the
implementation of the Reduced-Block DES algorithm possible.

Abstract

In today's world of electronic communication secure transmission of
data is a necessity. This dissertation offers a critical appreciation
of modern day cryptosystems and the security that they can or can not
provide. A discussion of cryptography and cryptanalysis provides the
basis for a practical demonstration of two cryptanalytic attacks: An
implementation of the RSA public key system is used to illustrate an
attack developed by Michael Weiner exploiting a class of weak public
keys containing information on the corresponding decryption exponent.
This technique utilises the continued fraction algorithm operating in
O(n) time with respect the size of the modulus. A sixteen-bit,
private key, block cipher similar to that of the DEA is also presented
for the demonstration of a known plaintext, Brute- Force attack
executing a linear search of the key space operating in exponential
time O(2n) (where n is the bit-length of the key). Evaluation of this
software leads to a debate on the implications of future cryptography
and of computer security on a broader level.

Keywords: Cryptanalysis, DES, RSA, Weiner Attack, Brute-Force