Context
Stream ciphers are used for encryption on devices with low computational power or where time-sensitive encryption is required. Examples of stream ciphers include A5/1, which is used in the Global System for Mobile Communications (GSM™) for cellphone communications and E0, the stream cipher used in the Bluetooth® protocol.
A diagram of stream cipher encryption: the key, K, is used to encrypt the plaintext message, P, by expanding the key into the keystream and then combining it with the plaintext to produce the ciphertext, C. Decryption is similar, except that the ciphertext is combined with the keystream to produce the plaintext.
Project
This project implements a cryptanalysis technique called a fast correlation attack that works on certain stream ciphers. The implementation is tested against a stream cipher component called the Geffe keystream generator. Success of the technique is demonstrated on specified ranges of parameters. The report detailing the work done is available in the Downloads section.
The project was submitted as part of the requirements for a BSc Honours in Mathematics of Computer Science at the University of Cape Town.
Supervisors
Dr Anne Kayem (Department of Computer Science)
Dr Christine Swart (Department of Mathematics and Applied Mathematics)