CryptoDB
Guglielmo Morgari
Affiliation: Telsy Elettronica e Telecomunicazioni
Publications
Year
Venue
Title
2008
EPRINT
Iterative Probabilistic Reconstruction of RC4 Internal States
Abstract
It is shown that an improved version of a previously proposed iterative probabilistic algorithm, based on forward and backward probability recursions along a short keystream segment, is capable of reconstructing the RC4 internal states from a relatively small number of known initial permutation entries. Given a modulus $N$, it is argued that about $N/3$ and $N/10$ known entries are sufficient for success, for consecutive and specially generated entries, respectively. The complexities of the corresponding guess-and-determine attacks are analyzed and, e.g., for $N=256$, the data and time complexities are (conservatively) estimated to be around $D \approx 2^{41}$, $C \approx 2^{689}$ and $D \approx 2^{211}$, $C \approx 2^{262}$, for the two types of guessed entries considered, respectively.
2004
EPRINT
Vectorial fast correlation attacks
Abstract
A new, vectorial approach to fast correlation attacks on binary memoryless combiners is proposed.
Instead of individual input sequences or their linear combinations, the new attack is targeting
subsets of input sequences as a whole, thus exploiting the full correlation between the chosen
subset and the output sequence. In particular, all the input sequences can be targeted simultaneously.
The attack is based on a novel iterative
probabilistic algorithm which is also applicable to general memoryless combiners over finite fields or finite
rings.
Experimental results obtained for randomly chosen binary combiners with balanced combining functions show
that the vectorial approach yields a considerable improvement in comparison with the classical, scalar approach.
Coauthors
- Vittorio Bagini (1)
- Jovan Dj. Golic (4)