Talk
An investigation on the Roos’s biases after the RC4 Key Scheduling Algorithm
Talk by Alessandro Verzasconi
Date: 07.03.18 Time: 16.00 - 17.00 Room: Y27H28
RC4 was firstly described in 1987 by Ron Rivest and it is nowadays one of the most popular stream ciphers, with important applications in the encryption protocols such as WEP and WPA.
In 1995 Andrew Roos observed, that the bytes SN[y] of the permutation obtained after the Key Scheduling Algorithm for small values of y, are biased toward the secret key. An explanation of this bias was given in 2007 by Paul and Maitra and was revisited in 2017 by Sarkar and Venkatesvarlu. In the same work they improve a result discovered in 2008 by Paul and Maitra, which explains the bias between the nested entries of SN and the secret key.
We explain in details the differences between these results, giving a practical application on how to use this bias to recover the secret key after the Key Scheduling Algorithm.