In 1996, Jenkins pointed out a correlation between the hidden state and the output keystream of RC4, which is well known as the Glimpse theorem. With a permutation of size N-bytes, the probability of guessing one location by random association is 1/N, whereas the existing correlations related to glimpse allow an adversary to guess a permutation location, using the knowledge of the keystream output bytes, with probability 2/N. To date, this is the best known state-leakage based on glimpse. For the first time in RC4 literature, we show that there are certain events that leak state information with a probability of 3/N, considerably higher than the existing results. Further, the new glimpse correlation that we observe is a long-term phenomenon; it remains valid at any stage of the evolution of RC4 Pseudo Random Generation Algorithm (PRGA). This new glimpse with a considerably higher probability of state-leakage may potentially have serious ramifications towards state-recovery attacks on RC4.
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