Cheating at Mental Poker

We review the “mental poker” scheme described by Shamir, Rivest and Adleman [SRA]. We present two possible means of cheating, depending on careless implementation of the SRA scheme. One will work if the prime p is such that p-1 has a small prime divisor. In the other scheme, the names of the cards “TWO OF CLUBS” have been extended by random-looking bits. chosen by the cheater.