Boaz Barak Mohammad Mahmoody-Ghidary Merkle Puzzles Are Optimal - An <i>O</i>(<i>n</i><sup>2</sup>)-Query Attack on Any Key Exchange from a Random Oracle. 374-390 2009 CRYPTO http://dx.doi.org/10.1007/978-3-642-03356-8_22 conf/crypto/2009 db/conf/crypto/crypto2009.html#BarakM09