Dima Ruinskiy Adi Shamir Boaz Tsaban Cryptanalysis of Group-Based Key Agreement Protocols Using Subgroup Distance Functions. 61-75 2007 conf/pkc/2007 Public Key Cryptography http://dx.doi.org/10.1007/978-3-540-71677-8_5 db/conf/pkc/pkc2007.html#RuinskiyST07