Stéphane Flon Roger Oyono Fast Arithmetic on Jacobians of Picard Curves. 55-68 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2947&spage=55 2004 conf/pkc/2004 Public Key Cryptography db/conf/pkc/pkc2004.html#FlonO04