Seokhie Hong Jongsung Kim Guil Kim Jaechul Sung Changhoon Lee Sangjin Lee Impossible Differential Attack on 30-Round SHACAL-2. 97-106 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=2904&spage=97 2003 conf/indocrypt/2003 INDOCRYPT db/conf/indocrypt/indocrypt2003.html#HongKKSLL03