Running to more than 360 pages, and complete with online files and updates, this book constitutes the thoroughly refereed post-proceedings of the 11th Asian Computing Science Conference, ASIAN 2006, held in Tokyo, Japan. The 17 revised full papers and 8 revised short papers presented together with 1 invited paper were carefully selected during two rounds of reviewing from 115 submissions. The papers cover theory, practice, applications, and experiences related to secure software.