Cryptography was being used by the few who cared. We could encrypt our e-mail with PCP, but mostly we didn't. We could encrypt sensitive files, but mostly we didn't. I don't remember having the option of a usable full-disk encryption product, at least one that I would trust to be reliable. What we did have were ideas-research and engineering ideas-and that was the point of Applied Cryptography. My goal in writing the book was to collect all the good ideas of academic cryptography under one cover and in a form that non-mathematicians could read and use.