Has anyone heard of this book [_Top_Secret_ - Data Encryption Techniques] and is it with the $19.95 that they want for it?
Only if you have a pressing and immediate need for a doorstop, or need special help solving the "Cryptoquotes" in your local paper.
If I'm not mixing it up with a similar book I saw in the store, I wouldn't be *quite* that negative; I'll comment on the two together. They're not academic books, and if you're using PGP there's not much you'll gain from them. The big weaknesses I saw were: - not mentioning that the techniques discussed are way outdated and easily broken by professionals (they tend to say this for the simpler methods, just not for the more complex ones.) - not discussing the *existence* of mathematical crypto techniques; it's ok not to go into details, depending on the scope of the book, but there should at least be pointers to the topics. One interesting feature of the books I looked at was that one of them came with a floppy disk with code on it. I didn't notice anything on the first few pages about "Not for export" or a mention that the government treats crypto as munitions that need special permits to export - I assume the authors are unaware of this, or that the NSA doesn't really care about this level of crypto any more than they care about rot-13 being exported :-) - but you'd think the publishers would notice.... Bill