Pgp: Source Code and Internals cover
Pgp: Source Code and Internals
by Philip R. Zimmermann
ISBN: 0262240394
Buy on Amazon
Found in 2 comments on Hacker News
daxelrod · 2016-11-30 · Original thread
I haven't read it, but "PGP: Source Code and Internals", by PGP's author Philip Zimmerman is worth a try. I've read his other book "Official PGP User's Guide" and learned quite a bit.

https://www.amazon.com/PGP-Internals-Philip-R-Zimmermann/dp/...

rdl · 2013-10-03 · Original thread
http://www.amazon.com/PGP-Internals-Philip-R-Zimmermann/dp/0...

http://www.pgpi.org/pgpi/project/scanning/