Cryptovirology: The Birth, Neglect, and Explosion of Ransomware
cacm.acm.org
cacm.acm.org
If I recall correctly they've also written some of a newer book too.
Edit: http://www.cryptovirology.com/ and click on 'new book' has some chapters
1. put together hacker and cryptographer
2. ????
3. profit.
I'm no cryptographer, but I know by rule-of-thumb that AES with a randomly-generated key will do the job just fine.