I'm not too sure what specific field of cryptography he's particularly interested in, but I do know that he likes clever algorithms that make sense when you think about it.
How about some of the following:
- "Real-World Cryptography" is my recommendation for the first book to read, but probably won't work for your friend as it doesn't cover any algorithms in detail. It's a great topic to cover a lot of ground quickly to gain a good understanding of how cryptography is used in practice.
- "Introduction to Modern Cryptography" is used as a textbook on many universities and I recommend it for someone who doesn't mind diving in into the maths. Being a textbook, it's fairly academic.
- "The Code Book: The Secret History of Codes and Code-breaking" covers the history.
- For TLS and PKI, read "Bulletproof TLS and PKI" (disclaimer: I wrote it). It's a good book to understand practical protocol engineering in the context of the evolution of TLS from 1995 until now.
Edits:
- The manga book is very nice and fun, but high level and dated.
- Crypto by Steven Levy also recommended.
- Serious Cryptography is good, but Real-World Cryptography is more recent and provides a better foundation.
- Cryptography Engineering / Practical Cryptography / Applied Cryptography are often recommended, but they're very dated at this point.
- Your friend might enjoy https://cryptopals.com/
Note that there’s a big math gap between AES and, eg, implementing ed25519. But if he likes this stuff, HEHCC will be a new joy every day.
You can also find the pdf online, since it’s pretty expensive and you want to make a gift, maybe you can get the Singh and throw this pdf in as a bonus challenge :)
https://www.amazon.com/Manga-Guide-Cryptography-Guides/dp/15...