Are there any Cryptography Algorithms that involve Lots of Number Theory? I am looking for a good, meaty cryptography algorithm that involves a good amount of number theory in which I can explore. I'm researching, and AES (Advanced Encryption System) seems interesting, but does not really seem to involve number theory all that much.
EDIT: Not RSA.
The Falcon digital signature algorithm is as &quot;meaty&quot; as one can be.

It has an NTRU-like key generation procedure and public key lattice structure;

its security is based on conjectured difficulty of lattice reduction in classical and quantum computers;

its efficiency is based on number-theoretic transformation and fast discrete normal distribution sampling;

its compactness is based on entropy coding.


Some more to be listed.