Public-key cryptography 2: El Gamal
Instead of using difficulty of factoring, we use difficulty of taking discrete logarithms.
- Pick modulus, subgrp generator (g)
- Secret keys (s) are random numbers; public keys (p) is g to the s.
- Encrypt message by picking blinding exponent (e), multiplying message by p^e. Also send g^e; recipient computes g^e^s (=p^e), and divides to recover message.