The Tor Project replaces the Tor relay encryption with a new algorithm named the Counter Galois Onion

Counter Galois Onion: Improved encryption for Tor circuit traffic | Tor Project

Tor is upgrading its relay encryption algorithm for improved security. In upcoming releases, Arti and Tor will both support a new encryption algorithm called Counter Galois Onion (CGO). CGO prevents attackers from tampering with encrypted traffic, adds forward secrecy, and brings Tor's encryption up to modern standards.