Rivest describes the rc5 cipher here https://www.grc.com/r&d/rc5.pdf and includes a c reference implementation.
Further test cases can be found here https://datatracker.ietf.org/doc/html/draft-krovetz-rc6-rc5-vectors-00#section-4
cargo doc --open
cargo test
Fuzzing requires:
llvm-symbolizer- version 10- cargo fuzz
Run:
cargo fuzz run <name_of_fuzz_target>