Rust CryptoPAn implementation

[mikemcdermottredjack]

Sorry to add this issue here, if that is wrong, but I don't see a better place for it.

We have an implementation of the CryptoPAn algorithm (primarily used for IP address anonymization) (https://en.wikipedia.org/wiki/Crypto-PAn) in Rust that we'd like to contribute to RustCrypto. There are no other Rust implementations of this algorithm that I could find (implementations exist for C++, GO, and Python).

We have demonstrably working code for IPv4 addresses. I'm happy to submit a PR under whichever repo is most appropriate (a new one might need to be created?)

Thanks

[newpavlov]

Hm, I think we can start with the utils repository. It's not the best fit, but I don't have better ideas right now. Later we may move it somewhere else.

[tarcieri]

This has an open PR at RustCrypto/formats#861