Add support for RustCrypto's crypto-bigint

[ycscaly]

Hey everyone,

Currently, there are two supported bigint libraries: GMP and num-bigint. However, there is another option that hasn't been discussed here: RustCrypto's crypto-bigint (repo, crate).

It is an official Rust crate that is constant-time and no-std pure Rust. I see much value in this crate and for me this would seem like the obvious default, unless there are some other considerations that you take into account, and if so please explain them.

Esp. for WASM support this makes a lot of sense.

Thanks!

[clarklee186]

sounds great.

[ycscaly]

Any feedback from maintaners?

[leontiadZen]

Hi @ycscaly thanks for suggesting that. We are in the process of next steps for making the lib constant time