Choose crypto library

[ilblackdragon]

Most probably one that ethereum/parity uses. Options:

• Parity: https://github.com/rust-bitcoin/rust-secp256k1
• Solana: https://github.com/briansmith/ring, e.g. use ring::signature::Ed25519KeyPair;
• Exonum: https://github.com/exonum/exonum_sodiumoxide

[ilblackdragon]

Also which hashing function \ library we should use @david-stolp. I see ppl using Crate:

• sha2 - https://docs.rs/sha2/0.8.0/sha2/
• https://github.com/paritytech/keccak-hash

[ilblackdragon]

For now using exonum_sodiumoxide but isolate it in primitives in case we want to switch.