Add docs and clarifications to verify_g1/verify_g2

Author: webmaster128

contracts/crypto-verify/src/bls12_381.rs

@@ -1,25 +1,34 @@
 use cosmwasm_std::{Api, HashFunction, StdResult, BLS12_381_G1_GENERATOR, BLS12_381_G2_GENERATOR};
 
+/// Signature verification with public key in G1 (e.g. drand classic mainnet, ETH2 block headers).
+///
+/// See https://hackmd.io/@benjaminion/bls12-381#Verification.
 pub fn verify_g1(
     api: &dyn Api,
     signature: &[u8],
     pubkey: &[u8],
     msg: &[u8],
     dst: &[u8],
 ) -> StdResult<bool> {
-    let s = api.bls12_381_hash_to_g2(HashFunction::Sha256, msg, dst)?;
-    api.bls12_381_pairing_equality(&BLS12_381_G1_GENERATOR, signature, pubkey, &s)
+    // The H(m) from the docs
+    let msg_hash = api.bls12_381_hash_to_g2(HashFunction::Sha256, msg, dst)?;
+    api.bls12_381_pairing_equality(&BLS12_381_G1_GENERATOR, signature, pubkey, &msg_hash)
         .map_err(Into::into)
 }
 
+/// Signature verification with public key in G2 (e.g. drand Quicknet)
+///
+/// See https://hackmd.io/@benjaminion/bls12-381#Verification in combination with
+/// https://hackmd.io/@benjaminion/bls12-381#Swapping-G1-and-G2.
 pub fn verify_g2(
     api: &dyn Api,
     signature: &[u8],
     pubkey: &[u8],
     msg: &[u8],
     dst: &[u8],
 ) -> StdResult<bool> {
-    let s = api.bls12_381_hash_to_g1(HashFunction::Sha256, msg, dst)?;
-    api.bls12_381_pairing_equality(signature, &BLS12_381_G2_GENERATOR, &s, pubkey)
+    // The H(m) from the docs
+    let msg_hash = api.bls12_381_hash_to_g1(HashFunction::Sha256, msg, dst)?;
+    api.bls12_381_pairing_equality(signature, &BLS12_381_G2_GENERATOR, &msg_hash, pubkey)
         .map_err(Into::into)
 }