fix: BEEFY compact signed commitment in versioned finality proofs

[mfornos]

The present version of BEEFY sends the versioned finality proof as a CompactSignedCommitment over the wire.
In PolkadotJS the definition of VersionedFinalityProof is expecting an uncompressed signed commitment, therefore the decoded data is wrong (although it does not generate any decoding error).

You can verify the new definition using the following script:

import assert from 'node:assert/strict';

import { ApiPromise, WsProvider } from '@polkadot/api';
import { keccak256AsU8a, secp256k1Recover } from '@polkadot/util-crypto';

async function start() {
  const wsProvider = new WsProvider(
    'wss://rococo-rpc.polkadot.io'
    //'wss://kusama-rpc.polkadot.io'
  );
  const api = await ApiPromise.create({
    provider: wsProvider,
  });
  const authorities = (await api.query.beefy.authorities()).toHuman() as Array<string>;

  console.log('Waiting for BEEFY justifications...');

  api.rpc.beefy.subscribeJustifications(j => {
    const {
      commitment,
      signaturesFrom,
      signaturesCompact
    } = j.asV1;
    const commitmentHash = keccak256AsU8a(commitment.toU8a());
    const bitField = signaturesFrom.toU8a().slice(1);

    console.log({ justification: j.asV1.toHuman() });

    const sigs = signaturesCompact.values();

    for (let n = 0; n < bitField.length; n++) {
      const byte = bitField[n];
      for (let p = 0; p < 8; p++) {
        const bit = (byte >> (8 - p - 1)) & 1;
        if (bit === 1) {
          const i = (n * 8) + p;
          const sig = sigs.next().value.toU8a();
          const recoveryId = sig[64] > 26 ? sig[64] - 27 : sig[64];
          const pubKey =  secp256k1Recover(commitmentHash, sig.slice(0, 64), recoveryId);
          const hexPubKey = '0x' + Buffer.from(pubKey).toString('hex');

          assert.strictEqual(hexPubKey, authorities[i]);

          console.log(`Bit[${i}]: ${hexPubKey}`);
        }
      }
    }
  });
}

start();

[polkadot-js-bot]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.