whosigned.js

const {
  Client,
  Signature,
  cryptoUtils,
} = require('dsteem');


const client = new Client('https://api.steemit.com');

const args = process.argv.slice(2);

(async () => {
  // Pulling transaction data
  const trx = await client.database.getTransaction({ block_num: args[0], id: args[1] });

  // New signature object from transaction signature
  const sig = Signature.fromString(trx.signatures[0]);

  // Recreting transaction message
  const msg = {
    expiration: trx.expiration,
    extensions: trx.extensions,
    operations: trx.operations,
    ref_block_num: trx.ref_block_num,
    ref_block_prefix: trx.ref_block_prefix,
  };

  const digest = cryptoUtils.transactionDigest(msg);

  // Finding public key of the private that was used to sign
  const key = (new Signature(sig.data, sig.recovery)).recover(digest);

  const publicKey = key.toString();

  // Finding owner of that public key
  const [owner] = await client.database.call('get_key_references', [[publicKey]]);

  console.log(`Public Key: ${publicKey}`);
  console.log(`Owner: ${owner}`);
})();