Utilities to generate keypair from seed and build transaction with existing payload

[0x009922]

Request

There are two tasks:

• Provide utility to generate key pairs with some seed as input;
• Provide opportunity to build transaction using an existing payload as raw bytes.

Key pairs generation

The most efficient way to reach this goal and an ultimative solution for this is to completely port iroha_crypto crate into WASM. It is a big task and requires a lot of refactoring in Rust's sources.

Building transaction

I guess the solution for this will be a special TransactionBuilder helper that will provide several ways to build a transaction. I don't know how it will be looks like because it depends on how the new @iroha/crypto package will looks like.

[0x009922]

This issue may be resolved with https://github.com/hyperledger/iroha-javascript/pull/69.

Note that to use crypto you have to initialize it firstly. More about it in the README of the @iroha/crypto package

Key pairs generation

import { KeyGenConfiguration, KeyPair } from '@iroha2/crypto';

const SEED_BYTES = [49, 50, 51, 52];

const config = new KeyGenConfiguration().use_seed(Uint8Array.from(SEED_BYTES));
const keyPair = KeyPair.generate_with_configuration(config);

// now `keyPair` is usable in client

Having a payload as bytes, send transaction with it

import { types, createClient } from '@iroha2/client';
import { KeyPair } from '@iroha2/crypto';

// Having a payload of bytes
const PAYLOAD_BYTES = new Uint8Array([1, 2, 3 /* ... */]);
// And a KeyPair
const keyPair: KeyPair = /* ... */;

// firstly, decode payload into JS representation
const payloadDecoded = types.decode('iroha_data_model::transaction::Payload', PAYLOAD_BYTES);

// init a client
const client = createClient({
    toriiURL: 'http://localhost:8080',
});

// and submit a transaction
await client.submitTransaction({
    payload: payloadDecoded,
    signing: keyPair,
});