Create an Ethereum Transaction

import { ApiClient } from "./api-client";
import * as AWS from "aws-sdk";

// Create instance of KMS for key signing
const kms = new AWS.KMS({ apiVersion: "2014-11-01", region: "eu-west-1" });

// Get the public Key (This will need to be your own custom code to pull the PublicKey from the AWS KMS publicKey which is a DER-encoded X.509 public key, also known as SubjectPublicKeyInfo (SPKI), 
// Sample code: https://github.com/Trustology/trustvault-nodejs-sdk/blob/master/src/ts/sign-examples/aws-kms.ts
// https://docs.aws.amazon.com/kms/latest/APIReference/API_GetPublicKey.html
const newPublicKey = getUncompressedPublicKeyInHex(await this.kms.getPublicKey({KeyId: "my-key"}).promise())

// For demonstration purposes only. Do not hard code your API key, store it somewhere safe.
const userApiKey = "test-api-key";
// Production
const prodUrl = "https://tapi-production.trustology-prod.com/graphql";
// API reflects the postman query written in JavaScript
const apiClient = new ApiClient(userApiKey, prodUrl);

/**
 * Sends an ethereum transaction with the given parameters
 * 1. Creates the ethereum transaction using the given parameters
 * 2. Validates the returned ethereum transaction is what is expected
 * 3. Signs and submits the key signature pairs
 * 2. Polls the request status to see if it has been successfully submitted to the network
 *
 * @param {string} from - the address where the ethereum transaction will be sent from (use the User Wallets Query to get your list of ethereum wallet addresses)
 * @param {string} to - the address where the ethereum transaction that will be sent to
 * @param {string} value - the amount to send in wei (integer string)
 * @param {string} assetSymbol - the symbol of the asset to be sent (ETH|RX|HOT|DAI2|BAT|DAI|EMR|VXV|MKR|OMG|PPT|REP|USDT|LINK|CBE)
 * @param {string} speed - "FAST" | "MEDIUM" | "SLOW"
 * @returns {string} requestId - the unique identifier of the created ethereum transaction request needed for transaction tracking
 */
async function sendEthereum(from, to, value, assetSymbol, speed) {
  // call createEthereumTransaction mutation with the parameters to get a well formed ethereum transaction
  const result = await apiClient.createEthereumTransaction(from, to, value, assetSymbol, speed);
  if (!result.signData || !result.requestId) {
    console.error(`Failed to create ethereum transaction ${JSON.stringify(result)}`);
    throw new Error("Failed to create ethereum transaction");
  }

  // IMPORTANT: PRODUCTION users are highly recommended to verify the ethereum transaction is what is expected (toAddress, amount, assetSymbol and digests are correct)
  verifyEthereumTransaction(result.signData, from, to, value, assetSymbol);

  // IMPORTANT: PRODUCTION users are highly recommended to NOT use the unverifiedDigestData but instead recreate the digests
  // If your signing solution requires the pre-image data then use the `result.signData.unverifiedDigestData.signData`.
  const signDigest = result.signData.unverifiedDigestData.shaSignData;
  // using you private key pair secured in KMS, sign the digest.
  // custom function. Use the sample code "sign" function and pull out the r,s values: https://github.com/Trustology/trustvault-nodejs-sdk/blob/master/src/ts/sign-examples/aws-kms.ts
  const { r, s } = signAndReturnRandSSignature(kms, signDigest);

  // create the signRequests payload
  const signRequests = [
    {
      publicKeySignaturePairs: [
        {
          publicKey: newPublicKey, // should be in hex string format
          signature: r.toString("hex", 64) + s.toString("hex", 64), // convert the r, s bytes signature to hex format
        },
      ],
    },
  ];

  // submit the addSignature payload and receive back the requestId of your ethereum transaction request
  const requestId = await apiClient.addSignature({
    requestId: result.requestId,
    signRequests,
  });

  // Check that your transaction was successfully submitted to the network
  const expectedStatus = "SUBMITTED";
  const status = await pollRequestStatus(requestId, expectedStatus);
  console.info(`request (${requestId}) - status: ${status}`);

  return requestId;
}