generate-signed-params.js

import clone from 'lodash.clone';
import crypto from 'crypto';
import defaults from 'lodash.defaults';
import keys from 'lodash.keys';

const debug = !!process.env.DEBUG;

export default function signedParams(method, path, host, keys, params = {}, utc = true) {
  params = defaults(clone(params), {
    access_key: keys.accessKey,
    timestamp: utc.toString() !== 'false' ? new Date().toISOString() : new Date().toLocaleString()
  });
  params.signature = generateHmacSignature(method, path, host, keys, params);
  return params;
}

function generateHmacSignature(method, path, host, keys, params) {
  const paramsCopy = clone(params);
  const signatureData = `${method.toUpperCase()};${host.toLowerCase()};${path};${buildSortedQuery(
    paramsCopy
  )}`;
  debug && console.log(`Signature data: ${signatureData}`);
  const hmac = crypto.createHmac('sha256', keys.secretKey.toUpperCase());
  hmac.update(signatureData);
  return hmac.digest('base64');
}

function buildSortedQuery(params) {
  // Sorted keys
  const _keys = keys(params).sort();
  let query = '';
  for (let i = 0, l = _keys.length; i < l; i++) {
    const value =
      typeof params[_keys[i]] === 'object'
        ? JSON.stringify(params[_keys[i]])
        : params[_keys[i]];
    query += `${encodeURIComponent(_keys[i])}=${encodeURIComponent(value)}&`;
  }
  query = query
    .replace(/\*/g, '%2A')
    .replace(/[!'()]/g, escape)
    .replace(/%7E/g, '~')
    .replace(/\+/g, '%20');
  // Strip the last separator and return
  return query.substring(0, query.length - 1);
}