Request wechat pay sandbox api sign key.

request-wepay-sandbox-key.ts

import * as $crypto from 'crypto';

const WEPAY_MCH_ID = 12345678;
const WEPAY_API_KEY = '';

const NONCE_STR = $crypto.randomBytes(16).toString('hex');

const REQ_SIGN = $crypto.createHash('md5')
    .update(`mch_id=${WEPAY_MCH_ID}&nonce_str=${NONCE_STR}&sign_type=MD5&key=${WEPAY_API_KEY}`)
    .digest('hex')
    .toUpperCase();

console.log(`<xml>
    <mch_id>${WEPAY_MCH_ID}</mch_id>
    <nonce_str>${NONCE_STR}</nonce_str>
    <sign_type>MD5</sign_type>
    <sign>${REQ_SIGN}</sign>
</xml>`);

// curl -X POST curl -X POST 'https://api.mch.weixin.qq.com/sandboxnew/pay/getsignkey' -H 'Content-Type: application/xml' -d '...'