使用Egg.js始终无法校验成功

```
verifyWebhook() {
const { ctx } = this;
if (!ctx.request.headers['user-agent'].includes('Coding.net Hook')) {
return false;
}
const theirSignature = ctx.request.headers['x-coding-signature'];
const payload = JSON.stringify(ctx.request.body);
const secret = '123';
const ourSignature = `sha1=${crypto.createHmac('sha1', secret).update(payload).digest('hex')}`;
return crypto.timingSafeEqual(Buffer.from(theirSignature), Buffer.from(ourSignature));
// 始终返回false，怎么回事？？
}
}
```