必须有对称密钥才能解密，而且密钥必须单独管理。

You need a symmetric key to do the encryption, and the key must be managed independently.

youdao

同样，也可以将SignedObject用于数据验证，并且对称密钥也必须单独管理。

Likewise, you can use SignedObject for data verification, and again the symmetric key must be managed independently.

youdao

我们并不需要像Robin Hood那样劫富济贫的绿林方式，但在金融学值我们将通过风险管理的一种对称方式来实现。

We're not going to do that in a Robin Hood way; but in finance we're going to do that in a systematic way through risk management.

youdao