security - 使用单独的 key 对进行签名和加密的目的是什么？

Question

为什么我需要使用单独的公钥对进行签名和加密例如，不使用与 RSA 相同的 key 对？使用相同的 key 是否存在安全问题？

Answer 1

使用单独的 key 对进行签名和加密的原因是为了分散风险:如果有人恢复了私有(private)加密 key ，他/她可以解密使用公共(public)加密 key 加密的文档，但不能使用它来解密签署文件，反之亦然。

另一个原因可能是a legal reason :

In several countries, a digital signature has a status somewhat like that of a traditional pen and paper signature, like in the EU digital signature legislation. Generally, these provisions mean that anything digitally signed legally binds the signer of the document to the terms therein. For that reason, it is often thought best to use separate key pairs for encrypting and signing. Using the encryption key pair, a person can engage in an encrypted conversation (e.g., regarding a real estate transaction), but the encryption does not legally sign every message he sends. Only when both parties come to an agreement do they sign a contract with their signing keys, and only then are they legally bound by the terms of a specific document. After signing, the document can be sent over the encrypted link. If a signing key is lost or compromised, it can be revoked to mitigate any future transactions. If an encryption key is lost, a backup or key escrow should be utilized to continue viewing encrypted content. Signing keys should never be backed up or escrowed.