php - rsa 加密算法中，如果客户端的公钥泄漏了，是否有安全危险

Question

RSA中公钥被被第三方知道后，第三方用公钥加密发送数据； 例如： A要给B写信： 1.B给A发送公钥 2.A拿到公钥加密信内容，发送内容给B 3.B拿到A的信后用私钥解密。 那么问题来了： 问题一：在B给A公钥时，被第三方C知道了，那么C是不是也可以给B写信了

Answer 1

The public key itself is public and can be known by anyone. The ciphertext encrypted by the public key can only be decrypted by the private key. Even the encrypted party cannot use the public key to decrypt the ciphertext, so no one who gets the public key can decrypt it.
If you want to talk about the issue of authentication, that is, C can pretend to be B and write to A, this involves the issue of authentication.

Answer 2

Public key, as the name suggests, is something you are not afraid of showing to others

Answer 3

Confusing data encryption with authentication.
The public key obtained by C is only used for data encryption.
In order for C to be able to successfully send data to B, it must pass B’s identity authentication level.
B’s identity authentication for C has nothing to do with B’s public key.