How to encrypt rsa public key in ios and decrypt rsa private key in java?

1. Encrypted with public key and decrypted with private key.

2. If you send a message to someone, you will pull someone else's public key from the server, encrypt it and send it to him.

3. After receiving the message, the other party decrypts it with its own private key.

In this way, after the public key is encrypted, no one can see the information except the private key holder.

5. If it is encrypted with a private key, then the public key can be decrypted. How safe is it?

6. There is only one occasion for private key encryption, that is, digital signature, to show that this information comes from you.