1. Initialize keys to construct key pairs, generate public keys and private keys, and save them in the key map.

Key pair generator->; key pair-& gt； RSAPublicKey、RSAPrivateKey

2. Party A encrypts the encrypted data with the private key, and then signs the encrypted data with the private key and sends it to Party B.

RSA coder . encryptbyprivatekey(data，privateKey)；

RSACoder.sign(encodedData，private key)；

3. Party B verifies the signed encrypted data through the public key, and decrypts the encrypted data through the public key if the verification is correct.

RSACoder.verify(encodedData，publicKey，sign)；

RSA coder . decryptbypublickey(encoded data，public key)；

4. Party B sends it to Party A through public key encryption.

RSA coder . encryptbypublickey(decode ddata，public key)；

5. Party A decrypts the data through the private key.

RSA coder . decryptprivatekey(encoded data，private key)；