The use of RSA algorithm __rsa

1. Generate key

public static map<string, Object> Initkey () throws exception{keypairgenerator
        = Keypairgenerator.getinstance ("RSA");
        Keypairgenerator.initialize (1024);

        KeyPair KeyPair = Keypairgenerator.generatekeypair ();
        Rsapublickey Rsapublickey = (rsapublickey) keypair.getpublic ();
        Rsaprivatekey Rsaprivatekey = (rsaprivatekey) keypair.getprivate ();

        map<string, object> map = new hashmap<> ();
        Map.put (Public_key, rsapublickey);
        Map.put (Private_key, rsaprivatekey);

        return map;

    }

2. Use public key for encryption

public static byte[] Encryptrsa (byte[] data, Rsapublickey key) throws exception{Cipher Cipher
        = cipher.getinstance ( "RSA");
        Cipher.init (Cipher.encrypt_mode, key);
        byte[] Resultbytes = cipher.dofinal (data);
        return resultbytes;
    }

3. Decrypting with the private key

public static byte[] Decryptrsa (byte[] src, Rsaprivatekey key) throws exception{Cipher Cipher
        = Cipher.getinstance (" RSA ");
        Cipher.init (Cipher.decrypt_mode, key);
        byte[] plainbytes = cipher.dofinal (src);
        return plainbytes;
    }

4. Test

public class Client {public

    static final String DATA = "HelloWorld"; 

    public static void Main (string[] args) throws Exception {

        map<string, object> Map = Rsautil.initkey ();
        Rsaprivatekey Rsaprivatekey = Rsautil.getprivatekey (map);
        Rsapublickey Rsapublickey = Rsautil.getpublickey (map);

        byte[] resultbytes = Rsautil.encryptrsa (Data.getbytes (), rsapublickey);

        System.out.println ("RSA Encrypt:" + helper.frombytetohex (resultbytes));

        byte[] plainbytes = Rsautil.decryptrsa (resultbytes, rsaprivatekey);

        System.out.println ("RES Plain:" + new String (plainbytes));


    }

5. Results

rsa Encrypt: 50005af95cc6d79f22c4baf9c289926ef2afb48c0c1760eecbe2bacc22e989349af66cea1f12be343629f8889a6d06679924df445e4c59012753529c7 dffb563c783a2e45a20a8ca8ec0ee0fa74625cfce0a4f77cf4fea96c0d1c944ce2f4433aecc941fdd213f1186e8e71668e842acbc4c630a7befdbf20a 901af2da1718e4 RSA Plain:helloworld