Java Requires Chilkat v11.0.0+

RSA Encrypt String to Encoded Result and Reverse

See more RSA Examples

Demonstrates how to RSA encrypt a string to a base64 encoded result, and the reverse. Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.PrivateKey;
import com.chilkatsoft.chilkat2.PublicKey;
import com.chilkatsoft.chilkat2.Rsa;

public class ChilkatExample {

    public static void main(String[] args) {
        boolean success = false;

        // The RSA public key is used for encryption, and the private key for decryption.

        // The public key's role is to make encryption accessible to anyone while ensuring that
        // only the private key holder can decrypt the messages.
        // The public key is designed to be widely distributed so anyone can use it to encrypt messages
        // intended for the owner of the private key.

        // Load our 2048-bit RSA public key.
        PublicKey pubKey = new PublicKey();
        // In all Chilkat methods expecting a path, you pass either absolute or relative paths.
        try {
            pubKey.loadFromFile("rsaKeys/myTestRsaPublic.pem");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        Rsa rsa = new Rsa();

        // Tell RSA to use the public key.
        rsa.usePublicKey(pubKey);

        // RSA encryption is for small amounts of data, on the order of 200 bytes or less.
        // The maximum number of bytes that can be RSA encrypted depends
        // on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
        // For specific limits, see: RSA Encryption Maximum Number of Bytes

        // Encrypt the utf-8 byte representation of the string.
        rsa.setCharset("utf-8");
        rsa.setEncodingMode("base64");

        // Be Careful when Using non-us-ascii String Literals in Source Code
        String encryptedB64 = rsa.encryptStringENC("Élève français dîne à côté d’un café où l’on sert déjà du gâteau au chocolat et des éclairs délicieux", false);

        // ------------------------------------------------------------------------------------------------------------------------
        // Let's decrypt, which requires the matching private key...

        // Load the matching 2048-bit RSA private key.
        PrivateKey privKey = new PrivateKey();
        String password = "secret";
        try {
            privKey.loadAnyFormatFile("rsaKeys/myTestRsaPrivate.pem", password);
            success = true;
        } catch (ChilkatException e) {
            success = false;
        }
        if (!success) {
            System.out.println(privKey.getLastErrorText());
            return;
        }

        // Tell the RSA object to use the private key.
        rsa.usePrivateKey(privKey);

        // Indicate that after decrypting the resultant decrypted bytes contains the utf-8 byte representation of the text.
        rsa.setCharset("utf-8");
        rsa.setEncodingMode("base64");
        String originalText = rsa.decryptStringENC(encryptedB64, true);
        if (!success) {
            System.out.println(rsa.getLastErrorText());
            return;
        }

        System.out.println("Original text = " + originalText);
        System.out.println("Success.");
    }
}