Java

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. Java

import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    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.
    CkPublicKey pubKey = new CkPublicKey();
    //  In all Chilkat methods expecting a path, you pass either absolute or relative paths.
    success = pubKey.LoadFromFile("rsaKeys/myTestRsaPublic.pem");
    if (success == false) {
        System.out.println(pubKey.lastErrorText());
        return;
        }

    CkRsa rsa = new CkRsa();

    //  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.put_Charset("utf-8");
    rsa.put_EncodingMode("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.
    CkPrivateKey privKey = new CkPrivateKey();
    String password = "secret";
    success = privKey.LoadAnyFormatFile("rsaKeys/myTestRsaPrivate.pem",password);
    if (success == false) {
        System.out.println(privKey.lastErrorText());
        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.put_Charset("utf-8");
    rsa.put_EncodingMode("base64");
    String originalText = rsa.decryptStringENC(encryptedB64,true);
    if (success == false) {
        System.out.println(rsa.lastErrorText());
        return;
        }

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