RSA Encrypt and Decrypt Strings

Java sample code to RSA public-key encrypt and decrypt strings using public and private keys.

Download Chilkat Java Library

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[])
  {
    CkRsa rsa = new CkRsa();

    boolean success;
    success = rsa.UnlockComponent("Anything for 30-day trial");
    if (success != true) {
        System.out.println("RSA component unlock failed");
        return;
    }

    //  This example also generates the public and private
    //  keys to be used in the RSA encryption.
    //  Normally, you would generate a key pair once,
    //  and distribute the public key to your partner.
    //  Anything encrypted with the public key can be
    //  decrypted with the private key.  The reverse is
    //  also true: anything encrypted using the private
    //  key can be decrypted using the public key.

    //  Generate a 1024-bit key.  Chilkat RSA supports
    //  key sizes ranging from 512 bits to 16384 bits.
    success = rsa.GenerateKey(1024);
    if (success != true) {
        System.out.println(rsa.lastErrorText());
        return;
    }

    //  Keys are exported in XML format:
    String publicKey;
    publicKey = rsa.exportPublicKey();
    String privateKey;
    privateKey = rsa.exportPrivateKey();

    String plainText;
    plainText = "Encrypting and decrypting should be easy!";

    //  Start with a new RSA object to demonstrate that all we
    //  need are the keys previously exported:
    CkRsa rsaEncryptor = new CkRsa();

    //  Encrypted output is always binary.  In this case, we want
    //  to encode the encrypted bytes in a printable string.
    //  Our choices are "hex", "base64", "url", "quoted-printable".
    rsaEncryptor.put_EncodingMode("hex");

    //  We'll encrypt with the public key and decrypt with the private
    //  key.  It's also possible to do the reverse.
    rsaEncryptor.ImportPublicKey(publicKey);

    boolean usePrivateKey;
    usePrivateKey = false;
    String encryptedStr;
    encryptedStr = rsaEncryptor.encryptStringENC(plainText,usePrivateKey);
    System.out.println(encryptedStr);

    //  Now decrypt:
    CkRsa rsaDecryptor = new CkRsa();

    rsaDecryptor.put_EncodingMode("hex");
    rsaDecryptor.ImportPrivateKey(privateKey);

    usePrivateKey = true;
    String decryptedStr;
    decryptedStr = rsaDecryptor.decryptStringENC(encryptedStr,usePrivateKey);

    System.out.println(decryptedStr);
  }
}