RSA Encryption -- Same Key Different Results

The RSA encryption algorithm produces different results for each call, even when encrypting the same data with the same key. Decryption however, will produce the correct results. This example demonstrates.

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;
    }

    //  RSA public key in XML format:
    String publicKey;
    publicKey = "<RSAKeyValue><Modulus>xxyv1RDPU0MvfFIIa98HppXdcuI7zSu8uIqyGAy/VoxPvxZFX0acajznvjVRHipHbpcO6ryo2LwXUPf89qOqLb3Qd1lfD2ZnH+TQ6MZXNxfFRxTpTUd+tTR4EBYpd2t6kzq8ZRJYLdlviaMQQqUEwR54k7Op5HJYVKUcHIkP1xE=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";

    String privateKey;
    privateKey = "<RSAKeyValue><Modulus>xxyv1RDPU0MvfFIIa98HppXdcuI7zSu8uIqyGAy/VoxPvxZFX0acajznvjVRHipHbpcO6ryo2LwXUPf89qOqLb3Qd1lfD2ZnH+TQ6MZXNxfFRxTpTUd+tTR4EBYpd2t6kzq8ZRJYLdlviaMQQqUEwR54k7Op5HJYVKUcHIkP1xE=</Modulus><Exponent>AQAB</Exponent><P>4cpW9fvG99Jsz8/AO7PDHTl+pPRAglksrR2kClLV2g9DEeFe/bvmCxLUgMCJ+0eGQ1zA6aA7McKr13zTQ7jKpQ==</P><Q>4cCS/kFlq/P1ExF37Fkh4pCodOEGutepLEG7Q/KljT3ZGlAY+2l8fGu4f+hrkUuGoFl7NOMaJflULoPIgQaq/Q==</Q><DP>lkjcSsvzqh3YKRXJiLNkyf3rypV8noYGU4+oEOsDxilkZfFRDafUPUiiQrRk4ui/d/SzvozU+ZDuWfaOk8PatQ==</DP><DQ>SYCD25i7W8Mwdibn3uIecEAdOQDTSh5RjIFSUYs9b8FFYJXXrHPp/jCsf6jS7RmkGa1Iui1/JAIL8KEjtS7QmQ==</DQ><InverseQ>EDAJa3TpNdPQ3GIdBpnTgFTQY5A60DcszsUW/iCYoXQdPVJ9BLBxVTe9jiLzGuNuzLkVBwQlCy0Bf84hACRV9A==</InverseQ><D>cMFdDYKkddlRNczaugOmOH8b1egpx2liSPs6GYZ2gFObAXJiPK8m+r6c2ckls7hrlUP0DZhi4cG6Tn7xANb0Ek17P7QquVhQYOmFy/YHzm+IJbcwwq7pJHhZBhtcjyXqfUZ+BADGE//GQbrSVwVltpOj5KcxG88NAprLn2MMxfE=</D></RSAKeyValue>";

    rsa.ImportPublicKey(publicKey);

    //  Encrypt a string and return the encrypted data base64-encoded:
    rsa.put_EncodingMode("base64");

    String plainText;
    plainText = "RSA gives different results with each call, weird but OK";

    boolean usePrivateKey;
    usePrivateKey = false;
    String encryptedStr1;
    encryptedStr1 = rsa.encryptStringENC(plainText,usePrivateKey);
    System.out.println(encryptedStr1);

    //  Do it again. The results are different...
    String encryptedStr2;
    encryptedStr2 = rsa.encryptStringENC(plainText,usePrivateKey);
    System.out.println(encryptedStr2);

    //  Now decrypt both strings, and the results are correct
    //  in both cases:
    CkRsa rsa2 = new CkRsa();
    rsa2.ImportPrivateKey(privateKey);
    rsa2.put_EncodingMode("base64");
    usePrivateKey = true;

    String decryptedStr1;
    decryptedStr1 = rsa2.decryptStringENC(encryptedStr1,usePrivateKey);
    System.out.println(decryptedStr1);

    String decryptedStr2;
    decryptedStr2 = rsa2.decryptStringENC(encryptedStr2,usePrivateKey);
    System.out.println(decryptedStr2);


  }
}