RSA Signature/Verify with .key and .cer

Demonstrates how to use a .key file (private key) and digital certificate (.cer, public key) to create and verify an RSA signature.

 Chilkat Java Library Downloads for Windows, Linux, and MAC OS X

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[])
  {
    CkPrivateKey privKey = new CkPrivateKey();

    boolean success;

    //  Load the private key from an RSA .key file:
    success = privKey.LoadPemFile("privateKey.key");
    if (success != true) {
        System.out.println(privKey.lastErrorText());
        return;
    }

    String privKeyXml;
    //  Get the private key in XML format:
    privKeyXml = privKey.getXml();

    CkRsa rsa = new CkRsa();

    //  Any string argument automatically begins the 30-day trial.

    success = rsa.UnlockComponent("30-day trial");
    if (success != true) {
        System.out.println(rsa.lastErrorText());
        return;
    }

    //  Import the private key into the RSA component:
    success = rsa.ImportPrivateKey(privKeyXml);
    if (success != true) {
        System.out.println(rsa.lastErrorText());
        return;
    }

    //  Create the signature as a hex string:
    rsa.put_EncodingMode("hex");

    //  If some other non-Chilkat application or web service is going to be verifying
    //  the signature, it is important to match the byte-ordering.
    //  The LittleEndian property may be set to true
    //  for little-endian byte ordering,
    //  or false  for big-endian byte ordering.
    //  Microsoft apps typically use little-endian, while
    //  OpenSSL and other services (such as Amazon CloudFront)
    //  use big-endian.
    rsa.put_LittleEndian(false);

    String strData;
    strData = "This is the string to be signed.";

    //  Sign the string using the sha-1 hash algorithm.
    //  Other valid choices are "md2", "sha256", "sha384",
    //  "sha512", and "md5".
    String hexSig;
    hexSig = rsa.signStringENC(strData,"sha-1");

    System.out.println(hexSig);

    //  Load a digital certificate from a .cer file:
    CkCert cert = new CkCert();

    success = cert.LoadFromFile("myCert.cer");
    if (success != true) {
        System.out.println(cert.lastErrorText());
        return;
    }

    CkPublicKey pubKey;

    pubKey = cert.ExportPublicKey();

    //  Now verify using a separate instance of the RSA object:
    CkRsa rsa2 = new CkRsa();

    //  Import the public key into the RSA object:
    success = rsa2.ImportPublicKey(pubKey.getXml());
    if (success != true) {
        System.out.println(rsa2.lastErrorText());
        return;
    }

    //  The signature is a hex string, so make sure the EncodingMode is correct:
    rsa2.put_EncodingMode("hex");

    //  Verify the signature:
    success = rsa2.VerifyStringENC(strData,"sha-1",hexSig);
    if (success != true) {
        System.out.println(rsa2.lastErrorText());
        return;
    }

    System.out.println("Success.");
  }
}