(Java) RSA Sign with PKCS8 Encrypted Key

Demonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it).

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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[])
  {
    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkPrivateKey pkey = new CkPrivateKey();

    // Load the private key from an RSA PEM file:
    boolean success = pkey.LoadPkcs8EncryptedFile("raul_privateKey.key","a0123456789");

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

    CkRsa rsa = new CkRsa();

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

    // This example will sign a string, and receive the signature
    // in a hex-encoded string.  Therefore, set the encoding mode
    // to "hex":
    rsa.put_EncodingMode("hex");

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

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

    System.out.println(hexSig);

    // Now verify with the public key.
    // This example shows how to use the public key from 
    // a digital certificate (.cer file)
    CkCert cert = new CkCert();
    success = cert.LoadFromFile("raul_publicKey.cer");
    if (success != true) {
        System.out.println(cert.lastErrorText());
        return;
        }

    CkPublicKey pubKey;
    pubKey = cert.ExportPublicKey();

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

    CkRsa rsa2 = new CkRsa();
    success = rsa2.ImportPublicKey(pubKeyXml);
    if (success != true) {
        System.out.println(rsa2.lastErrorText());
        return;
        }

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

    System.out.println("Signature verified!");

    // Verify with incorrect data:
    success = rsa2.VerifyStringENC("something else","sha-1",hexSig);
    if (success != true) {
        System.out.println("Signature not verified! (which was expected in this case)");
        }
    else {
        System.out.println("Hmmm... that's not right...");
        }
  }
}