testSig.java Source code

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Here is the source code for testSig.java

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/* From http://java.sun.com/docs/books/tutorial/index.html */

/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
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 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
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 */

import java.io.FileInputStream;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.Signature;

public class testSig {

    public static void main(String[] args) {

        /* Test generating and verifying a DSA signature */

        try {

            /* generate a key pair */

            KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DSA");
            keyGen.initialize(1024, new SecureRandom());
            KeyPair pair = keyGen.generateKeyPair();

            /*
             * create a Signature object to use for signing and verifying
             */

            Signature dsa = Signature.getInstance("SHA/DSA");

            /* initialize the Signature object for signing */

            PrivateKey priv = pair.getPrivate();

            dsa.initSign(priv);

            /* Update and sign the data */

            FileInputStream fis = new FileInputStream(args[0]);
            byte b;
            while (fis.available() != 0) {
                b = (byte) fis.read();
                dsa.update(b);
            }
            ;

            fis.close();

            /*
             * Now that all the data to be signed has been read in, sign it
             */
            byte[] sig = dsa.sign();

            /* Verify the signature */

            /* Initialize the Signature object for verification */
            PublicKey pub = pair.getPublic();
            dsa.initVerify(pub);

            /* Update and verify the data */

            fis = new FileInputStream(args[0]);
            while (fis.available() != 0) {
                b = (byte) fis.read();
                dsa.update(b);
            }
            ;

            fis.close();

            boolean verifies = dsa.verify(sig);

            System.out.println("signature verifies: " + verifies);

        } catch (Exception e) {
            System.err.println("Caught exception " + e.toString());
        }

    }

}