Java example source code file (DESedeKeyFactory.java)

This example Java source code file (DESedeKeyFactory.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

cannot, class, crypto, desedekeyfactory, desedekeyspec, inappropriate, invalidkeyexception, invalidkeyspecexception, raw, secretkey, secretkeyfactoryspi, secretkeyspec, security

The DESedeKeyFactory.java Java example source code

/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.crypto.provider;

import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactorySpi;
import javax.crypto.spec.DESedeKeySpec;
import java.security.InvalidKeyException;
import java.security.spec.KeySpec;
import java.security.spec.InvalidKeySpecException;
import javax.crypto.spec.SecretKeySpec;

/**
 * This class implements the DES-EDE key factory of the Sun provider.
 *
 * @author Jan Luehe
 *
 */

public final class DESedeKeyFactory extends SecretKeyFactorySpi {

    /**
     * Empty constructor
     */
    public DESedeKeyFactory() {
    }

    /**
     * Generates a <code>SecretKey object from the provided key
     * specification (key material).
     *
     * @param keySpec the specification (key material) of the secret key
     *
     * @return the secret key
     *
     * @exception InvalidKeySpecException if the given key specification
     * is inappropriate for this key factory to produce a public key.
     */
    protected SecretKey engineGenerateSecret(KeySpec keySpec)
        throws InvalidKeySpecException {

        try {
            if (keySpec instanceof DESedeKeySpec) {
                return new DESedeKey(((DESedeKeySpec)keySpec).getKey());
            }
            if (keySpec instanceof SecretKeySpec) {
                return new DESedeKey(((SecretKeySpec)keySpec).getEncoded());

            }
            throw new InvalidKeySpecException
                ("Inappropriate key specification");
        } catch (InvalidKeyException e) {
            throw new InvalidKeySpecException(e.getMessage());
        }
    }

    /**
     * Returns a specification (key material) of the given key
     * in the requested format.
     *
     * @param key the key
     *
     * @param keySpec the requested format in which the key material shall be
     * returned
     *
     * @return the underlying key specification (key material) in the
     * requested format
     *
     * @exception InvalidKeySpecException if the requested key specification is
     * inappropriate for the given key, or the given key cannot be processed
     * (e.g., the given key has an unrecognized algorithm or format).
     */
    protected KeySpec engineGetKeySpec(SecretKey key, Class<?> keySpec)
        throws InvalidKeySpecException {

        try {
            if ((key instanceof SecretKey)
                && (key.getAlgorithm().equalsIgnoreCase("DESede"))
                && (key.getFormat().equalsIgnoreCase("RAW"))) {

                // Check if requested key spec is amongst the valid ones
                if (DESedeKeySpec.class.isAssignableFrom(keySpec)) {
                    return new DESedeKeySpec(key.getEncoded());

                } else {
                    throw new InvalidKeySpecException
                        ("Inappropriate key specification");
                }

            } else {
                throw new InvalidKeySpecException
                    ("Inappropriate key format/algorithm");
            }
        } catch (InvalidKeyException e) {
            throw new InvalidKeySpecException("Secret key has wrong size");
        }
    }

    /**
     * Translates a <code>SecretKey object, whose provider may be
     * unknown or potentially untrusted, into a corresponding
     * <code>SecretKey object of this key factory.
     *
     * @param key the key whose provider is unknown or untrusted
     *
     * @return the translated key
     *
     * @exception InvalidKeyException if the given key cannot be processed by
     * this key factory.
     */
    protected SecretKey engineTranslateKey(SecretKey key)
        throws InvalidKeyException {

        try {

            if ((key != null)
                && (key.getAlgorithm().equalsIgnoreCase("DESede"))
                && (key.getFormat().equalsIgnoreCase("RAW"))) {
                // Check if key originates from this factory
                if (key instanceof com.sun.crypto.provider.DESedeKey) {
                    return key;
                }
                // Convert key to spec
                DESedeKeySpec desEdeKeySpec
                    = (DESedeKeySpec)engineGetKeySpec(key,
                                                      DESedeKeySpec.class);
                // Create key from spec, and return it
                return engineGenerateSecret(desEdeKeySpec);

            } else {
                throw new InvalidKeyException
                    ("Inappropriate key format/algorithm");
            }

        } catch (InvalidKeySpecException e) {
            throw new InvalidKeyException("Cannot translate key");
        }
    }
}