/*
 * @(#)KeyRep.java	1.7 04/04/20
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.security;

import java.io.*;

import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.security.spec.InvalidKeySpecException;

import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.SecretKeySpec;

/**
 * Standardized representation for serialized Key objects.
 *
 * <p>
 *
 * Note that a serialized Key may contain sensitive information
 * which should not be exposed in untrusted environments.  See the
 * <a href="../../../guide/serialization/spec/security.html">
 * Security Appendix</a>
 * of the Serialization Specification for more information.
 *
 * @see Key
 * @see KeyFactory
 * @see javax.crypto.spec.SecretKeySpec
 * @see java.security.spec.X509EncodedKeySpec
 * @see java.security.spec.PKCS8EncodedKeySpec
 *
 * @version 1.7, 04/04/20
 * @since 1.5
 */

public class KeyRep implements Serializable {
 
    private static final long serialVersionUID = -4757683898830641853L;

    /**
     * Key type.
     *
     * @since 1.5
     */
    public static enum Type {
    
	/** Type for secret keys. */
	SECRET, 
	
	/** Type for public keys. */
	PUBLIC, 
	
	/** Type for private keys. */
	PRIVATE,
    
    }

    private static final String PKCS8 = "PKCS#8";
    private static final String X509 = "X.509";
    private static final String RAW = "RAW";

    /**
     * Either one of Type.SECRET, Type.PUBLIC, or Type.PRIVATE
     *
     * @serial
     */
    private Type type;
 
    /**
     * The Key algorithm
     *
     * @serial
     */
    private String algorithm;
 
    /**
     * The Key encoding format
     *
     * @serial
     */
    private String format;
 
    /**
     * The encoded Key bytes
     *
     * @serial
     */
    private byte[] encoded;
 
    /**
     * Construct the alternate Key class.
     *
     * <p>
     *
     * @param type either one of Type.SECRET, Type.PUBLIC, or Type.PRIVATE
     * @param algorithm the algorithm returned from
     *		<code>Key.getAlgorithm()</code>
     * @param format the encoding format returned from
     *		<code>Key.getFormat()</code>
     * @param encoded the encoded bytes returned from
     *		<code>Key.getEncoded()</code>
     *
     * @exception NullPointerException
     *		if type is <code>null</code>,
     *		if algorithm is <code>null</code>,
     *		if format is <code>null</code>,
     *		or if encoded is <code>null</code>
     */
    public KeyRep(Type type, String algorithm,
		String format, byte[] encoded) {

	if (type == null || algorithm == null ||
	    format == null || encoded == null) {
	    throw new NullPointerException("invalid null input(s)");
	}

	this.type = type;
	this.algorithm = algorithm;
	this.format = format.toUpperCase();
	this.encoded = (byte[])encoded.clone();
    }
 
    /**
     * Resolve the Key object.
     *
     * <p> This method supports three Type/format combinations:
     * <ul>
     * <li> Type.SECRET/"RAW" - returns a SecretKeySpec object
     * constructed using encoded key bytes and algorithm
     * <li> Type.PUBLIC/"X.509" - gets a KeyFactory instance for
     * the key algorithm, constructs an X509EncodedKeySpec with the
     * encoded key bytes, and generates a public key from the spec
     * <li> Type.PRIVATE/"PKCS#8" - gets a KeyFactory instance for
     * the key algorithm, constructs a PKCS8EncodedKeySpec with the
     * encoded key bytes, and generates a private key from the spec
     * </ul>
     *
     * <p>
     *
     * @return the resolved Key object
     *
     * @exception NotSerializableException if the Type/format
     *	combination is unrecognized, if the algorithm, key format, or
     *	encoded key bytes are unrecognized/invalid, of if the
     *	resolution of the key fails for any reason
     */
    protected Object readResolve() throws ObjectStreamException {
	try {
	    if (type == Type.SECRET && RAW.equals(format)) {
		return new SecretKeySpec(encoded, algorithm);
	    } else if (type == Type.PUBLIC && X509.equals(format)) {
		KeyFactory f = KeyFactory.getInstance(algorithm);
		return f.generatePublic(new X509EncodedKeySpec(encoded));
	    } else if (type == Type.PRIVATE && PKCS8.equals(format)) {
		KeyFactory f = KeyFactory.getInstance(algorithm);
		return f.generatePrivate(new PKCS8EncodedKeySpec(encoded));
	    } else {
		throw new NotSerializableException
			("unrecognized type/format combination: " +
			type + "/" + format);
	    }
	} catch (NotSerializableException nse) {
	    throw nse;
	} catch (Exception e) {
	    NotSerializableException nse = new NotSerializableException
					("java.security.Key: " +
					"[" + type + "] " +
					"[" + algorithm + "] " +
					"[" + format + "]");
	    nse.initCause(e);
	    throw nse;
	}
    }
}