/*
 * @(#)KeyStore.java	1.53 06/07/28
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.security;

import java.io.*;
import java.security.cert.Certificate;
import java.security.cert.X509Certificate;
import java.security.cert.CertificateException;
import java.util.*;
import javax.crypto.SecretKey;

import javax.security.auth.callback.*;

/**
 * This class represents a storage facility for cryptographic
 * keys and certificates.
 *
 * <p> A <code>KeyStore</code> manages different types of entries.
 * Each type of entry implements the <code>KeyStore.Entry</code> interface.
 * Three basic <code>KeyStore.Entry</code> implementations are provided:
 *
 * <ul>
 * <li><b>KeyStore.PrivateKeyEntry</b>
 * <p> This type of entry holds a cryptographic <code>PrivateKey</code>,
 * which is optionally stored in a protected format to prevent
 * unauthorized access.  It is also accompanied by a certificate chain
 * for the corresponding public key.
 *
 * <p> Private keys and certificate chains are used by a given entity for
 * self-authentication. Applications for this authentication include software
 * distribution organizations which sign JAR files as part of releasing
 * and/or licensing software.
 *
 * <li><b>KeyStore.SecretKeyEntry</b>
 * <p> This type of entry holds a cryptographic <code>SecretKey</code>,
 * which is optionally stored in a protected format to prevent
 * unauthorized access.
 *
 * <li><b>KeyStore.TrustedCertificateEntry</b>
 * <p> This type of entry contains a single public key <code>Certificate</code>
 * belonging to another party. It is called a <i>trusted certificate</i>
 * because the keystore owner trusts that the public key in the certificate
 * indeed belongs to the identity identified by the <i>subject</i> (owner)
 * of the certificate.
 *
 * <p>This type of entry can be used to authenticate other parties.
 * </ul>
 *
 * <p> Each entry in a keystore is identified by an "alias" string. In the
 * case of private keys and their associated certificate chains, these strings
 * distinguish among the different ways in which the entity may authenticate
 * itself. For example, the entity may authenticate itself using different
 * certificate authorities, or using different public key algorithms.
 *
 * <p> Whether aliases are case sensitive is implementation dependent. In order
 * to avoid problems, it is recommended not to use aliases in a KeyStore that
 * only differ in case.
 *
 * <p> Whether keystores are persistent, and the mechanisms used by the
 * keystore if it is persistent, are not specified here. This allows
 * use of a variety of techniques for protecting sensitive (e.g., private or
 * secret) keys. Smart cards or other integrated cryptographic engines
 * (SafeKeyper) are one option, and simpler mechanisms such as files may also
 * be used (in a variety of formats).
 *
 * <p> Typical ways to request a KeyStore object include
 * relying on the default type and providing a specific keystore type.
 *
 * <ul>
 * <li>To rely on the default type:
 * <pre>
 *    KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
 * </pre>
 * The system will return a keystore implementation for the default type.
 * <p>
 *
 * <li>To provide a specific keystore type:
 * <pre>
 *      KeyStore ks = KeyStore.getInstance("JKS");
 * </pre>
 * The system will return the most preferred implementation of the
 * specified keystore type available in the environment. <p>
 * </ul>
 *
 * <p> Before a keystore can be accessed, it must be
 * {@link #load(java.io.InputStream, char[]) loaded}.
 * <pre>
 *    KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
 *
 *    // get user password and file input stream
 *    char[] password = getPassword();
 *
 *    java.io.FileInputStream fis = null;
 *    try {
 *        fis = new java.io.FileInputStream("keyStoreName");
 *        ks.load(fis, password);
 *    } finally {
 *        if (fis != null) {
 *            fis.close();
 *        }
 *    }
 * </pre>
 *
 * To create an empty keystore using the above <code>load</code> method,
 * pass <code>null</code> as the <code>InputStream</code> argument.
 *
 * <p> Once the keystore has been loaded, it is possible
 * to read existing entries from the keystore, or to write new entries
 * into the keystore:
 * <pre>
 *    // get my private key
 *    KeyStore.PrivateKeyEntry pkEntry = (KeyStore.PrivateKeyEntry)
 *        ks.getEntry("privateKeyAlias", password);
 *    PrivateKey myPrivateKey = pkEntry.getPrivateKey();
 *
 *    // save my secret key
 *    javax.crypto.SecretKey mySecretKey;
 *    KeyStore.SecretKeyEntry skEntry =
 *        new KeyStore.SecretKeyEntry(mySecretKey);
 *    ks.setEntry("secretKeyAlias", skEntry, 
 *        new KeyStore.PasswordProtection(password));
 *
 *    // store away the keystore
 *    java.io.FileOutputStream fos = null;
 *    try {
 *        fos = new java.io.FileOutputStream("newKeyStoreName");
 *        ks.store(fos, password);
 *    } finally {
 *        if (fos != null) {
 *            fos.close();
 *        }
 *    }
 * </pre>
 *
 * Note that although the same password may be used to
 * load the keystore, to protect the private key entry,
 * to protect the secret key entry, and to store the keystore
 * (as is shown in the sample code above),
 * different passwords or other protection parameters
 * may also be used.
 *
 * @author Jan Luehe
 *
 * @version 1.53, 07/28/06
 *
 * @see java.security.PrivateKey
 * @see javax.crypto.SecretKey
 * @see java.security.cert.Certificate
 *
 * @since 1.2
 */

public class KeyStore {

    /*
     * Constant to lookup in the Security properties file to determine
     * the default keystore type.
     * In the Security properties file, the default keystore type is given as:
     * <pre>
     * keystore.type=jks
     * </pre>
     */  
    private static final String KEYSTORE_TYPE = "keystore.type";

    // The keystore type
    private String type;

    // The provider
    private Provider provider;

    // The provider implementation
    private KeyStoreSpi keyStoreSpi;

    // Has this keystore been initialized (loaded)?
    private boolean initialized = false;

    /**
     * A marker interface for <code>KeyStore</code>
     * {@link #load(KeyStore.LoadStoreParameter) load}
     * and
     * {@link #store(KeyStore.LoadStoreParameter) store}
     * parameters.
     *
     * @since 1.5
     */
    public static interface LoadStoreParameter {
	/**
	 * Gets the parameter used to protect keystore data.
	 *
	 * @return the parameter used to protect keystore data, or null
	 */
	public ProtectionParameter getProtectionParameter();
    }

    /**
     * A marker interface for keystore protection parameters.
     *
     * <p> The information stored in a <code>ProtectionParameter</code>
     * object protects the contents of a keystore.
     * For example, protection parameters may be used to check
     * the integrity of keystore data, or to protect the
     * confidentiality of sensitive keystore data
     * (such as a <code>PrivateKey</code>).
     *
     * @since 1.5
     */
    public static interface ProtectionParameter { }

    /**
     * A password-based implementation of <code>ProtectionParameter</code>.
     *
     * @since 1.5
     */
    public static class PasswordProtection implements
		ProtectionParameter, javax.security.auth.Destroyable {

	private final char[] password;
	private volatile boolean destroyed = false;

	/**
	 * Creates a password parameter.
	 *
	 * <p> The specified <code>password</code> is cloned before it is stored
	 * in the new <code>PasswordProtection</code> object.
	 *
	 * @param password the password, which may be <code>null</code>
	 */
	public PasswordProtection(char[] password) {
	    this.password = (password == null) ?
				null : (char[])password.clone();
	}

	/**
	 * Gets the password.
	 *
	 * <p>Note that this method returns a reference to the password.
	 * If a clone of the array is created it is the caller's
	 * responsibility to zero out the password information
	 * after it is no longer needed.
	 *
	 * @see #destroy()
	 * @return the password, which may be <code>null</code>
	 * @exception IllegalStateException if the password has
	 *		been cleared (destroyed)
	 */
	public synchronized char[] getPassword() {
	    if (destroyed) {
		throw new IllegalStateException("password has been cleared");
	    }
	    return password;
	}

	/**
	 * Clears the password.
	 *
	 * @exception DestroyFailedException if this method was unable
	 *	to clear the password
	 */
	public synchronized void destroy()
		throws javax.security.auth.DestroyFailedException {
	    destroyed = true;
	    if (password != null) {
		Arrays.fill(password, ' ');
	    }
	}

	/**
	 * Determines if password has been cleared.
	 *
	 * @return true if the password has been cleared, false otherwise
	 */
	public synchronized boolean isDestroyed() {
	    return destroyed;
	}
    }

    /**
     * A ProtectionParameter encapsulating a CallbackHandler.
     *
     * @since 1.5
     */
    public static class CallbackHandlerProtection 
	    implements ProtectionParameter {
		
	private final CallbackHandler handler;
	
	/**
	 * Constructs a new CallbackHandlerProtection from a
	 * CallbackHandler.
	 *
	 * @param handler the CallbackHandler
	 * @exception NullPointerException if handler is null
	 */
	public CallbackHandlerProtection(CallbackHandler handler) {
	    if (handler == null) {
		throw new NullPointerException("handler must not be null");
	    }
	    this.handler = handler;
	}
	
	/**
	 * Returns the CallbackHandler.
	 *
	 * @return the CallbackHandler.
	 */
	public CallbackHandler getCallbackHandler() {
	    return handler;
	}
	
    }

    /**
     * A marker interface for <code>KeyStore</code> entry types.
     *
     * @since 1.5
     */
    public static interface Entry { }

    /**
     * A <code>KeyStore</code> entry that holds a <code>PrivateKey</code>
     * and corresponding certificate chain.
     *
     * @since 1.5
     */
    public static final class PrivateKeyEntry implements Entry {

	private final PrivateKey privKey;
	private final Certificate[] chain;

	/**
	 * Constructs a <code>PrivateKeyEntry</code> with a
	 * <code>PrivateKey</code> and corresponding certificate chain.
	 *
	 * <p> The specified <code>chain</code> is cloned before it is stored
	 * in the new <code>PrivateKeyEntry</code> object.
	 *
	 * @param privateKey the <code>PrivateKey</code>
	 * @param chain an array of <code>Certificate</code>s
	 *	representing the certificate chain.
	 *	The chain must be ordered and contain a
	 *	<code>Certificate</code> at index 0
	 *	corresponding to the private key.
	 *
	 * @exception NullPointerException if
	 *	<code>privateKey</code> or <code>chain</code>
	 *	is <code>null</code>
	 * @exception IllegalArgumentException if the specified chain has a
	 *	length of 0, if the specified chain does not contain
	 *	<code>Certificate</code>s of the same type,
	 *	or if the <code>PrivateKey</code> algorithm
	 *	does not match the algorithm of the <code>PublicKey</code>
	 *	in the end entity <code>Certificate</code> (at index 0)
	 */
	public PrivateKeyEntry(PrivateKey privateKey, Certificate[] chain) {
	    if (privateKey == null || chain == null) {
		throw new NullPointerException("invalid null input");
	    }
	    if (chain.length == 0) {
		throw new IllegalArgumentException
				("invalid zero-length input chain");
	    }

	    Certificate[] clonedChain = (Certificate[])chain.clone();
	    String certType = clonedChain[0].getType();
	    for (int i = 1; i < clonedChain.length; i++) {
		if (!certType.equals(clonedChain[i].getType())) {
		    throw new IllegalArgumentException
				("chain does not contain certificates " +
				"of the same type");
		}
	    }
	    if (!privateKey.getAlgorithm().equals
			(clonedChain[0].getPublicKey().getAlgorithm())) {
		throw new IllegalArgumentException
				("private key algorithm does not match " +
				"algorithm of public key in end entity " +
				"certificate (at index 0)");
	    }
	    this.privKey = privateKey;

	    if (clonedChain[0] instanceof X509Certificate &&
		!(clonedChain instanceof X509Certificate[])) {

		this.chain = new X509Certificate[clonedChain.length];
		System.arraycopy(clonedChain, 0,
				this.chain, 0, clonedChain.length);
	    } else {
		this.chain = clonedChain;
	    }
	}

	/**
	 * Gets the <code>PrivateKey</code> from this entry.
	 *
	 * @return the <code>PrivateKey</code> from this entry
	 */
	public PrivateKey getPrivateKey() {
	    return privKey;
	}

	/**
	 * Gets the <code>Certificate</code> chain from this entry.
	 *
	 * <p> The stored chain is cloned before being returned.
	 *
	 * @return an array of <code>Certificate</code>s corresponding
	 *	to the certificate chain for the public key.
	 *	If the certificates are of type X.509,
	 *	the runtime type of the returned array is
	 *	<code>X509Certificate[]</code>.
	 */
	public Certificate[] getCertificateChain() {
	    return (Certificate[])chain.clone();
	}

	/**
	 * Gets the end entity <code>Certificate</code>
	 * from the certificate chain in this entry.
	 *
	 * @return the end entity <code>Certificate</code> (at index 0)
	 *	from the certificate chain in this entry.
	 *	If the certificate is of type X.509,
	 *	the runtime type of the returned certificate is
	 *	<code>X509Certificate</code>.
	 */
	public Certificate getCertificate() {
	    return chain[0];
	}

	/**
	 * Returns a string representation of this PrivateKeyEntry.
	 * @return a string representation of this PrivateKeyEntry.
	 */	
	public String toString() {
	    StringBuilder sb = new StringBuilder();
	    sb.append("Private key entry and certificate chain with "
		+ chain.length + " elements:\r\n");
	    for (Certificate cert : chain) {
		sb.append(cert);
		sb.append("\r\n");
	    }
	    return sb.toString();
	}

    }

    /**
     * A <code>KeyStore</code> entry that holds a <code>SecretKey</code>.
     *
     * @since 1.5
     */
    public static final class SecretKeyEntry implements Entry {

	private final SecretKey sKey;

	/**
	 * Constructs a <code>SecretKeyEntry</code> with a
	 * <code>SecretKey</code>.
	 *
	 * @param secretKey the <code>SecretKey</code>
	 *
	 * @exception NullPointerException if <code>secretKey</code>
	 *	is <code>null</code>
	 */
	public SecretKeyEntry(SecretKey secretKey) {
	    if (secretKey == null) {
		throw new NullPointerException("invalid null input");
	    }
	    this.sKey = secretKey;
	}

	/**
	 * Gets the <code>SecretKey</code> from this entry.
	 *
	 * @return the <code>SecretKey</code> from this entry
	 */
	public SecretKey getSecretKey() {
	    return sKey;
	}
	
	/**
	 * Returns a string representation of this SecretKeyEntry.
	 * @return a string representation of this SecretKeyEntry.
	 */	
	public String toString() {
	    return "Secret key entry with algorithm " + sKey.getAlgorithm();
	}
    }

    /**
     * A <code>KeyStore</code> entry that holds a trusted
     * <code>Certificate</code>.
     *
     * @since 1.5
     */
    public static final class TrustedCertificateEntry implements Entry {

	private final Certificate cert;

	/**
	 * Constructs a <code>TrustedCertificateEntry</code> with a
	 * trusted <code>Certificate</code>.
	 *
	 * @param trustedCert the trusted <code>Certificate</code>
	 *
	 * @exception NullPointerException if
	 *	<code>trustedCert</code> is <code>null</code>
	 */
	public TrustedCertificateEntry(Certificate trustedCert) {
	    if (trustedCert == null) {
		throw new NullPointerException("invalid null input");
	    }
	    this.cert = trustedCert;
	}

	/**
	 * Gets the trusted <code>Certficate</code> from this entry.
	 *
	 * @return the trusted <code>Certificate</code> from this entry
	 */
	public Certificate getTrustedCertificate() {
	    return cert;
	}
	
	/**
	 * Returns a string representation of this TrustedCertificateEntry.
	 * @return a string representation of this TrustedCertificateEntry.
	 */	
	public String toString() {
	    return "Trusted certificate entry:\r\n" + cert.toString();
	}
    }

    /**
     * Creates a KeyStore object of the given type, and encapsulates the given
     * provider implementation (SPI object) in it.
     *
     * @param keyStoreSpi the provider implementation.
     * @param provider the provider.
     * @param type the keystore type.
     */
    protected KeyStore(KeyStoreSpi keyStoreSpi, Provider provider, String type)
    {
	this.keyStoreSpi = keyStoreSpi;
	this.provider = provider;
	this.type = type;
    }

    /**
     * Returns a keystore object of the specified type.
     * 
     * <p> This method traverses the list of registered security Providers,
     * starting with the most preferred Provider.
     * A new KeyStore object encapsulating the
     * KeyStoreSpi implementation from the first
     * Provider that supports the specified type is returned.
     *
     * <p> Note that the list of registered providers may be retrieved via
     * the {@link Security#getProviders() Security.getProviders()} method.
     *
     * @param type the type of keystore. 
     * See Appendix A in the <a href=
     * "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
     * Java Cryptography Architecture API Specification &amp; Reference </a> 
     * for information about standard keystore types.
     *
     * @return a keystore object of the specified type.
     *
     * @exception KeyStoreException if no Provider supports a
     *          KeyStoreSpi implementation for the
     *          specified type.
     *
     * @see Provider
     */
    public static KeyStore getInstance(String type) 
	throws KeyStoreException
    {
	try {
	    Object[] objs = Security.getImpl(type, "KeyStore", (String)null);
	    return new KeyStore((KeyStoreSpi)objs[0], (Provider)objs[1], type);
	} catch (NoSuchAlgorithmException nsae) {
	    throw new KeyStoreException(type + " not found", nsae);
	} catch (NoSuchProviderException nspe) {
	    throw new KeyStoreException(type + " not found", nspe);
	}
    }

    /**
     * Returns a keystore object of the specified type.
     * 
     * <p> A new KeyStore object encapsulating the
     * KeyStoreSpi implementation from the specified provider
     * is returned.  The specified provider must be registered
     * in the security provider list.
     *
     * <p> Note that the list of registered providers may be retrieved via
     * the {@link Security#getProviders() Security.getProviders()} method.
     *
     * @param type the type of keystore.
     * See Appendix A in the <a href=
     * "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
     * Java Cryptography Architecture API Specification &amp; Reference </a> 
     * for information about standard keystore types.
     *
     * @param provider the name of the provider.
     *
     * @return a keystore object of the specified type.
     *
     * @exception KeyStoreException if a KeyStoreSpi
     *          implementation for the specified type is not
     *          available from the specified provider.
     * 
     * @exception NoSuchProviderException if the specified provider is not
     *          registered in the security provider list.
     *
     * @exception IllegalArgumentException if the provider name is null
     *		or empty.
     *
     * @see Provider
     */
    public static KeyStore getInstance(String type, String provider)
	throws KeyStoreException, NoSuchProviderException
    {
	if (provider == null || provider.length() == 0)
	    throw new IllegalArgumentException("missing provider");
	try {
	    Object[] objs = Security.getImpl(type, "KeyStore", provider);
	    return new KeyStore((KeyStoreSpi)objs[0], (Provider)objs[1], type);
	} catch (NoSuchAlgorithmException nsae) {
	    throw new KeyStoreException(type + " not found", nsae);
	}
    }

    /**
     * Returns a keystore object of the specified type.
     * 
     * <p> A new KeyStore object encapsulating the
     * KeyStoreSpi implementation from the specified Provider
     * object is returned.  Note that the specified Provider object
     * does not have to be registered in the provider list.
     *
     * @param type the type of keystore.
     * See Appendix A in the <a href=
     * "../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
     * Java Cryptography Architecture API Specification &amp; Reference </a> 
     * for information about standard keystore types.
     *
     * @param provider the provider.
     *
     * @return a keystore object of the specified type.
     *
     * @exception KeyStoreException if KeyStoreSpi
     *          implementation for the specified type is not available
     *          from the specified Provider object.
     *
     * @exception IllegalArgumentException if the specified provider is null.
     *
     * @see Provider
     *
     * @since 1.4
     */
    public static KeyStore getInstance(String type, Provider provider)
	throws KeyStoreException
    {
	if (provider == null)
	    throw new IllegalArgumentException("missing provider");
	try {
	    Object[] objs = Security.getImpl(type, "KeyStore", provider);
	    return new KeyStore((KeyStoreSpi)objs[0], (Provider)objs[1], type);
	} catch (NoSuchAlgorithmException nsae) {
	    throw new KeyStoreException(type + " not found", nsae);
	}
    }

    /**
     * Returns the default keystore type as specified in the Java security
     * properties file, or the string
     * &quot;jks&quot; (acronym for &quot;Java keystore&quot;)
     * if no such property exists.
     * The Java security properties file is located in the file named
     * &lt;JAVA_HOME&gt;/lib/security/java.security.
     * &lt;JAVA_HOME&gt; refers to the value of the java.home system property,
     * and specifies the directory where the JRE is installed.
     *
     * <p>The default keystore type can be used by applications that do not
     * want to use a hard-coded keystore type when calling one of the
     * <code>getInstance</code> methods, and want to provide a default keystore
     * type in case a user does not specify its own.
     *
     * <p>The default keystore type can be changed by setting the value of the
     * "keystore.type" security property (in the Java security properties
     * file) to the desired keystore type.
     *
     * @return the default keystore type as specified in the 
     * Java security properties file, or the string &quot;jks&quot;
     * if no such property exists.
     */
    public final static String getDefaultType() {
	String kstype;
	kstype = (String)AccessController.doPrivileged(new PrivilegedAction() {
	    public Object run() {
		return Security.getProperty(KEYSTORE_TYPE);
	    }
	});
	if (kstype == null) {
	    kstype = "jks";
	}
	return kstype;
    }

    /** 
     * Returns the provider of this keystore.
     * 
     * @return the provider of this keystore.
     */
    public final Provider getProvider()
    {
	return this.provider;
    }

    /**
     * Returns the type of this keystore.
     *
     * @return the type of this keystore.
     */
    public final String getType()
    {
	return this.type;
    }

    /**
     * Returns the key associated with the given alias, using the given
     * password to recover it.  The key must have been associated with
     * the alias by a call to <code>setKeyEntry</code>,
     * or by a call to <code>setEntry</code> with a
     * <code>PrivateKeyEntry</code> or <code>SecretKeyEntry</code>.
     *
     * @param alias the alias name
     * @param password the password for recovering the key
     *
     * @return the requested key, or null if the given alias does not exist
     * or does not identify a key-related entry.
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded).
     * @exception NoSuchAlgorithmException if the algorithm for recovering the
     * key cannot be found
     * @exception UnrecoverableKeyException if the key cannot be recovered
     * (e.g., the given password is wrong).
     */
    public final Key getKey(String alias, char[] password)
	throws KeyStoreException, NoSuchAlgorithmException,
	    UnrecoverableKeyException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	return keyStoreSpi.engineGetKey(alias, password);
    }

    /**
     * Returns the certificate chain associated with the given alias.
     * The certificate chain must have been associated with the alias
     * by a call to <code>setKeyEntry</code>,
     * or by a call to <code>setEntry</code> with a
     * <code>PrivateKeyEntry</code>.
     *
     * @param alias the alias name
     *
     * @return the certificate chain (ordered with the user's certificate first
     * and the root certificate authority last), or null if the given alias
     * does not exist or does not contain a certificate chain
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded).
     */
    public final Certificate[] getCertificateChain(String alias)
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	return keyStoreSpi.engineGetCertificateChain(alias);
    }

    /**
     * Returns the certificate associated with the given alias.
     *
     * <p> If the given alias name identifies an entry
     * created by a call to <code>setCertificateEntry</code>,
     * or created by a call to <code>setEntry</code> with a
     * <code>TrustedCertificateEntry</code>,
     * then the trusted certificate contained in that entry is returned.
     *
     * <p> If the given alias name identifies an entry
     * created by a call to <code>setKeyEntry</code>,
     * or created by a call to <code>setEntry</code> with a
     * <code>PrivateKeyEntry</code>,
     * then the first element of the certificate chain in that entry
     * is returned.
     * 
     * @param alias the alias name
     *
     * @return the certificate, or null if the given alias does not exist or
     * does not contain a certificate.
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded).
     */
    public final Certificate getCertificate(String alias)
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	return keyStoreSpi.engineGetCertificate(alias);
    }

    /**
     * Returns the creation date of the entry identified by the given alias.
     *
     * @param alias the alias name
     *
     * @return the creation date of this entry, or null if the given alias does
     * not exist
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded).
     */
    public final Date getCreationDate(String alias)
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	return keyStoreSpi.engineGetCreationDate(alias);
    }

    /**
     * Assigns the given key to the given alias, protecting it with the given
     * password.
     *
     * <p>If the given key is of type <code>java.security.PrivateKey</code>,
     * it must be accompanied by a certificate chain certifying the
     * corresponding public key.
     *
     * <p>If the given alias already exists, the keystore information
     * associated with it is overridden by the given key (and possibly
     * certificate chain).
     *
     * @param alias the alias name
     * @param key the key to be associated with the alias
     * @param password the password to protect the key
     * @param chain the certificate chain for the corresponding public
     * key (only required if the given key is of type
     * <code>java.security.PrivateKey</code>).
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded), the given key cannot be protected, or this operation fails
     * for some other reason
     */
    public final void setKeyEntry(String alias, Key key, char[] password,
				  Certificate[] chain)
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	if ((key instanceof PrivateKey) && 
	    (chain == null || chain.length == 0)) {
	    throw new IllegalArgumentException("Private key must be "
					       + "accompanied by certificate "
					       + "chain");
	}
	keyStoreSpi.engineSetKeyEntry(alias, key, password, chain);
    }

    /**
     * Assigns the given key (that has already been protected) to the given
     * alias.
     * 
     * <p>If the protected key is of type
     * <code>java.security.PrivateKey</code>, it must be accompanied by a
     * certificate chain certifying the corresponding public key. If the
     * underlying keystore implementation is of type <code>jks</code>,
     * <code>key</code> must be encoded as an
     * <code>EncryptedPrivateKeyInfo</code> as defined in the PKCS #8 standard.
     *
     * <p>If the given alias already exists, the keystore information
     * associated with it is overridden by the given key (and possibly
     * certificate chain).
     *
     * @param alias the alias name
     * @param key the key (in protected format) to be associated with the alias
     * @param chain the certificate chain for the corresponding public
     *		key (only useful if the protected key is of type
     *		<code>java.security.PrivateKey</code>).
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded), or if this operation fails for some other reason.
     */
    public final void setKeyEntry(String alias, byte[] key,
				  Certificate[] chain)
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	keyStoreSpi.engineSetKeyEntry(alias, key, chain);
    }

    /**
     * Assigns the given trusted certificate to the given alias.
     *
     * <p> If the given alias identifies an existing entry
     * created by a call to <code>setCertificateEntry</code>,
     * or created by a call to <code>setEntry</code> with a
     * <code>TrustedCertificateEntry</code>,
     * the trusted certificate in the existing entry
     * is overridden by the given certificate.
     *
     * @param alias the alias name
     * @param cert the certificate
     *
     * @exception KeyStoreException if the keystore has not been initialized,
     * or the given alias already exists and does not identify an
     * entry containing a trusted certificate,
     * or this operation fails for some other reason.
     */
    public final void setCertificateEntry(String alias, Certificate cert)
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	keyStoreSpi.engineSetCertificateEntry(alias, cert);
    }

    /**
     * Deletes the entry identified by the given alias from this keystore.
     *
     * @param alias the alias name
     *
     * @exception KeyStoreException if the keystore has not been initialized,
     * or if the entry cannot be removed.
     */
    public final void deleteEntry(String alias)
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	keyStoreSpi.engineDeleteEntry(alias);
    }

    /**
     * Lists all the alias names of this keystore.
     *
     * @return enumeration of the alias names
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded).
     */
    public final Enumeration<String> aliases()
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	return keyStoreSpi.engineAliases();
    }

    /**
     * Checks if the given alias exists in this keystore.
     *
     * @param alias the alias name
     *
     * @return true if the alias exists, false otherwise
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded).
     */
    public final boolean containsAlias(String alias)
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	return keyStoreSpi.engineContainsAlias(alias);
    }

    /**
     * Retrieves the number of entries in this keystore.
     *
     * @return the number of entries in this keystore
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded).
     */
    public final int size()
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	return keyStoreSpi.engineSize();
    }

    /**
     * Returns true if the entry identified by the given alias
     * was created by a call to <code>setKeyEntry</code>,
     * or created by a call to <code>setEntry</code> with a
     * <code>PrivateKeyEntry</code> or a <code>SecretKeyEntry</code>.
     *
     * @param alias the alias for the keystore entry to be checked
     *
     * @return true if the entry identified by the given alias is a
     * key-related entry, false otherwise.
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded).
     */
    public final boolean isKeyEntry(String alias)
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	return keyStoreSpi.engineIsKeyEntry(alias);
    }

    /**
     * Returns true if the entry identified by the given alias
     * was created by a call to <code>setCertificateEntry</code>,
     * or created by a call to <code>setEntry</code> with a
     * <code>TrustedCertificateEntry</code>.
     *
     * @param alias the alias for the keystore entry to be checked
     *
     * @return true if the entry identified by the given alias contains a
     * trusted certificate, false otherwise.
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded).
     */
    public final boolean isCertificateEntry(String alias)
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	return keyStoreSpi.engineIsCertificateEntry(alias);
    }

    /**
     * Returns the (alias) name of the first keystore entry whose certificate
     * matches the given certificate.
     *
     * <p> This method attempts to match the given certificate with each
     * keystore entry. If the entry being considered was
     * created by a call to <code>setCertificateEntry</code>,
     * or created by a call to <code>setEntry</code> with a
     * <code>TrustedCertificateEntry</code>,
     * then the given certificate is compared to that entry's certificate.
     *
     * <p> If the entry being considered was
     * created by a call to <code>setKeyEntry</code>,
     * or created by a call to <code>setEntry</code> with a
     * <code>PrivateKeyEntry</code>,
     * then the given certificate is compared to the first
     * element of that entry's certificate chain.
     *
     * @param cert the certificate to match with.
     *
     * @return the alias name of the first entry with a matching certificate,
     * or null if no such entry exists in this keystore.
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded).
     */
    public final String getCertificateAlias(Certificate cert)
	throws KeyStoreException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	return keyStoreSpi.engineGetCertificateAlias(cert);
    }

    /**
     * Stores this keystore to the given output stream, and protects its
     * integrity with the given password.
     *
     * @param stream the output stream to which this keystore is written.
     * @param password the password to generate the keystore integrity check
     *
     * @exception KeyStoreException if the keystore has not been initialized
     * (loaded).
     * @exception IOException if there was an I/O problem with data
     * @exception NoSuchAlgorithmException if the appropriate data integrity
     * algorithm could not be found
     * @exception CertificateException if any of the certificates included in
     * the keystore data could not be stored
     */
    public final void store(OutputStream stream, char[] password)
	throws KeyStoreException, IOException, NoSuchAlgorithmException,
	    CertificateException
    {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	keyStoreSpi.engineStore(stream, password);
    }

    /**
     * Stores this keystore using the given <code>LoadStoreParameter</code>.
     *
     * @param param the <code>LoadStoreParameter</code>
     *		that specifies how to store the keystore,
     *		which may be <code>null</code>
     *
     * @exception IllegalArgumentException if the given
     *		<code>LoadStoreParameter</code>
     *		input is not recognized
     * @exception KeyStoreException if the keystore has not been initialized
     *		(loaded)
     * @exception IOException if there was an I/O problem with data
     * @exception NoSuchAlgorithmException if the appropriate data integrity
     *		algorithm could not be found
     * @exception CertificateException if any of the certificates included in
     *		the keystore data could not be stored
     *
     * @since 1.5
     */
    public final void store(LoadStoreParameter param)
		throws KeyStoreException, IOException,
		NoSuchAlgorithmException, CertificateException {
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	keyStoreSpi.engineStore(param);
    }

    /**
     * Loads this KeyStore from the given input stream.
     *
     * <p>A password may be given to unlock the keystore
     * (e.g. the keystore resides on a hardware token device),
     * or to check the integrity of the keystore data.
     * If a password is not given for integrity checking,
     * then integrity checking is not performed.
     *
     * <p>In order to create an empty keystore, or if the keystore cannot
     * be initialized from a stream, pass <code>null</code>
     * as the <code>stream</code> argument.
     *
     * <p> Note that if this keystore has already been loaded, it is
     * reinitialized and loaded again from the given input stream.
     *
     * @param stream the input stream from which the keystore is loaded,
     * or <code>null</code>
     * @param password the password used to check the integrity of
     * the keystore, the password used to unlock the keystore,
     * or <code>null</code>
     *
     * @exception IOException if there is an I/O or format problem with the
     * keystore data, if a password is required but not given,
     * or if the given password was incorrect. If the error is due to a
     * wrong password, the {@link Throwable#getCause cause} of the 
     * <code>IOException</code> should be an 
     * <code>UnrecoverableKeyException</code>
     * @exception NoSuchAlgorithmException if the algorithm used to check
     * the integrity of the keystore cannot be found
     * @exception CertificateException if any of the certificates in the
     * keystore could not be loaded
     */
    public final void load(InputStream stream, char[] password)
	throws IOException, NoSuchAlgorithmException, CertificateException
    {
	keyStoreSpi.engineLoad(stream, password);
	initialized = true;
    }

    /**
     * Loads this keystore using the given <code>LoadStoreParameter</code>.
     *
     * <p> Note that if this KeyStore has already been loaded, it is
     * reinitialized and loaded again from the given parameter.
     *
     * @param param the <code>LoadStoreParameter</code>
     *		that specifies how to load the keystore,
     *		which may be <code>null</code>
     *
     * @exception IllegalArgumentException if the given
     *		<code>LoadStoreParameter</code>
     *		input is not recognized
     * @exception IOException if there is an I/O or format problem with the
     *		keystore data. If the error is due to an incorrect 
     *         <code>ProtectionParameter</code> (e.g. wrong password)
     *         the {@link Throwable#getCause cause} of the 
     *         <code>IOException</code> should be an 
     *         <code>UnrecoverableKeyException</code>
     * @exception NoSuchAlgorithmException if the algorithm used to check
     *		the integrity of the keystore cannot be found
     * @exception CertificateException if any of the certificates in the
     *		keystore could not be loaded
     *
     * @since 1.5
     */
    public final void load(LoadStoreParameter param)
		throws IOException, NoSuchAlgorithmException,
		CertificateException {

	keyStoreSpi.engineLoad(param);
	initialized = true;
    }

    /**
     * Gets a keystore <code>Entry</code> for the specified alias
     * with the specified protection parameter.
     *
     * @param alias get the keystore <code>Entry</code> for this alias
     * @param protParam the <code>ProtectionParameter</code>
     *		used to protect the <code>Entry</code>,
     *		which may be <code>null</code>
     *
     * @return the keystore <code>Entry</code> for the specified alias,
     *		or <code>null</code> if there is no such entry
     *
     * @exception NullPointerException if
     *		<code>alias</code> is <code>null</code>
     * @exception NoSuchAlgorithmException if the algorithm for recovering the
     *		entry cannot be found
     * @exception UnrecoverableEntryException if the specified
     *		<code>protParam</code> were insufficient or invalid
     * @exception UnrecoverableKeyException if the entry is a 
     *          <code>PrivateKeyEntry</code> or <code>SecretKeyEntry</code>
     *          and the specified <code>protParam</code> does not contain
     *          the information needed to recover the key (e.g. wrong password)
     * @exception KeyStoreException if the keystore has not been initialized
     *		(loaded).
     * @see #setEntry(String, KeyStore.Entry, KeyStore.ProtectionParameter)
     *
     * @since 1.5
     */
    public final Entry getEntry(String alias, ProtectionParameter protParam)
    		throws NoSuchAlgorithmException, UnrecoverableEntryException,
		KeyStoreException {

	if (alias == null) {
	    throw new NullPointerException("invalid null input");
	}
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	return keyStoreSpi.engineGetEntry(alias, protParam);
    }

    /**
     * Saves a keystore <code>Entry</code> under the specified alias.
     * The protection parameter is used to protect the
     * <code>Entry</code>.
     *
     * <p> If an entry already exists for the specified alias,
     * it is overridden.
     *
     * @param alias save the keystore <code>Entry</code> under this alias
     * @param entry the <code>Entry</code> to save
     * @param protParam the <code>ProtectionParameter</code>
     *		used to protect the <code>Entry</code>,
     *		which may be <code>null</code>
     *
     * @exception NullPointerException if
     *		<code>alias</code> or <code>entry</code>
     *		is <code>null</code>
     * @exception KeyStoreException if the keystore has not been initialized
     *		(loaded), or if this operation fails for some other reason
     *
     * @see #getEntry(String, KeyStore.ProtectionParameter)
     *
     * @since 1.5
     */
    public final void setEntry(String alias, Entry entry,
			ProtectionParameter protParam)
		throws KeyStoreException {
	if (alias == null || entry == null) {
	    throw new NullPointerException("invalid null input");
	}
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	keyStoreSpi.engineSetEntry(alias, entry, protParam);
    }

    /**
     * Determines if the keystore <code>Entry</code> for the specified
     * <code>alias</code> is an instance or subclass of the specified
     * <code>entryClass</code>.
     *
     * @param alias the alias name
     * @param entryClass the entry class 
     *
     * @return true if the keystore <code>Entry</code> for the specified
     *		<code>alias</code> is an instance or subclass of the
     *		specified <code>entryClass</code>, false otherwise
     *
     * @exception NullPointerException if
     *		<code>alias</code> or <code>entryClass</code>
     *		is <code>null</code>
     * @exception KeyStoreException if the keystore has not been
     *		initialized (loaded)
     *
     * @since 1.5
     */
    public final boolean
	entryInstanceOf(String alias,
			Class<? extends KeyStore.Entry> entryClass)
	throws KeyStoreException
    {

	if (alias == null || entryClass == null) {
	    throw new NullPointerException("invalid null input");
	}
	if (!initialized) {
	    throw new KeyStoreException("Uninitialized keystore");
	}
	return keyStoreSpi.engineEntryInstanceOf(alias, entryClass);
    }
    
    /**
     * A description of a to-be-instantiated KeyStore object.
     *
     * <p>An instance of this class encapsulates the information needed to
     * instantiate and initialize a KeyStore object. That process is
     * triggered when the {@linkplain #getKeyStore} method is called.
     *
     * <p>This makes it possible to decouple configuration from KeyStore
     * object creation and e.g. delay a password prompt until it is
     * needed.
     *
     * @see KeyStore
     * @see javax.net.ssl.KeyStoreBuilderParameters
     * @since 1.5
     */
    public static abstract class Builder {

	// maximum times to try the callbackhandler if the password is wrong
	static final int MAX_CALLBACK_TRIES = 3;
	
	/**
	 * Construct a new Builder.
	 */
	protected Builder() {
	    // empty
	}

	/**
	 * Returns the KeyStore described by this object.
	 *
	 * @exception KeyStoreException if an error occured during the
	 *   operation, for example if the KeyStore could not be
	 *   instantiated or loaded
	 */
	public abstract KeyStore getKeyStore() throws KeyStoreException;

	/**
	 * Returns the ProtectionParameters that should be used to obtain
	 * the {@link KeyStore.Entry Entry} with the given alias.
	 * The <code>getKeyStore</code> method must be invoked before this
	 * method may be called.
	 *
	 * @return the ProtectionParameters that should be used to obtain
	 *   the {@link KeyStore.Entry Entry} with the given alias.
	 * @param alias the alias of the KeyStore entry
	 * @throws NullPointerException if alias is null
	 * @throws KeyStoreException if an error occured during the
	 *   operation
	 * @throws IllegalStateException if the getKeyStore method has
	 *   not been invoked prior to calling this method
	 */
	public abstract ProtectionParameter getProtectionParameter(String alias)
	    throws KeyStoreException;

	/**
	 * Returns a new Builder that encapsulates the given KeyStore.
	 * The {@linkplain #getKeyStore} method of the returned object 
	 * will return <code>keyStore</code>, the {@linkplain 
	 * #getProtectionParameter getProtectionParameter()} method will 
	 * return <code>protectionParameters</code>.
         *
	 * <p> This is useful if an existing KeyStore object needs to be
	 * used with Builder-based APIs.
	 *
	 * @return a new Builder object
	 * @param keyStore the KeyStore to be encapsulated
	 * @param protectionParameter the ProtectionParameter used to
	 *   protect the KeyStore entries
	 * @throws NullPointerException if keyStore or
	 *   protectionParameters is null
	 * @throws IllegalArgumentException if the keyStore has not been
	 *   initialized
	 */
	public static Builder newInstance(final KeyStore keyStore,
		final ProtectionParameter protectionParameter) {
	    if ((keyStore == null) || (protectionParameter == null)) {
		throw new NullPointerException();
	    }
	    if (keyStore.initialized == false) {
		throw new IllegalArgumentException("KeyStore not initialized");
	    }
	    return new Builder() {
		private volatile boolean getCalled;
		
		public KeyStore getKeyStore() {
		    getCalled = true;
		    return keyStore;
		}
		
		public ProtectionParameter getProtectionParameter(String alias)
		{
		    if (alias == null) {
			throw new NullPointerException();
		    }
		    if (getCalled == false) {
			throw new IllegalStateException
			    ("getKeyStore() must be called first");
		    }
		    return protectionParameter;
		}
	    };
	}

	/**
	 * Returns a new Builder object.
	 *
	 * <p>The first call to the {@link #getKeyStore} method on the returned
	 * builder will create a KeyStore of type <code>type</code> and call
	 * its {@link KeyStore#load load()} method. 
	 * The <code>inputStream</code> argument is constructed from
	 * <code>file</code>. 
	 * If <code>protection</code> is a
	 * <code>PasswordProtection</code>, the password is obtained by
	 * calling the <code>getPassword</code> method.
	 * Otherwise, if <code>protection</code> is a 
	 * <code>CallbackHandlerProtection</code>, the password is obtained
	 * by invoking the CallbackHandler.
	 *
	 * <p>Subsequent calls to {@link #getKeyStore} return the same object 
	 * as the initial call. If the initial call to failed with a
	 * KeyStoreException, subsequent calls also throw a 
	 * KeyStoreException.
	 *
	 * <p>The KeyStore is instantiated from <code>provider</code> if
	 * non-null. Otherwise, all installed providers are searched.
	 *
	 * <p>Calls to {@link #getProtectionParameter getProtectionParameter()}
	 * will return a {@link KeyStore.PasswordProtection PasswordProtection}
	 * object encapsulating the password that was used to invoke the
	 * <code>load</code> method.
	 *
	 * <p><em>Note</em> that the {@link #getKeyStore} method is executed 
	 * within the {@link AccessControlContext} of the code invoking this 
	 * method.
	 *
	 * @return a new Builder object
	 * @param type the type of KeyStore to be constructed
	 * @param provider the provider from which the KeyStore is to
	 *   be instantiated (or null)
	 * @param file the File that contains the KeyStore data
	 * @param protection the ProtectionParameter securing the KeyStore data
	 * @throws NullPointerException if type, file or protection is null
	 * @throws IllegalArgumentException if protection is not an instance
	 *   of either PasswordProtection or CallbackHandlerProtection; or
	 *   if file does not exist or does not refer to a normal file
	 */
	public static Builder newInstance(String type, Provider provider, 
		File file, ProtectionParameter protection) {
	    if ((type == null) || (file == null) || (protection == null)) {
		throw new NullPointerException();
	    }
	    if ((protection instanceof PasswordProtection == false) &&
		(protection instanceof CallbackHandlerProtection == false)) {
		throw new IllegalArgumentException
		("Protection must be PasswordProtection or " +
		 "CallbackHandlerProtection");
	    }
	    if (file.isFile() == false) {
		throw new IllegalArgumentException
		    ("File does not exist or it does not refer " +
		     "to a normal file: " + file);
	    }
	    return new FileBuilder(type, provider, file, protection, 
		AccessController.getContext());
	}
	
	private static final class FileBuilder extends Builder {
	    
	    private final String type;
	    private final Provider provider;
	    private final File file;
	    private ProtectionParameter protection;
	    private ProtectionParameter keyProtection;
	    private final AccessControlContext context;
	    
	    private KeyStore keyStore;
	    
	    private Throwable oldException;
	    
	    FileBuilder(String type, Provider provider, File file, 
		    ProtectionParameter protection, 
		    AccessControlContext context) {
		this.type = type;
		this.provider = provider;
		this.file = file;
		this.protection = protection;
		this.context = context;
	    }
	    
	    public synchronized KeyStore getKeyStore() throws KeyStoreException
	    {
		if (keyStore != null) {
		    return keyStore;
		}
		if (oldException != null) {
		    throw new KeyStoreException
			("Previous KeyStore instantiation failed",
			 oldException);
		}
		PrivilegedExceptionAction action = 
			new PrivilegedExceptionAction() {
		    public Object run() throws Exception {
			if (protection instanceof CallbackHandlerProtection == false) {
			    return run0();
			}
			// when using a CallbackHandler,
			// reprompt if the password is wrong
			int tries = 0;
			while (true) {
			    tries++;
			    try {
				return run0();
			    } catch (IOException e) {
				if ((tries < MAX_CALLBACK_TRIES)
					&& (e.getCause() instanceof UnrecoverableKeyException)) {
				    continue;
				}
				throw e;
			    }
			}
		    }
		    public Object run0() throws Exception {
			KeyStore ks;
			if (provider == null) {
			    ks = KeyStore.getInstance(type);
			} else {
			    ks = KeyStore.getInstance(type, provider);
			}
			InputStream in = null;
			char[] password = null;
			try {
			    in = new FileInputStream(file);
			    if (protection instanceof PasswordProtection) {
				password = 
				((PasswordProtection)protection).getPassword();
				keyProtection = protection;
			    } else {
				CallbackHandler handler = 
				    ((CallbackHandlerProtection)protection)
				    .getCallbackHandler();
				PasswordCallback callback = new PasswordCallback
				    ("Password for keystore " + file.getName(), 
				    false);
				handler.handle(new Callback[] {callback});
				password = callback.getPassword();
				if (password == null) {
				    throw new KeyStoreException("No password" +
								" provided");
				}
				callback.clearPassword();
				keyProtection = new PasswordProtection(password);
			    }
			    ks.load(in, password);
			    return ks;
			} finally {
			    if (in != null) {
				in.close();
			    }
			}
		    }
		};
		try {
		    keyStore = (KeyStore)AccessController.doPrivileged
							(action, context);
		    return keyStore;
		} catch (PrivilegedActionException e) {
		    oldException = e.getCause();
		    throw new KeyStoreException
			("KeyStore instantiation failed", oldException);
		}
	    }
	    
	    public synchronized ProtectionParameter 
			getProtectionParameter(String alias) {
		if (alias == null) {
		    throw new NullPointerException();
		}
		if (keyStore == null) {
		    throw new IllegalStateException
			("getKeyStore() must be called first");
		}
		return keyProtection;
	    }
	}
	
	/**
	 * Returns a new Builder object.
	 *
	 * <p>Each call to the {@link #getKeyStore} method on the returned
	 * builder will return a new KeyStore object of type <code>type</code>.
	 * Its {@link KeyStore#load(KeyStore.LoadStoreParameter) load()} 
	 * method is invoked using a
	 * <code>LoadStoreParameter</code> that encapsulates 
	 * <code>protection</code>.
	 *
	 * <p>The KeyStore is instantiated from <code>provider</code> if
	 * non-null. Otherwise, all installed providers are searched.
	 *
	 * <p>Calls to {@link #getProtectionParameter getProtectionParameter()}
	 * will return <code>protection</code>.
	 *
	 * <p><em>Note</em> that the {@link #getKeyStore} method is executed 
	 * within the {@link AccessControlContext} of the code invoking this 
	 * method.
	 *
	 * @return a new Builder object
	 * @param type the type of KeyStore to be constructed
	 * @param provider the provider from which the KeyStore is to
	 *   be instantiated (or null)
	 * @param protection the ProtectionParameter securing the Keystore
	 * @throws NullPointerException if type or protection is null
	 */
	public static Builder newInstance(final String type, 
		final Provider provider, final ProtectionParameter protection) {
	    if ((type == null) || (protection == null)) {
		throw new NullPointerException();
	    }
	    final AccessControlContext context = AccessController.getContext();
	    return new Builder() {
		private volatile boolean getCalled;
		private IOException oldException;
		
		private final PrivilegedExceptionAction action
		= new PrivilegedExceptionAction() {
		    
		    public Object run() throws Exception {
			KeyStore ks;
			if (provider == null) {
			    ks = KeyStore.getInstance(type);
			} else {
			    ks = KeyStore.getInstance(type, provider);
			}
			LoadStoreParameter param = new SimpleLoadStoreParameter(protection);
			if (protection instanceof CallbackHandlerProtection == false) {
			    ks.load(param);
			} else {
			    // when using a CallbackHandler,
			    // reprompt if the password is wrong
			    int tries = 0;
			    while (true) {
				tries++;
				try {
				    ks.load(param);
				    break;
				} catch (IOException e) {
				    if (e.getCause() instanceof UnrecoverableKeyException) {
					if (tries < MAX_CALLBACK_TRIES) {
					    continue;
					} else {
					    oldException = e;
					}
				    }
				    throw e;
				}
			    }
			}
			getCalled = true;
			return ks;
		    }
		};
		
		public synchronized KeyStore getKeyStore()
			throws KeyStoreException {
		    if (oldException != null) {
			throw new KeyStoreException
			    ("Previous KeyStore instantiation failed",
			     oldException);
		    }
		    try {
			return (KeyStore)AccessController.doPrivileged(action);
		    } catch (PrivilegedActionException e) {
			Throwable cause = e.getCause();
			throw new KeyStoreException
			    ("KeyStore instantiation failed", cause);
		    }
		}
		
		public ProtectionParameter getProtectionParameter(String alias)
		{
		    if (alias == null) {
			throw new NullPointerException();
		    }
		    if (getCalled == false) {
			throw new IllegalStateException
			    ("getKeyStore() must be called first");
		    }
		    return protection;
		}
	    };
	}

    }
    
    static class SimpleLoadStoreParameter implements LoadStoreParameter {
	
	private final ProtectionParameter protection;
	
	SimpleLoadStoreParameter(ProtectionParameter protection) {
	    this.protection = protection;
	}
	
	public ProtectionParameter getProtectionParameter() {
	    return protection;
	}
    }
    
}