content: /*
   * 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 java.security;
  
  import java.io.*;
  import java.net.URI;
  import java.security.cert.Certificate;
  import java.security.cert.X509Certificate;
  import java.security.cert.CertificateException;
  import java.security.spec.AlgorithmParameterSpec;
  import java.util.*;
  import javax.crypto.SecretKey;
  
  import javax.security.auth.DestroyFailedException;
  import javax.security.auth.callback.*;
  
  /**
   * This class represents a storage facility for cryptographic
   * keys and certificates.
   *
   * <p> A {@code KeyStore} manages different types of entries.
   * Each type of entry implements the {@code KeyStore.Entry} interface.
   * Three basic {@code KeyStore.Entry} implementations are provided:
   *
   * <ul>
   * <li><b>KeyStore.PrivateKeyEntry</b>
   * <p> This type of entry holds a cryptographic {@code PrivateKey},
   * 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},
   * 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}
   * 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.
   *
   * <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(InputStream, char[]) loaded}.
   * <pre>
   *    KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
   *
   *    // get user password and file input stream
   *    char[] password = getPassword();
   *
   *    try (FileInputStream fis = new FileInputStream("keyStoreName")) {
   *        ks.load(fis, password);
   *    }
   * </pre>
   *
   * To create an empty keystore using the above {@code load} method,
   * pass {@code null} as the {@code InputStream} 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>
   *    KeyStore.ProtectionParameter protParam =
   *        new KeyStore.PasswordProtection(password);
   *
   *    // get my private key
   *    KeyStore.PrivateKeyEntry pkEntry = (KeyStore.PrivateKeyEntry)
   *        ks.getEntry("privateKeyAlias", protParam);
   *    PrivateKey myPrivateKey = pkEntry.getPrivateKey();
   *
   *    // save my secret key
   *    javax.crypto.SecretKey mySecretKey;
   *    KeyStore.SecretKeyEntry skEntry =
   *        new KeyStore.SecretKeyEntry(mySecretKey);
   *    ks.setEntry("secretKeyAlias", skEntry, protParam);
   *
   *    // store away the keystore
   *    try (FileOutputStream fos = new FileOutputStream("newKeyStoreName")) {
   *        ks.store(fos, password);
   *    }
   * </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.
   *
   * <p> Android provides the following <code>KeyStore</code> types:
   * <table>
   *   <thead>
   *     <tr>
   *       <th>Algorithm</th>
   *       <th>Supported API Levels</th>
   *     </tr>
   *   </thead>
   *   <tbody>
   *     <tr>
   *       <td>AndroidCAStore</td>
   *       <td>14+</td>
   *     </tr>
   *     <tr>
   *       <td>AndroidKeyStore</td>
   *       <td>18+</td>
   *     </tr>
   *     <tr class="deprecated">
   *       <td>BCPKCS12</td>
   *       <td>1-8</td>
   *     </tr>
   *     <tr>
   *       <td>BKS</td>
   *       <td>1+</td>
   *     </tr>
   *     <tr>
   *       <td>BouncyCastle</td>
   *       <td>1+</td>
   *     </tr>
   *     <tr>
   *       <td>PKCS12</td>
   *       <td>1+</td>
   *     </tr>
   *     <tr class="deprecated">
   *       <td>PKCS12-DEF</td>
   *       <td>1-8</td>
   *     </tr>
   *   </tbody>
   * </table>
   *
   * These types are described in the <a href=
   * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyStore">
   * KeyStore section</a> of the
   * Java Cryptography Architecture Standard Algorithm Name Documentation.
   *
   * @author Jan Luehe
   *
   * @see PrivateKey
   * @see SecretKey
   * @see Certificate
   *
   * @since 1.2
   */
  
  public class KeyStore {
  
      // BEGIN Android-removed: this debugging mechanism is not supported in Android.
      /*
      private static final Debug pdebug =
                          Debug.getInstance("provider", "Provider");
      private static final boolean skipDebug =
          Debug.isOn("engine=") && !Debug.isOn("keystore");
      */
      // END Android-removed: this debugging mechanism is not supported in Android.
  
      /*
       * 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}
       * {@link #load(LoadStoreParameter) load}
       * and
       * {@link #store(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}
       * 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}).
       *
       * @since 1.5
       */
      public static interface ProtectionParameter { }
  
      /**
       * A password-based implementation of {@code ProtectionParameter}.
       *
       * @since 1.5
       */
      public static class PasswordProtection implements
                  ProtectionParameter, javax.security.auth.Destroyable {
  
          private final char[] password;
          private final String protectionAlgorithm;
          private final AlgorithmParameterSpec protectionParameters;
          private volatile boolean destroyed = false;
  
          /**
           * Creates a password parameter.
           *
           * <p> The specified {@code password} is cloned before it is stored
           * in the new {@code PasswordProtection} object.
           *
           * @param password the password, which may be {@code null}
           */
          public PasswordProtection(char[] password) {
              this.password = (password == null) ? null : password.clone();
              this.protectionAlgorithm = null;
              this.protectionParameters = null;
          }
  
          /**
           * Creates a password parameter and specifies the protection algorithm
           * and associated parameters to use when encrypting a keystore entry.
           * <p>
           * The specified {@code password} is cloned before it is stored in the
           * new {@code PasswordProtection} object.
           *
           * @param password the password, which may be {@code null}
           * @param protectionAlgorithm the encryption algorithm name, for
           *     example, {@code PBEWithHmacSHA256AndAES_256}.
           *     See the Cipher section in the <a href=
           * "{@docRoot}/../technotes/guides/security/StandardNames.html#Cipher">
           * Java Cryptography Architecture Standard Algorithm Name
           * Documentation</a>
           *     for information about standard encryption algorithm names.
           * @param protectionParameters the encryption algorithm parameter
           *     specification, which may be {@code null}
           * @exception NullPointerException if {@code protectionAlgorithm} is
           *     {@code null}
           *
           * @since 1.8
           */
          public PasswordProtection(char[] password, String protectionAlgorithm,
              AlgorithmParameterSpec protectionParameters) {
              if (protectionAlgorithm == null) {
                  throw new NullPointerException("invalid null input");
              }
              this.password = (password == null) ? null : password.clone();
              this.protectionAlgorithm = protectionAlgorithm;
              this.protectionParameters = protectionParameters;
          }
  
          /**
           * Gets the name of the protection algorithm.
           * If none was set then the keystore provider will use its default
           * protection algorithm. The name of the default protection algorithm
           * for a given keystore type is set using the
           * {@code 'keystore.<type>.keyProtectionAlgorithm'} security property.
           * For example, the
           * {@code keystore.PKCS12.keyProtectionAlgorithm} property stores the
           * name of the default key protection algorithm used for PKCS12
           * keystores. If the security property is not set, an
           * implementation-specific algorithm will be used.
           *
           * @return the algorithm name, or {@code null} if none was set
           *
           * @since 1.8
           */
          public String getProtectionAlgorithm() {
              return protectionAlgorithm;
          }
  
          /**
           * Gets the parameters supplied for the protection algorithm.
           *
           * @return the algorithm parameter specification, or {@code  null},
           *     if none was set
           *
           * @since 1.8
           */
          public AlgorithmParameterSpec getProtectionParameters() {
              return protectionParameters;
          }
  
          /**
           * 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}
           * @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 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} entry types.
       *
       * @since 1.5
       */
      public static interface Entry {
  
          /**
           * Retrieves the attributes associated with an entry.
           * <p>
           * The default implementation returns an empty {@code Set}.
           *
           * @return an unmodifiable {@code Set} of attributes, possibly empty
           *
           * @since 1.8
           */
          public default Set<Attribute> getAttributes() {
              return Collections.<Attribute>emptySet();
          }
  
          /**
           * An attribute associated with a keystore entry.
           * It comprises a name and one or more values.
           *
           * @since 1.8
           */
          public interface Attribute {
              /**
               * Returns the attribute's name.
               *
               * @return the attribute name
               */
              public String getName();
  
              /**
               * Returns the attribute's value.
               * Multi-valued attributes encode their values as a single string.
               *
               * @return the attribute value
               */
              public String getValue();
          }
      }
  
      /**
       * A {@code KeyStore} entry that holds a {@code PrivateKey}
       * and corresponding certificate chain.
       *
       * @since 1.5
       */
      public static final class PrivateKeyEntry implements Entry {
  
          private final PrivateKey privKey;
          private final Certificate[] chain;
          private final Set<Attribute> attributes;
  
          /**
           * Constructs a {@code PrivateKeyEntry} with a
           * {@code PrivateKey} and corresponding certificate chain.
           *
           * <p> The specified {@code chain} is cloned before it is stored
           * in the new {@code PrivateKeyEntry} object.
           *
           * @param privateKey the {@code PrivateKey}
           * @param chain an array of {@code Certificate}s
           *      representing the certificate chain.
           *      The chain must be ordered and contain a
           *      {@code Certificate} at index 0
           *      corresponding to the private key.
           *
           * @exception NullPointerException if
           *      {@code privateKey} or {@code chain}
           *      is {@code null}
           * @exception IllegalArgumentException if the specified chain has a
           *      length of 0, if the specified chain does not contain
           *      {@code Certificate}s of the same type,
           *      or if the {@code PrivateKey} algorithm
           *      does not match the algorithm of the {@code PublicKey}
           *      in the end entity {@code Certificate} (at index 0)
           */
          public PrivateKeyEntry(PrivateKey privateKey, Certificate[] chain) {
              this(privateKey, chain, Collections.<Attribute>emptySet());
          }
  
          /**
           * Constructs a {@code PrivateKeyEntry} with a {@code PrivateKey} and
           * corresponding certificate chain and associated entry attributes.
           *
           * <p> The specified {@code chain} and {@code attributes} are cloned
           * before they are stored in the new {@code PrivateKeyEntry} object.
           *
           * @param privateKey the {@code PrivateKey}
           * @param chain an array of {@code Certificate}s
           *      representing the certificate chain.
           *      The chain must be ordered and contain a
           *      {@code Certificate} at index 0
           *      corresponding to the private key.
           * @param attributes the attributes
           *
           * @exception NullPointerException if {@code privateKey}, {@code chain}
           *      or {@code attributes} is {@code null}
           * @exception IllegalArgumentException if the specified chain has a
           *      length of 0, if the specified chain does not contain
           *      {@code Certificate}s of the same type,
           *      or if the {@code PrivateKey} algorithm
           *      does not match the algorithm of the {@code PublicKey}
           *      in the end entity {@code Certificate} (at index 0)
           *
           * @since 1.8
           */
          public PrivateKeyEntry(PrivateKey privateKey, Certificate[] chain,
             Set<Attribute> attributes) {
  
              if (privateKey == null || chain == null || attributes == null) {
                  throw new NullPointerException("invalid null input");
              }
              if (chain.length == 0) {
                  throw new IllegalArgumentException
                                  ("invalid zero-length input chain");
              }
  
              Certificate[] clonedChain = 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;
              }
  
              this.attributes =
                  Collections.unmodifiableSet(new HashSet<>(attributes));
          }
  
          /**
           * Gets the {@code PrivateKey} from this entry.
           *
           * @return the {@code PrivateKey} from this entry
           */
          public PrivateKey getPrivateKey() {
              return privKey;
          }
  
          /**
           * Gets the {@code Certificate} chain from this entry.
           *
           * <p> The stored chain is cloned before being returned.
           *
           * @return an array of {@code Certificate}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[]}.
           */
          public Certificate[] getCertificateChain() {
              return chain.clone();
          }
  
          /**
           * Gets the end entity {@code Certificate}
           * from the certificate chain in this entry.
           *
           * @return the end entity {@code Certificate} (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}.
           */
          public Certificate getCertificate() {
              return chain[0];
          }
  
          /**
           * Retrieves the attributes associated with an entry.
           * <p>
           *
           * @return an unmodifiable {@code Set} of attributes, possibly empty
           *
           * @since 1.8
           */
          @Override
          public Set<Attribute> getAttributes() {
              return attributes;
          }
  
          /**
           * 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} entry that holds a {@code SecretKey}.
       *
       * @since 1.5
       */
      public static final class SecretKeyEntry implements Entry {
  
          private final SecretKey sKey;
          private final Set<Attribute> attributes;
  
          /**
           * Constructs a {@code SecretKeyEntry} with a
           * {@code SecretKey}.
           *
           * @param secretKey the {@code SecretKey}
           *
           * @exception NullPointerException if {@code secretKey}
           *      is {@code null}
           */
          public SecretKeyEntry(SecretKey secretKey) {
              if (secretKey == null) {
                  throw new NullPointerException("invalid null input");
              }
              this.sKey = secretKey;
              this.attributes = Collections.<Attribute>emptySet();
          }
  
          /**
           * Constructs a {@code SecretKeyEntry} with a {@code SecretKey} and
           * associated entry attributes.
           *
           * <p> The specified {@code attributes} is cloned before it is stored
           * in the new {@code SecretKeyEntry} object.
           *
           * @param secretKey the {@code SecretKey}
           * @param attributes the attributes
           *
           * @exception NullPointerException if {@code secretKey} or
           *     {@code attributes} is {@code null}
           *
           * @since 1.8
           */
          public SecretKeyEntry(SecretKey secretKey, Set<Attribute> attributes) {
  
              if (secretKey == null || attributes == null) {
                  throw new NullPointerException("invalid null input");
              }
              this.sKey = secretKey;
              this.attributes =
                  Collections.unmodifiableSet(new HashSet<>(attributes));
          }
  
          /**
           * Gets the {@code SecretKey} from this entry.
           *
           * @return the {@code SecretKey} from this entry
           */
          public SecretKey getSecretKey() {
              return sKey;
          }
  
          /**
           * Retrieves the attributes associated with an entry.
           * <p>
           *
           * @return an unmodifiable {@code Set} of attributes, possibly empty
           *
           * @since 1.8
           */
          @Override
          public Set<Attribute> getAttributes() {
              return attributes;
          }
  
          /**
           * 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} entry that holds a trusted
       * {@code Certificate}.
       *
       * @since 1.5
       */
      public static final class TrustedCertificateEntry implements Entry {
  
          private final Certificate cert;
          private final Set<Attribute> attributes;
  
          /**
           * Constructs a {@code TrustedCertificateEntry} with a
           * trusted {@code Certificate}.
           *
           * @param trustedCert the trusted {@code Certificate}
           *
           * @exception NullPointerException if
           *      {@code trustedCert} is {@code null}
           */
          public TrustedCertificateEntry(Certificate trustedCert) {
              if (trustedCert == null) {
                  throw new NullPointerException("invalid null input");
              }
              this.cert = trustedCert;
              this.attributes = Collections.<Attribute>emptySet();
          }
  
          /**
           * Constructs a {@code TrustedCertificateEntry} with a
           * trusted {@code Certificate} and associated entry attributes.
           *
           * <p> The specified {@code attributes} is cloned before it is stored
           * in the new {@code TrustedCertificateEntry} object.
           *
           * @param trustedCert the trusted {@code Certificate}
           * @param attributes the attributes
           *
           * @exception NullPointerException if {@code trustedCert} or
           *     {@code attributes} is {@code null}
           *
           * @since 1.8
           */
          public TrustedCertificateEntry(Certificate trustedCert,
             Set<Attribute> attributes) {
              if (trustedCert == null || attributes == null) {
                  throw new NullPointerException("invalid null input");
              }
              this.cert = trustedCert;
              this.attributes =
                  Collections.unmodifiableSet(new HashSet<>(attributes));
          }
  
          /**
           * Gets the trusted {@code Certficate} from this entry.
           *
           * @return the trusted {@code Certificate} from this entry
           */
          public Certificate getTrustedCertificate() {
              return cert;
          }
  
          /**
           * Retrieves the attributes associated with an entry.
           * <p>
           *
           * @return an unmodifiable {@code Set} of attributes, possibly empty
           *
           * @since 1.8
           */
          @Override
          public Set<Attribute> getAttributes() {
              return attributes;
          }
  
          /**
           * 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;
  
          // BEGIN Android-removed: this debugging mechanism is not supported in Android.
          /*
          if (!skipDebug && pdebug != null) {
              pdebug.println("KeyStore." + type.toUpperCase() + " type from: " +
                  this.provider.getName());
          }
          */
          // END Android-removed: this debugging mechanism is not supported in Android.
      }
  
      /**
       * 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 the KeyStore section in the <a href=
       * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyStore">
       * Java Cryptography Architecture Standard Algorithm Name Documentation</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 the KeyStore section in the <a href=
       * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyStore">
       * Java Cryptography Architecture Standard Algorithm Name Documentation</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 the KeyStore section in the <a href=
       * "{@docRoot}/../technotes/guides/security/StandardNames.html#KeyStore">
       * Java Cryptography Architecture Standard Algorithm Name Documentation</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 by the
       * {@code keystore.type} security property, or the string
       * {@literal "jks"} (acronym for {@literal "Java keystore"})
       * if no such property exists.
       *
       * <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} 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
       * {@code keystore.type} security property to the desired keystore type.
       *
       * @return the default keystore type as specified by the
       * {@code keystore.type} security property, or the string {@literal "jks"}
       * if no such property exists.
       * @see Security security properties
       */
      public final static String getDefaultType() {
          String kstype;
          kstype = AccessController.doPrivileged(new PrivilegedAction<String>() {
              public String 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},
       * or by a call to {@code setEntry} with a
       * {@code PrivateKeyEntry} or {@code SecretKeyEntry}.
       *
       * @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},
       * or by a call to {@code setEntry} with a
       * {@code PrivateKeyEntry}.
       *
       * @param alias the alias name
       *
       * @return the certificate chain (ordered with the user's certificate first
       * followed by zero or more certificate authorities), 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},
       * or created by a call to {@code setEntry} with a
       * {@code TrustedCertificateEntry},
       * 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},
       * or created by a call to {@code setEntry} with a
       * {@code PrivateKeyEntry},
       * 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},
       * 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}).
       *
       * @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}, it must be accompanied by a
       * certificate chain certifying the corresponding public key. If the
       * underlying keystore implementation is of type {@code jks},
       * {@code key} must be encoded as an
       * {@code EncryptedPrivateKeyInfo} 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}).
       *
       * @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},
       * or created by a call to {@code setEntry} with a
       * {@code TrustedCertificateEntry},
       * 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},
       * or created by a call to {@code setEntry} with a
       * {@code PrivateKeyEntry} or a {@code SecretKeyEntry}.
       *
       * @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},
       * or created by a call to {@code setEntry} with a
       * {@code TrustedCertificateEntry}.
       *
       * @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},
       * or created by a call to {@code setEntry} with a
       * {@code TrustedCertificateEntry},
       * 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},
       * or created by a call to {@code setEntry} with a
       * {@code PrivateKeyEntry},
       * 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}.
       *
       * @param param the {@code LoadStoreParameter}
       *          that specifies how to store the keystore,
       *          which may be {@code null}
       *
       * @exception IllegalArgumentException if the given
       *          {@code LoadStoreParameter}
       *          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}
       * as the {@code stream} 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}
       * @param password the password used to check the integrity of
       * the keystore, the password used to unlock the keystore,
       * or {@code null}
       *
       * @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} should be an
       * {@code UnrecoverableKeyException}
       * @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}.
       *
       * <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}
       *          that specifies how to load the keystore,
       *          which may be {@code null}
       *
       * @exception IllegalArgumentException if the given
       *          {@code LoadStoreParameter}
       *          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} (e.g. wrong password)
       *         the {@link Throwable#getCause cause} of the
       *         {@code IOException} should be an
       *         {@code UnrecoverableKeyException}
       * @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} for the specified alias
       * with the specified protection parameter.
       *
       * @param alias get the keystore {@code Entry} for this alias
       * @param protParam the {@code ProtectionParameter}
       *          used to protect the {@code Entry},
       *          which may be {@code null}
       *
       * @return the keystore {@code Entry} for the specified alias,
       *          or {@code null} if there is no such entry
       *
       * @exception NullPointerException if
       *          {@code alias} is {@code null}
       * @exception NoSuchAlgorithmException if the algorithm for recovering the
       *          entry cannot be found
       * @exception UnrecoverableEntryException if the specified
       *          {@code protParam} were insufficient or invalid
       * @exception UnrecoverableKeyException if the entry is a
       *          {@code PrivateKeyEntry} or {@code SecretKeyEntry}
       *          and the specified {@code protParam} 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, Entry, 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} under the specified alias.
       * The protection parameter is used to protect the
       * {@code Entry}.
       *
       * <p> If an entry already exists for the specified alias,
       * it is overridden.
       *
       * @param alias save the keystore {@code Entry} under this alias
       * @param entry the {@code Entry} to save
       * @param protParam the {@code ProtectionParameter}
       *          used to protect the {@code Entry},
       *          which may be {@code null}
       *
       * @exception NullPointerException if
       *          {@code alias} or {@code entry}
       *          is {@code null}
       * @exception KeyStoreException if the keystore has not been initialized
       *          (loaded), or if this operation fails for some other reason
       *
       * @see #getEntry(String, 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} for the specified
       * {@code alias} is an instance or subclass of the specified
       * {@code entryClass}.
       *
       * @param alias the alias name
       * @param entryClass the entry class
       *
       * @return true if the keystore {@code Entry} for the specified
       *          {@code alias} is an instance or subclass of the
       *          specified {@code entryClass}, false otherwise
       *
       * @exception NullPointerException if
       *          {@code alias} or {@code entryClass}
       *          is {@code null}
       * @exception KeyStoreException if the keystore has not been
       *          initialized (loaded)
       *
       * @since 1.5
       */
      public final boolean
          entryInstanceOf(String alias,
                          Class<? extends 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.
           *
           * @return the {@code KeyStore} described by this object
           * @exception KeyStoreException if an error occurred 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 Entry Entry} with the given alias.
           * The {@code getKeyStore} method must be invoked before this
           * method may be called.
           *
           * @return the ProtectionParameters that should be used to obtain
           *   the {@link 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 occurred 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}, the {@linkplain
           * #getProtectionParameter getProtectionParameter()} method will
           * return {@code protectionParameters}.
           *
           * <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} and call
           * its {@link KeyStore#load load()} method.
           * The {@code inputStream} argument is constructed from
           * {@code file}.
           * If {@code protection} is a
           * {@code PasswordProtection}, the password is obtained by
           * calling the {@code getPassword} method.
           * Otherwise, if {@code protection} is a
           * {@code CallbackHandlerProtection}, 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} if
           * non-null. Otherwise, all installed providers are searched.
           *
           * <p>Calls to {@link #getProtectionParameter getProtectionParameter()}
           * will return a {@link PasswordProtection PasswordProtection}
           * object encapsulating the password that was used to invoke the
           * {@code load} 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<KeyStore> action =
                          new PrivilegedExceptionAction<KeyStore>() {
                      public KeyStore 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 KeyStore 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 = 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}.
           * Its {@link KeyStore#load(LoadStoreParameter) load()}
           * method is invoked using a
           * {@code LoadStoreParameter} that encapsulates
           * {@code protection}.
           *
           * <p>The KeyStore is instantiated from {@code provider} if
           * non-null. Otherwise, all installed providers are searched.
           *
           * <p>Calls to {@link #getProtectionParameter getProtectionParameter()}
           * will return {@code protection}.
           *
           * <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<KeyStore> action
                          = new PrivilegedExceptionAction<KeyStore>() {
  
                      public KeyStore 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 AccessController.doPrivileged(action, context);
                      } 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;
          }
      }
  
  }
  