/*
    * Copyright 2014 The Netty Project
    *
    * The Netty Project licenses this file to you under the Apache License,
    * version 2.0 (the "License"); you may not use this file except in compliance
    * with the License. You may obtain a copy of the License at:
    *
    *   https://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations
   * under the License.
   */
  
  package io.netty.handler.ssl;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufAllocator;
  import io.netty.buffer.ByteBufInputStream;
  import io.netty.channel.ChannelInitializer;
  import io.netty.channel.ChannelPipeline;
  import io.netty.handler.ssl.ApplicationProtocolConfig.Protocol;
  import io.netty.handler.ssl.ApplicationProtocolConfig.SelectedListenerFailureBehavior;
  import io.netty.handler.ssl.ApplicationProtocolConfig.SelectorFailureBehavior;
  import io.netty.util.AttributeMap;
  import io.netty.util.DefaultAttributeMap;
  import io.netty.util.concurrent.ImmediateExecutor;
  import io.netty.util.internal.EmptyArrays;
  
  import java.io.BufferedInputStream;
  import java.io.File;
  import java.io.IOException;
  import java.io.InputStream;
  import java.security.AlgorithmParameters;
  import java.security.InvalidAlgorithmParameterException;
  import java.security.InvalidKeyException;
  import java.security.KeyException;
  import java.security.KeyFactory;
  import java.security.KeyStore;
  import java.security.KeyStoreException;
  import java.security.NoSuchAlgorithmException;
  import java.security.PrivateKey;
  import java.security.Provider;
  import java.security.SecureRandom;
  import java.security.UnrecoverableKeyException;
  import java.security.cert.CertificateException;
  import java.security.cert.CertificateFactory;
  import java.security.cert.X509Certificate;
  import java.security.spec.InvalidKeySpecException;
  import java.security.spec.PKCS8EncodedKeySpec;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.Executor;
  import javax.crypto.Cipher;
  import javax.crypto.EncryptedPrivateKeyInfo;
  import javax.crypto.NoSuchPaddingException;
  import javax.crypto.SecretKey;
  import javax.crypto.SecretKeyFactory;
  import javax.crypto.spec.PBEKeySpec;
  import javax.net.ssl.KeyManager;
  import javax.net.ssl.KeyManagerFactory;
  import javax.net.ssl.SSLContext;
  import javax.net.ssl.SSLEngine;
  import javax.net.ssl.SSLException;
  import javax.net.ssl.SSLSessionContext;
  import javax.net.ssl.TrustManager;
  import javax.net.ssl.TrustManagerFactory;
  
  /**
   * A secure socket protocol implementation which acts as a factory for {@link SSLEngine} and {@link SslHandler}.
   * Internally, it is implemented via JDK's {@link SSLContext} or OpenSSL's {@code SSL_CTX}.
   *
   * <h3>Making your server support SSL/TLS</h3>
   * <pre>
   * // In your {@link ChannelInitializer}:
   * {@link ChannelPipeline} p = channel.pipeline();
   * {@link SslContext} sslCtx = {@link SslContextBuilder#forServer(File, File) SslContextBuilder.forServer(...)}.build();
   * p.addLast("ssl", {@link #newHandler(ByteBufAllocator) sslCtx.newHandler(channel.alloc())});
   * ...
   * </pre>
   *
   * <h3>Making your client support SSL/TLS</h3>
   * <pre>
   * // In your {@link ChannelInitializer}:
   * {@link ChannelPipeline} p = channel.pipeline();
   * {@link SslContext} sslCtx = {@link SslContextBuilder#forClient() SslContextBuilder.forClient()}.build();
   * p.addLast("ssl", {@link #newHandler(ByteBufAllocator, String, int) sslCtx.newHandler(channel.alloc(), host, port)});
   * ...
   * </pre>
   */
  public abstract class SslContext {
      static final String ALIAS = "key";
  
      static final CertificateFactory X509_CERT_FACTORY;
      static {
          try {
              X509_CERT_FACTORY = CertificateFactory.getInstance("X.509");
         } catch (CertificateException e) {
             throw new IllegalStateException("unable to instance X.509 CertificateFactory", e);
         }
     }
 
     private final boolean startTls;
     private final AttributeMap attributes = new DefaultAttributeMap();
     final ResumptionController resumptionController;
     private static final String OID_PKCS5_PBES2 = "1.2.840.113549.1.5.13";
     private static final String PBES2 = "PBES2";
 
     /**
      * Returns the default server-side implementation provider currently in use.
      *
      * @return {@link SslProvider#OPENSSL} if OpenSSL is available. {@link SslProvider#JDK} otherwise.
      */
     public static SslProvider defaultServerProvider() {
         return defaultProvider();
     }
 
     /**
      * Returns the default client-side implementation provider currently in use.
      *
      * @return {@link SslProvider#OPENSSL} if OpenSSL is available. {@link SslProvider#JDK} otherwise.
      */
     public static SslProvider defaultClientProvider() {
         return defaultProvider();
     }
 
     private static SslProvider defaultProvider() {
         if (OpenSsl.isAvailable()) {
             return SslProvider.OPENSSL;
         } else {
             return SslProvider.JDK;
         }
     }
 
     /**
      * Creates a new server-side {@link SslContext}.
      *
      * @param certChainFile an X.509 certificate chain file in PEM format
      * @param keyFile a PKCS#8 private key file in PEM format
      * @return a new server-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newServerContext(File certChainFile, File keyFile) throws SSLException {
         return newServerContext(certChainFile, keyFile, null);
     }
 
     /**
      * Creates a new server-side {@link SslContext}.
      *
      * @param certChainFile an X.509 certificate chain file in PEM format
      * @param keyFile a PKCS#8 private key file in PEM format
      * @param keyPassword the password of the {@code keyFile}.
      *                    {@code null} if it's not password-protected.
      * @return a new server-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newServerContext(
             File certChainFile, File keyFile, String keyPassword) throws SSLException {
         return newServerContext(null, certChainFile, keyFile, keyPassword);
     }
 
     /**
      * Creates a new server-side {@link SslContext}.
      *
      * @param certChainFile an X.509 certificate chain file in PEM format
      * @param keyFile a PKCS#8 private key file in PEM format
      * @param keyPassword the password of the {@code keyFile}.
      *                    {@code null} if it's not password-protected.
      * @param ciphers the cipher suites to enable, in the order of preference.
      *                {@code null} to use the default cipher suites.
      * @param nextProtocols the application layer protocols to accept, in the order of preference.
      *                      {@code null} to disable TLS NPN/ALPN extension.
      * @param sessionCacheSize the size of the cache used for storing SSL session objects.
      *                         {@code 0} to use the default value.
      * @param sessionTimeout the timeout for the cached SSL session objects, in seconds.
      *                       {@code 0} to use the default value.
      * @return a new server-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newServerContext(
             File certChainFile, File keyFile, String keyPassword,
             Iterable<String> ciphers, Iterable<String> nextProtocols,
             long sessionCacheSize, long sessionTimeout) throws SSLException {
 
         return newServerContext(
                 null, certChainFile, keyFile, keyPassword,
                 ciphers, nextProtocols, sessionCacheSize, sessionTimeout);
     }
 
     /**
      * Creates a new server-side {@link SslContext}.
      *
      * @param certChainFile an X.509 certificate chain file in PEM format
      * @param keyFile a PKCS#8 private key file in PEM format
      * @param keyPassword the password of the {@code keyFile}.
      *                    {@code null} if it's not password-protected.
      * @param ciphers the cipher suites to enable, in the order of preference.
      *                {@code null} to use the default cipher suites.
      * @param cipherFilter a filter to apply over the supplied list of ciphers
      * @param apn Provides a means to configure parameters related to application protocol negotiation.
      * @param sessionCacheSize the size of the cache used for storing SSL session objects.
      *                         {@code 0} to use the default value.
      * @param sessionTimeout the timeout for the cached SSL session objects, in seconds.
      *                       {@code 0} to use the default value.
      * @return a new server-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newServerContext(
             File certChainFile, File keyFile, String keyPassword,
             Iterable<String> ciphers, CipherSuiteFilter cipherFilter, ApplicationProtocolConfig apn,
             long sessionCacheSize, long sessionTimeout) throws SSLException {
         return newServerContext(
                 null, certChainFile, keyFile, keyPassword,
                 ciphers, cipherFilter, apn, sessionCacheSize, sessionTimeout);
     }
 
     /**
      * Creates a new server-side {@link SslContext}.
      *
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param certChainFile an X.509 certificate chain file in PEM format
      * @param keyFile a PKCS#8 private key file in PEM format
      * @return a new server-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newServerContext(
             SslProvider provider, File certChainFile, File keyFile) throws SSLException {
         return newServerContext(provider, certChainFile, keyFile, null);
     }
 
     /**
      * Creates a new server-side {@link SslContext}.
      *
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param certChainFile an X.509 certificate chain file in PEM format
      * @param keyFile a PKCS#8 private key file in PEM format
      * @param keyPassword the password of the {@code keyFile}.
      *                    {@code null} if it's not password-protected.
      * @return a new server-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newServerContext(
             SslProvider provider, File certChainFile, File keyFile, String keyPassword) throws SSLException {
         return newServerContext(provider, certChainFile, keyFile, keyPassword, null, IdentityCipherSuiteFilter.INSTANCE,
                                 null, 0, 0);
     }
 
     /**
      * Creates a new server-side {@link SslContext}.
      *
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param certChainFile an X.509 certificate chain file in PEM format
      * @param keyFile a PKCS#8 private key file in PEM format
      * @param keyPassword the password of the {@code keyFile}.
      *                    {@code null} if it's not password-protected.
      * @param ciphers the cipher suites to enable, in the order of preference.
      *                {@code null} to use the default cipher suites.
      * @param nextProtocols the application layer protocols to accept, in the order of preference.
      *                      {@code null} to disable TLS NPN/ALPN extension.
      * @param sessionCacheSize the size of the cache used for storing SSL session objects.
      *                         {@code 0} to use the default value.
      * @param sessionTimeout the timeout for the cached SSL session objects, in seconds.
      *                       {@code 0} to use the default value.
      * @return a new server-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newServerContext(
             SslProvider provider,
             File certChainFile, File keyFile, String keyPassword,
             Iterable<String> ciphers, Iterable<String> nextProtocols,
             long sessionCacheSize, long sessionTimeout) throws SSLException {
         return newServerContext(provider, certChainFile, keyFile, keyPassword,
                                 ciphers, IdentityCipherSuiteFilter.INSTANCE,
                                 toApplicationProtocolConfig(nextProtocols), sessionCacheSize, sessionTimeout);
     }
 
     /**
      * Creates a new server-side {@link SslContext}.
      *
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param certChainFile an X.509 certificate chain file in PEM format
      * @param keyFile a PKCS#8 private key file in PEM format
      * @param keyPassword the password of the {@code keyFile}.
      *                    {@code null} if it's not password-protected.
      * @param trustManagerFactory the {@link TrustManagerFactory} that provides the {@link TrustManager}s
      *                            that verifies the certificates sent from servers.
      *                            {@code null} to use the default.
      * @param ciphers the cipher suites to enable, in the order of preference.
      *                {@code null} to use the default cipher suites.
      * @param nextProtocols the application layer protocols to accept, in the order of preference.
      *                      {@code null} to disable TLS NPN/ALPN extension.
      * @param sessionCacheSize the size of the cache used for storing SSL session objects.
      *                         {@code 0} to use the default value.
      * @param sessionTimeout the timeout for the cached SSL session objects, in seconds.
      *                       {@code 0} to use the default value.
      * @return a new server-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newServerContext(
             SslProvider provider,
             File certChainFile, File keyFile, String keyPassword, TrustManagerFactory trustManagerFactory,
             Iterable<String> ciphers, Iterable<String> nextProtocols,
             long sessionCacheSize, long sessionTimeout) throws SSLException {
 
         return newServerContext(
                 provider, null, trustManagerFactory, certChainFile, keyFile, keyPassword,
                 null, ciphers, IdentityCipherSuiteFilter.INSTANCE,
                 toApplicationProtocolConfig(nextProtocols), sessionCacheSize, sessionTimeout);
     }
 
     /**
      * Creates a new server-side {@link SslContext}.
      *
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param certChainFile an X.509 certificate chain file in PEM format
      * @param keyFile a PKCS#8 private key file in PEM format
      * @param keyPassword the password of the {@code keyFile}.
      *                    {@code null} if it's not password-protected.
      * @param ciphers the cipher suites to enable, in the order of preference.
      *                {@code null} to use the default cipher suites.
      * @param cipherFilter a filter to apply over the supplied list of ciphers
      *                Only required if {@code provider} is {@link SslProvider#JDK}
      * @param apn Provides a means to configure parameters related to application protocol negotiation.
      * @param sessionCacheSize the size of the cache used for storing SSL session objects.
      *                         {@code 0} to use the default value.
      * @param sessionTimeout the timeout for the cached SSL session objects, in seconds.
      *                       {@code 0} to use the default value.
      * @return a new server-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newServerContext(SslProvider provider,
             File certChainFile, File keyFile, String keyPassword,
             Iterable<String> ciphers, CipherSuiteFilter cipherFilter, ApplicationProtocolConfig apn,
             long sessionCacheSize, long sessionTimeout) throws SSLException {
         return newServerContext(provider, null, null, certChainFile, keyFile, keyPassword, null,
                 ciphers, cipherFilter, apn, sessionCacheSize, sessionTimeout, KeyStore.getDefaultType());
     }
 
     /**
      * Creates a new server-side {@link SslContext}.
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param trustCertCollectionFile an X.509 certificate collection file in PEM format.
      *                      This provides the certificate collection used for mutual authentication.
      *                      {@code null} to use the system default
      * @param trustManagerFactory the {@link TrustManagerFactory} that provides the {@link TrustManager}s
      *                            that verifies the certificates sent from clients.
      *                            {@code null} to use the default or the results of parsing
      *                            {@code trustCertCollectionFile}.
      *                            This parameter is ignored if {@code provider} is not {@link SslProvider#JDK}.
      * @param keyCertChainFile an X.509 certificate chain file in PEM format
      * @param keyFile a PKCS#8 private key file in PEM format
      * @param keyPassword the password of the {@code keyFile}.
      *                    {@code null} if it's not password-protected.
      * @param keyManagerFactory the {@link KeyManagerFactory} that provides the {@link KeyManager}s
      *                          that is used to encrypt data being sent to clients.
      *                          {@code null} to use the default or the results of parsing
      *                          {@code keyCertChainFile} and {@code keyFile}.
      *                          This parameter is ignored if {@code provider} is not {@link SslProvider#JDK}.
      * @param ciphers the cipher suites to enable, in the order of preference.
      *                {@code null} to use the default cipher suites.
      * @param cipherFilter a filter to apply over the supplied list of ciphers
      *                Only required if {@code provider} is {@link SslProvider#JDK}
      * @param apn Provides a means to configure parameters related to application protocol negotiation.
      * @param sessionCacheSize the size of the cache used for storing SSL session objects.
      *                         {@code 0} to use the default value.
      * @param sessionTimeout the timeout for the cached SSL session objects, in seconds.
      *                       {@code 0} to use the default value.
      * @return a new server-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newServerContext(
             SslProvider provider,
             File trustCertCollectionFile, TrustManagerFactory trustManagerFactory,
             File keyCertChainFile, File keyFile, String keyPassword, KeyManagerFactory keyManagerFactory,
             Iterable<String> ciphers, CipherSuiteFilter cipherFilter, ApplicationProtocolConfig apn,
             long sessionCacheSize, long sessionTimeout) throws SSLException {
         return newServerContext(provider, trustCertCollectionFile, trustManagerFactory, keyCertChainFile,
                 keyFile, keyPassword, keyManagerFactory, ciphers, cipherFilter, apn,
                 sessionCacheSize, sessionTimeout, KeyStore.getDefaultType());
     }
 
     /**
      * Creates a new server-side {@link SslContext}.
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param trustCertCollectionFile an X.509 certificate collection file in PEM format.
      *                      This provides the certificate collection used for mutual authentication.
      *                      {@code null} to use the system default
      * @param trustManagerFactory the {@link TrustManagerFactory} that provides the {@link TrustManager}s
      *                            that verifies the certificates sent from clients.
      *                            {@code null} to use the default or the results of parsing
      *                            {@code trustCertCollectionFile}.
      *                            This parameter is ignored if {@code provider} is not {@link SslProvider#JDK}.
      * @param keyCertChainFile an X.509 certificate chain file in PEM format
      * @param keyFile a PKCS#8 private key file in PEM format
      * @param keyPassword the password of the {@code keyFile}.
      *                    {@code null} if it's not password-protected.
      * @param keyManagerFactory the {@link KeyManagerFactory} that provides the {@link KeyManager}s
      *                          that is used to encrypt data being sent to clients.
      *                          {@code null} to use the default or the results of parsing
      *                          {@code keyCertChainFile} and {@code keyFile}.
      *                          This parameter is ignored if {@code provider} is not {@link SslProvider#JDK}.
      * @param ciphers the cipher suites to enable, in the order of preference.
      *                {@code null} to use the default cipher suites.
      * @param cipherFilter a filter to apply over the supplied list of ciphers
      *                Only required if {@code provider} is {@link SslProvider#JDK}
      * @param apn Provides a means to configure parameters related to application protocol negotiation.
      * @param sessionCacheSize the size of the cache used for storing SSL session objects.
      *                         {@code 0} to use the default value.
      * @param sessionTimeout the timeout for the cached SSL session objects, in seconds.
      *                       {@code 0} to use the default value.
      * @param keyStore the keystore type that should  be used
      * @return a new server-side {@link SslContext}
      */
     static SslContext newServerContext(
             SslProvider provider,
             File trustCertCollectionFile, TrustManagerFactory trustManagerFactory,
             File keyCertChainFile, File keyFile, String keyPassword, KeyManagerFactory keyManagerFactory,
             Iterable<String> ciphers, CipherSuiteFilter cipherFilter, ApplicationProtocolConfig apn,
             long sessionCacheSize, long sessionTimeout, String keyStore) throws SSLException {
         try {
             return newServerContextInternal(provider, null, toX509Certificates(trustCertCollectionFile),
                                             trustManagerFactory, toX509Certificates(keyCertChainFile),
                                             toPrivateKey(keyFile, keyPassword),
                                             keyPassword, keyManagerFactory, ciphers, cipherFilter, apn,
                                             sessionCacheSize, sessionTimeout, ClientAuth.NONE, null,
                                             false, false, null, keyStore);
         } catch (Exception e) {
             if (e instanceof SSLException) {
                 throw (SSLException) e;
             }
             throw new SSLException("failed to initialize the server-side SSL context", e);
         }
     }
 
     static SslContext newServerContextInternal(
             SslProvider provider,
             Provider sslContextProvider,
             X509Certificate[] trustCertCollection, TrustManagerFactory trustManagerFactory,
             X509Certificate[] keyCertChain, PrivateKey key, String keyPassword, KeyManagerFactory keyManagerFactory,
             Iterable<String> ciphers, CipherSuiteFilter cipherFilter, ApplicationProtocolConfig apn,
             long sessionCacheSize, long sessionTimeout, ClientAuth clientAuth, String[] protocols, boolean startTls,
             boolean enableOcsp, SecureRandom secureRandom, String keyStoreType,
             Map.Entry<SslContextOption<?>, Object>... ctxOptions)
             throws SSLException {
 
         if (provider == null) {
             provider = defaultServerProvider();
         }
 
         ResumptionController resumptionController = new ResumptionController();
 
         switch (provider) {
         case JDK:
             if (enableOcsp) {
                 throw new IllegalArgumentException("OCSP is not supported with this SslProvider: " + provider);
             }
             return new JdkSslServerContext(sslContextProvider,
                     trustCertCollection, trustManagerFactory, keyCertChain, key, keyPassword,
                     keyManagerFactory, ciphers, cipherFilter, apn, sessionCacheSize, sessionTimeout,
                     clientAuth, protocols, startTls, secureRandom, keyStoreType, resumptionController);
         case OPENSSL:
             verifyNullSslContextProvider(provider, sslContextProvider);
             return new OpenSslServerContext(
                     trustCertCollection, trustManagerFactory, keyCertChain, key, keyPassword,
                     keyManagerFactory, ciphers, cipherFilter, apn, sessionCacheSize, sessionTimeout,
                     clientAuth, protocols, startTls, enableOcsp, keyStoreType, resumptionController, ctxOptions);
         case OPENSSL_REFCNT:
             verifyNullSslContextProvider(provider, sslContextProvider);
             return new ReferenceCountedOpenSslServerContext(
                     trustCertCollection, trustManagerFactory, keyCertChain, key, keyPassword,
                     keyManagerFactory, ciphers, cipherFilter, apn, sessionCacheSize, sessionTimeout,
                     clientAuth, protocols, startTls, enableOcsp, keyStoreType, resumptionController, ctxOptions);
         default:
             throw new Error(provider.toString());
         }
     }
 
     private static void verifyNullSslContextProvider(SslProvider provider, Provider sslContextProvider) {
         if (sslContextProvider != null) {
             throw new IllegalArgumentException("Java Security Provider unsupported for SslProvider: " + provider);
         }
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext() throws SSLException {
         return newClientContext(null, null, null);
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      *
      * @param certChainFile an X.509 certificate chain file in PEM format
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext(File certChainFile) throws SSLException {
         return newClientContext(null, certChainFile);
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      *
      * @param trustManagerFactory the {@link TrustManagerFactory} that provides the {@link TrustManager}s
      *                            that verifies the certificates sent from servers.
      *                            {@code null} to use the default.
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext(TrustManagerFactory trustManagerFactory) throws SSLException {
         return newClientContext(null, null, trustManagerFactory);
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      *
      * @param certChainFile an X.509 certificate chain file in PEM format.
      *                      {@code null} to use the system default
      * @param trustManagerFactory the {@link TrustManagerFactory} that provides the {@link TrustManager}s
      *                            that verifies the certificates sent from servers.
      *                            {@code null} to use the default.
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext(
             File certChainFile, TrustManagerFactory trustManagerFactory) throws SSLException {
         return newClientContext(null, certChainFile, trustManagerFactory);
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      *
      * @param certChainFile an X.509 certificate chain file in PEM format.
      *                      {@code null} to use the system default
      * @param trustManagerFactory the {@link TrustManagerFactory} that provides the {@link TrustManager}s
      *                            that verifies the certificates sent from servers.
      *                            {@code null} to use the default.
      * @param ciphers the cipher suites to enable, in the order of preference.
      *                {@code null} to use the default cipher suites.
      * @param nextProtocols the application layer protocols to accept, in the order of preference.
      *                      {@code null} to disable TLS NPN/ALPN extension.
      * @param sessionCacheSize the size of the cache used for storing SSL session objects.
      *                         {@code 0} to use the default value.
      * @param sessionTimeout the timeout for the cached SSL session objects, in seconds.
      *                       {@code 0} to use the default value.
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext(
             File certChainFile, TrustManagerFactory trustManagerFactory,
             Iterable<String> ciphers, Iterable<String> nextProtocols,
             long sessionCacheSize, long sessionTimeout) throws SSLException {
         return newClientContext(
                 null, certChainFile, trustManagerFactory,
                 ciphers, nextProtocols, sessionCacheSize, sessionTimeout);
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      *
      * @param certChainFile an X.509 certificate chain file in PEM format.
      *                      {@code null} to use the system default
      * @param trustManagerFactory the {@link TrustManagerFactory} that provides the {@link TrustManager}s
      *                            that verifies the certificates sent from servers.
      *                            {@code null} to use the default.
      * @param ciphers the cipher suites to enable, in the order of preference.
      *                {@code null} to use the default cipher suites.
      * @param cipherFilter a filter to apply over the supplied list of ciphers
      * @param apn Provides a means to configure parameters related to application protocol negotiation.
      * @param sessionCacheSize the size of the cache used for storing SSL session objects.
      *                         {@code 0} to use the default value.
      * @param sessionTimeout the timeout for the cached SSL session objects, in seconds.
      *                       {@code 0} to use the default value.
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext(
             File certChainFile, TrustManagerFactory trustManagerFactory,
             Iterable<String> ciphers, CipherSuiteFilter cipherFilter, ApplicationProtocolConfig apn,
             long sessionCacheSize, long sessionTimeout) throws SSLException {
         return newClientContext(
                 null, certChainFile, trustManagerFactory,
                 ciphers, cipherFilter, apn, sessionCacheSize, sessionTimeout);
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      *
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext(SslProvider provider) throws SSLException {
         return newClientContext(provider, null, null);
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      *
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param certChainFile an X.509 certificate chain file in PEM format.
      *                      {@code null} to use the system default
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext(SslProvider provider, File certChainFile) throws SSLException {
         return newClientContext(provider, certChainFile, null);
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      *
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param trustManagerFactory the {@link TrustManagerFactory} that provides the {@link TrustManager}s
      *                            that verifies the certificates sent from servers.
      *                            {@code null} to use the default.
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext(
             SslProvider provider, TrustManagerFactory trustManagerFactory) throws SSLException {
         return newClientContext(provider, null, trustManagerFactory);
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      *
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param certChainFile an X.509 certificate chain file in PEM format.
      *                      {@code null} to use the system default
      * @param trustManagerFactory the {@link TrustManagerFactory} that provides the {@link TrustManager}s
      *                            that verifies the certificates sent from servers.
      *                            {@code null} to use the default.
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext(
             SslProvider provider, File certChainFile, TrustManagerFactory trustManagerFactory) throws SSLException {
         return newClientContext(provider, certChainFile, trustManagerFactory, null, IdentityCipherSuiteFilter.INSTANCE,
                 null, 0, 0);
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      *
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param certChainFile an X.509 certificate chain file in PEM format.
      *                      {@code null} to use the system default
      * @param trustManagerFactory the {@link TrustManagerFactory} that provides the {@link TrustManager}s
      *                            that verifies the certificates sent from servers.
      *                            {@code null} to use the default.
      * @param ciphers the cipher suites to enable, in the order of preference.
      *                {@code null} to use the default cipher suites.
      * @param nextProtocols the application layer protocols to accept, in the order of preference.
      *                      {@code null} to disable TLS NPN/ALPN extension.
      * @param sessionCacheSize the size of the cache used for storing SSL session objects.
      *                         {@code 0} to use the default value.
      * @param sessionTimeout the timeout for the cached SSL session objects, in seconds.
      *                       {@code 0} to use the default value.
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext(
             SslProvider provider,
             File certChainFile, TrustManagerFactory trustManagerFactory,
             Iterable<String> ciphers, Iterable<String> nextProtocols,
             long sessionCacheSize, long sessionTimeout) throws SSLException {
         return newClientContext(
                 provider, certChainFile, trustManagerFactory, null, null, null, null,
                 ciphers, IdentityCipherSuiteFilter.INSTANCE,
                 toApplicationProtocolConfig(nextProtocols), sessionCacheSize, sessionTimeout);
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      *
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param certChainFile an X.509 certificate chain file in PEM format.
      *                      {@code null} to use the system default
      * @param trustManagerFactory the {@link TrustManagerFactory} that provides the {@link TrustManager}s
      *                            that verifies the certificates sent from servers.
      *                            {@code null} to use the default.
      * @param ciphers the cipher suites to enable, in the order of preference.
      *                {@code null} to use the default cipher suites.
      * @param cipherFilter a filter to apply over the supplied list of ciphers
      * @param apn Provides a means to configure parameters related to application protocol negotiation.
      * @param sessionCacheSize the size of the cache used for storing SSL session objects.
      *                         {@code 0} to use the default value.
      * @param sessionTimeout the timeout for the cached SSL session objects, in seconds.
      *                       {@code 0} to use the default value.
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext(
             SslProvider provider,
             File certChainFile, TrustManagerFactory trustManagerFactory,
             Iterable<String> ciphers, CipherSuiteFilter cipherFilter, ApplicationProtocolConfig apn,
             long sessionCacheSize, long sessionTimeout) throws SSLException {
 
         return newClientContext(
                 provider, certChainFile, trustManagerFactory, null, null, null, null,
                 ciphers, cipherFilter, apn, sessionCacheSize, sessionTimeout);
     }
 
     /**
      * Creates a new client-side {@link SslContext}.
      * @param provider the {@link SslContext} implementation to use.
      *                 {@code null} to use the current default one.
      * @param trustCertCollectionFile an X.509 certificate collection file in PEM format.
      *                      {@code null} to use the system default
      * @param trustManagerFactory the {@link TrustManagerFactory} that provides the {@link TrustManager}s
      *                            that verifies the certificates sent from servers.
      *                            {@code null} to use the default or the results of parsing
      *                            {@code trustCertCollectionFile}.
      *                            This parameter is ignored if {@code provider} is not {@link SslProvider#JDK}.
      * @param keyCertChainFile an X.509 certificate chain file in PEM format.
      *                      This provides the public key for mutual authentication.
      *                      {@code null} to use the system default
      * @param keyFile a PKCS#8 private key file in PEM format.
      *                      This provides the private key for mutual authentication.
      *                      {@code null} for no mutual authentication.
      * @param keyPassword the password of the {@code keyFile}.
      *                    {@code null} if it's not password-protected.
      *                    Ignored if {@code keyFile} is {@code null}.
      * @param keyManagerFactory the {@link KeyManagerFactory} that provides the {@link KeyManager}s
      *                          that is used to encrypt data being sent to servers.
      *                          {@code null} to use the default or the results of parsing
      *                          {@code keyCertChainFile} and {@code keyFile}.
      *                          This parameter is ignored if {@code provider} is not {@link SslProvider#JDK}.
      * @param ciphers the cipher suites to enable, in the order of preference.
      *                {@code null} to use the default cipher suites.
      * @param cipherFilter a filter to apply over the supplied list of ciphers
      * @param apn Provides a means to configure parameters related to application protocol negotiation.
      * @param sessionCacheSize the size of the cache used for storing SSL session objects.
      *                         {@code 0} to use the default value.
      * @param sessionTimeout the timeout for the cached SSL session objects, in seconds.
      *                       {@code 0} to use the default value.
      *
      * @return a new client-side {@link SslContext}
      * @deprecated Replaced by {@link SslContextBuilder}
      */
     @Deprecated
     public static SslContext newClientContext(
         SslProvider provider,
         File trustCertCollectionFile, TrustManagerFactory trustManagerFactory,
         File keyCertChainFile, File keyFile, String keyPassword,
         KeyManagerFactory keyManagerFactory,
         Iterable<String> ciphers, CipherSuiteFilter cipherFilter, ApplicationProtocolConfig apn,
         long sessionCacheSize, long sessionTimeout) throws SSLException {
         try {
             return newClientContextInternal(provider, null,
                                             toX509Certificates(trustCertCollectionFile), trustManagerFactory,
                                             toX509Certificates(keyCertChainFile), toPrivateKey(keyFile, keyPassword),
                                             keyPassword, keyManagerFactory, ciphers, cipherFilter,
                                             apn, null, sessionCacheSize, sessionTimeout, false,
                                             null, KeyStore.getDefaultType(), "HTTPS");
         } catch (Exception e) {
             if (e instanceof SSLException) {
                 throw (SSLException) e;
             }
             throw new SSLException("failed to initialize the client-side SSL context", e);
         }
     }
 
     static SslContext newClientContextInternal(
             SslProvider provider,
             Provider sslContextProvider,
             X509Certificate[] trustCert, TrustManagerFactory trustManagerFactory,
             X509Certificate[] keyCertChain, PrivateKey key, String keyPassword, KeyManagerFactory keyManagerFactory,
             Iterable<String> ciphers, CipherSuiteFilter cipherFilter, ApplicationProtocolConfig apn, String[] protocols,
             long sessionCacheSize, long sessionTimeout, boolean enableOcsp,
             SecureRandom secureRandom, String keyStoreType, String endpointIdentificationAlgorithm,
             Map.Entry<SslContextOption<?>, Object>... options) throws SSLException {
         if (provider == null) {
             provider = defaultClientProvider();
         }
 
         ResumptionController resumptionController = new ResumptionController();
 
         switch (provider) {
             case JDK:
                 if (enableOcsp) {
                     throw new IllegalArgumentException("OCSP is not supported with this SslProvider: " + provider);
                 }
                 return new JdkSslClientContext(sslContextProvider,
                         trustCert, trustManagerFactory, keyCertChain, key, keyPassword,
                         keyManagerFactory, ciphers, cipherFilter, apn, protocols, sessionCacheSize,
                         sessionTimeout, secureRandom, keyStoreType, endpointIdentificationAlgorithm,
                         resumptionController);
             case OPENSSL:
                 verifyNullSslContextProvider(provider, sslContextProvider);
                 OpenSsl.ensureAvailability();
                 return new OpenSslClientContext(
                         trustCert, trustManagerFactory, keyCertChain, key, keyPassword,
                         keyManagerFactory, ciphers, cipherFilter, apn, protocols, sessionCacheSize, sessionTimeout,
                         enableOcsp, keyStoreType, endpointIdentificationAlgorithm, resumptionController, options);
             case OPENSSL_REFCNT:
                 verifyNullSslContextProvider(provider, sslContextProvider);
                 OpenSsl.ensureAvailability();
                 return new ReferenceCountedOpenSslClientContext(
                         trustCert, trustManagerFactory, keyCertChain, key, keyPassword,
                         keyManagerFactory, ciphers, cipherFilter, apn, protocols, sessionCacheSize, sessionTimeout,
                         enableOcsp, keyStoreType, endpointIdentificationAlgorithm, resumptionController, options);
             default:
                 throw new Error(provider.toString());
         }
     }
 
     static ApplicationProtocolConfig toApplicationProtocolConfig(Iterable<String> nextProtocols) {
         ApplicationProtocolConfig apn;
         if (nextProtocols == null) {
             apn = ApplicationProtocolConfig.DISABLED;
         } else {
             apn = new ApplicationProtocolConfig(
                     Protocol.NPN_AND_ALPN, SelectorFailureBehavior.CHOOSE_MY_LAST_PROTOCOL,
                     SelectedListenerFailureBehavior.ACCEPT, nextProtocols);
         }
         return apn;
     }
 
     /**
      * Creates a new instance (startTls set to {@code false}).
      */
     protected SslContext() {
         this(false);
     }
 
     /**
      * Creates a new instance.
      */
     protected SslContext(boolean startTls) {
         this(startTls, null);
     }
 
     SslContext(boolean startTls, ResumptionController resumptionController) {
         this.startTls = startTls;
         this.resumptionController = resumptionController;
     }
 
     /**
      * Returns the {@link AttributeMap} that belongs to this {@link SslContext} .
      */
     public final AttributeMap attributes() {
         return attributes;
     }
 
     /**
      * Returns {@code true} if and only if this context is for server-side.
      */
     public final boolean isServer() {
         return !isClient();
     }
 
     /**
      * Returns the {@code true} if and only if this context is for client-side.
      */
     public abstract boolean isClient();
 
     /**
      * Returns the list of enabled cipher suites, in the order of preference.
      */
     public abstract List<String> cipherSuites();
 
     /**
      * Returns the size of the cache used for storing SSL session objects.
      */
     public long sessionCacheSize() {
         return sessionContext().getSessionCacheSize();
     }
 
     /**
      * Returns the timeout for the cached SSL session objects, in seconds.
      */
     public long sessionTimeout() {
         return sessionContext().getSessionTimeout();
     }
 
     /**
      * @deprecated Use {@link #applicationProtocolNegotiator()} instead.
      */
     @Deprecated
     public final List<String> nextProtocols() {
         return applicationProtocolNegotiator().protocols();
     }
 
     /**
      * Returns the object responsible for negotiating application layer protocols for the TLS NPN/ALPN extensions.
      */
     public abstract ApplicationProtocolNegotiator applicationProtocolNegotiator();
 
     /**
      * Creates a new {@link SSLEngine}.
      * <p>If {@link SslProvider#OPENSSL_REFCNT} is used then the object must be released. One way to do this is to
      * wrap in a {@link SslHandler} and insert it into a pipeline. See {@link #newHandler(ByteBufAllocator)}.
      * @return a new {@link SSLEngine}
      */
     public abstract SSLEngine newEngine(ByteBufAllocator alloc);
 
     /**
      * Creates a new {@link SSLEngine} using advisory peer information.
      * <p>If {@link SslProvider#OPENSSL_REFCNT} is used then the object must be released. One way to do this is to
      * wrap in a {@link SslHandler} and insert it into a pipeline.
      * See {@link #newHandler(ByteBufAllocator, String, int)}.
      * @param peerHost the non-authoritative name of the host
      * @param peerPort the non-authoritative port
      *
      * @return a new {@link SSLEngine}
      */
     public abstract SSLEngine newEngine(ByteBufAllocator alloc, String peerHost, int peerPort);
 
     /**
      * Returns the {@link SSLSessionContext} object held by this context.
      */
     public abstract SSLSessionContext sessionContext();
 
     /**
      * Create a new SslHandler.
      * @see #newHandler(ByteBufAllocator, Executor)
      */
     public final SslHandler newHandler(ByteBufAllocator alloc) {
         return newHandler(alloc, startTls);
     }
 
     /**
      * Create a new SslHandler.
      * @see #newHandler(ByteBufAllocator)
      */
     protected SslHandler newHandler(ByteBufAllocator alloc, boolean startTls) {
         return new SslHandler(newEngine(alloc), startTls, ImmediateExecutor.INSTANCE, resumptionController);
     }
 
     /**
      * Creates a new {@link SslHandler}.
      * <p>If {@link SslProvider#OPENSSL_REFCNT} is used then the returned {@link SslHandler} will release the engine
      * that is wrapped. If the returned {@link SslHandler} is not inserted into a pipeline then you may leak native
      * memory!
      * <p><b>Beware</b>: the underlying generated {@link SSLEngine} won't have
      * <a href="https://wiki.openssl.org/index.php/Hostname_validation">hostname verification</a> enabled by default.
      * If you create {@link SslHandler} for the client side and want proper security, we advice that you configure
      * the {@link SSLEngine} (see {@link javax.net.ssl.SSLParameters#setEndpointIdentificationAlgorithm(String)}):
      * <pre>
      * SSLEngine sslEngine = sslHandler.engine();
      * SSLParameters sslParameters = sslEngine.getSSLParameters();
      * // only available since Java 7
      * sslParameters.setEndpointIdentificationAlgorithm("HTTPS");
      * sslEngine.setSSLParameters(sslParameters);
      * </pre>
      * <p>
      * The underlying {@link SSLEngine} may not follow the restrictions imposed by the
      * <a href="https://docs.oracle.com/javase/7/docs/api/javax/net/ssl/SSLEngine.html">SSLEngine javadocs</a> which
      * limits wrap/unwrap to operate on a single SSL/TLS packet.
      * @param alloc If supported by the SSLEngine then the SSLEngine will use this to allocate ByteBuf objects.
      * @param delegatedTaskExecutor the {@link Executor} that will be used to execute tasks that are returned by
      *                              {@link SSLEngine#getDelegatedTask()}.
      * @return a new {@link SslHandler}
      */
     public SslHandler newHandler(ByteBufAllocator alloc, Executor delegatedTaskExecutor) {
         return newHandler(alloc, startTls, delegatedTaskExecutor);
     }
 
     /**
      * Create a new SslHandler.
      * @see #newHandler(ByteBufAllocator, String, int, boolean, Executor)
      */
     protected SslHandler newHandler(ByteBufAllocator alloc, boolean startTls, Executor executor) {
         return new SslHandler(newEngine(alloc), startTls, executor, resumptionController);
     }
 
     /**
      * Creates a new {@link SslHandler}
      *
      * @see #newHandler(ByteBufAllocator, String, int, Executor)
      */
     public final SslHandler newHandler(ByteBufAllocator alloc, String peerHost, int peerPort) {
         return newHandler(alloc, peerHost, peerPort, startTls);
     }
 
     /**
      * Create a new SslHandler.
      * @see #newHandler(ByteBufAllocator, String, int, boolean, Executor)
      */
     protected SslHandler newHandler(ByteBufAllocator alloc, String peerHost, int peerPort, boolean startTls) {
         return new SslHandler(newEngine(alloc, peerHost, peerPort), startTls, ImmediateExecutor.INSTANCE,
                 resumptionController);
     }
 
     /**
      * Creates a new {@link SslHandler} with advisory peer information.
      * <p>If {@link SslProvider#OPENSSL_REFCNT} is used then the returned {@link SslHandler} will release the engine
      * that is wrapped. If the returned {@link SslHandler} is not inserted into a pipeline then you may leak native
      * memory!
      * <p><b>Beware</b>: the underlying generated {@link SSLEngine} won't have
      * <a href="https://wiki.openssl.org/index.php/Hostname_validation">hostname verification</a> enabled by default.
      * If you create {@link SslHandler} for the client side and want proper security, we advice that you configure
      * the {@link SSLEngine} (see {@link javax.net.ssl.SSLParameters#setEndpointIdentificationAlgorithm(String)}):
      * <pre>
      * SSLEngine sslEngine = sslHandler.engine();
      * SSLParameters sslParameters = sslEngine.getSSLParameters();
      * // only available since Java 7
      * sslParameters.setEndpointIdentificationAlgorithm("HTTPS");
      * sslEngine.setSSLParameters(sslParameters);
      * </pre>
      * <p>
      * The underlying {@link SSLEngine} may not follow the restrictions imposed by the
      * <a href="https://docs.oracle.com/javase/7/docs/api/javax/net/ssl/SSLEngine.html">SSLEngine javadocs</a> which
      * limits wrap/unwrap to operate on a single SSL/TLS packet.
      * @param alloc If supported by the SSLEngine then the SSLEngine will use this to allocate ByteBuf objects.
      * @param peerHost the non-authoritative name of the host
      * @param peerPort the non-authoritative port
      * @param delegatedTaskExecutor the {@link Executor} that will be used to execute tasks that are returned by
      *                              {@link SSLEngine#getDelegatedTask()}.
      *
      * @return a new {@link SslHandler}
      */
     public SslHandler newHandler(ByteBufAllocator alloc, String peerHost, int peerPort,
                                  Executor delegatedTaskExecutor) {
         return newHandler(alloc, peerHost, peerPort, startTls, delegatedTaskExecutor);
     }
 
     protected SslHandler newHandler(ByteBufAllocator alloc, String peerHost, int peerPort, boolean startTls,
                                     Executor delegatedTaskExecutor) {
         return new SslHandler(newEngine(alloc, peerHost, peerPort), startTls, delegatedTaskExecutor,
                 resumptionController);
     }
 
     /**
      * Generates a key specification for an (encrypted) private key.
      *
      * @param password characters, if {@code null} an unencrypted key is assumed
      * @param key bytes of the DER encoded private key
      *
      * @return a key specification
      *
      * @throws IOException if parsing {@code key} fails
      * @throws NoSuchAlgorithmException if the algorithm used to encrypt {@code key} is unknown
      * @throws NoSuchPaddingException if the padding scheme specified in the decryption algorithm is unknown
      * @throws InvalidKeySpecException if the decryption key based on {@code password} cannot be generated
      * @throws InvalidKeyException if the decryption key based on {@code password} cannot be used to decrypt
      *                             {@code key}
      * @throws InvalidAlgorithmParameterException if decryption algorithm parameters are somehow faulty
      */
     @Deprecated
     protected static PKCS8EncodedKeySpec generateKeySpec(char[] password, byte[] key)
             throws IOException, NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeySpecException,
             InvalidKeyException, InvalidAlgorithmParameterException {
 
         if (password == null) {
             return new PKCS8EncodedKeySpec(key);
         }
 
         EncryptedPrivateKeyInfo encryptedPrivateKeyInfo = new EncryptedPrivateKeyInfo(key);
         String pbeAlgorithm = getPBEAlgorithm(encryptedPrivateKeyInfo);
         SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(pbeAlgorithm);
         PBEKeySpec pbeKeySpec = new PBEKeySpec(password);
         SecretKey pbeKey = keyFactory.generateSecret(pbeKeySpec);
 
         Cipher cipher = Cipher.getInstance(pbeAlgorithm);
         cipher.init(Cipher.DECRYPT_MODE, pbeKey, encryptedPrivateKeyInfo.getAlgParameters());
 
         return encryptedPrivateKeyInfo.getKeySpec(cipher);
     }
 
     private static String getPBEAlgorithm(EncryptedPrivateKeyInfo encryptedPrivateKeyInfo) {
         AlgorithmParameters parameters = encryptedPrivateKeyInfo.getAlgParameters();
         String algName = encryptedPrivateKeyInfo.getAlgName();
         // Java 8 ~ 16 returns OID_PKCS5_PBES2
         // Java 17+ returns PBES2
         if (parameters != null && (OID_PKCS5_PBES2.equals(algName) || PBES2.equals(algName))) {
             /*
              * This should be "PBEWith<prf>And<encryption>".
              * Relying on the toString() implementation is potentially
              * fragile but acceptable in this case since the JRE depends on
              * the toString() implementation as well.
              * In the future, if necessary, we can parse the value of
              * parameters.getEncoded() but the associated complexity and
              * unlikeliness of the JRE implementation changing means that
              * Tomcat will use to toString() approach for now.
              */
             return parameters.toString();
         }
         return encryptedPrivateKeyInfo.getAlgName();
     }
 
     /**
      * Generates a new {@link KeyStore}.
      *
      * @param certChain an X.509 certificate chain
      * @param key a PKCS#8 private key
      * @param keyPasswordChars the password of the {@code keyFile}.
      *                    {@code null} if it's not password-protected.
      * @param keyStoreType The KeyStore Type you want to use
      * @return generated {@link KeyStore}.
      */
     protected static KeyStore buildKeyStore(X509Certificate[] certChain, PrivateKey key,
                                   char[] keyPasswordChars, String keyStoreType)
             throws KeyStoreException, NoSuchAlgorithmException,
                    CertificateException, IOException {
         if (keyStoreType == null) {
             keyStoreType = KeyStore.getDefaultType();
         }
         KeyStore ks = KeyStore.getInstance(keyStoreType);
         ks.load(null, null);
         ks.setKeyEntry(ALIAS, key, keyPasswordChars, certChain);
         return ks;
     }
 
     protected static PrivateKey toPrivateKey(File keyFile, String keyPassword) throws NoSuchAlgorithmException,
                                                                 NoSuchPaddingException, InvalidKeySpecException,
                                                                 InvalidAlgorithmParameterException,
                                                                 KeyException, IOException {
         return toPrivateKey(keyFile, keyPassword, true);
     }
 
     static PrivateKey toPrivateKey(File keyFile, String keyPassword, boolean tryBouncyCastle)
             throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeySpecException,
             InvalidAlgorithmParameterException,
             KeyException, IOException {
         if (keyFile == null) {
             return null;
         }
 
         // try BC first, if this fail fallback to original key extraction process
         if (tryBouncyCastle && BouncyCastlePemReader.isAvailable()) {
             PrivateKey pk = BouncyCastlePemReader.getPrivateKey(keyFile, keyPassword);
             if (pk != null) {
                 return pk;
             }
         }
 
         return getPrivateKeyFromByteBuffer(PemReader.readPrivateKey(keyFile), keyPassword);
     }
 
     protected static PrivateKey toPrivateKey(InputStream keyInputStream, String keyPassword)
                                                                 throws NoSuchAlgorithmException,
                                                                 NoSuchPaddingException, InvalidKeySpecException,
                                                                 InvalidAlgorithmParameterException,
                                                                 KeyException, IOException {
         if (keyInputStream == null) {
             return null;
         }
 
         // try BC first, if this fail fallback to original key extraction process
         if (BouncyCastlePemReader.isAvailable()) {
             if (!keyInputStream.markSupported()) {
                 // We need an input stream that supports resetting, in case BouncyCastle fails to read.
                 keyInputStream = new BufferedInputStream(keyInputStream);
             }
             keyInputStream.mark(1048576); // Be able to reset up to 1 MiB of data.
             PrivateKey pk = BouncyCastlePemReader.getPrivateKey(keyInputStream, keyPassword);
             if (pk != null) {
                 return pk;
             }
             // BouncyCastle could not read the key. Reset the input stream in case the input position changed.
             keyInputStream.reset();
         }
 
         return getPrivateKeyFromByteBuffer(PemReader.readPrivateKey(keyInputStream), keyPassword);
     }
 
     private static PrivateKey getPrivateKeyFromByteBuffer(ByteBuf encodedKeyBuf, String keyPassword)
             throws NoSuchAlgorithmException, NoSuchPaddingException, InvalidKeySpecException,
             InvalidAlgorithmParameterException, KeyException, IOException {
 
         byte[] encodedKey = new byte[encodedKeyBuf.readableBytes()];
         encodedKeyBuf.readBytes(encodedKey).release();
 
         PKCS8EncodedKeySpec encodedKeySpec = generateKeySpec(
                 keyPassword == null ? null : keyPassword.toCharArray(), encodedKey);
         try {
             return KeyFactory.getInstance("RSA").generatePrivate(encodedKeySpec);
         } catch (InvalidKeySpecException ignore) {
             try {
                 return KeyFactory.getInstance("DSA").generatePrivate(encodedKeySpec);
             } catch (InvalidKeySpecException ignore2) {
                 try {
                     return KeyFactory.getInstance("EC").generatePrivate(encodedKeySpec);
                 } catch (InvalidKeySpecException e) {
                     throw new InvalidKeySpecException("Neither RSA, DSA nor EC worked", e);
                 }
             }
         }
     }
 
     /**
      * Build a {@link TrustManagerFactory} from a certificate chain file.
      * @param certChainFile The certificate file to build from.
      * @param trustManagerFactory The existing {@link TrustManagerFactory} that will be used if not {@code null}.
      * @return A {@link TrustManagerFactory} which contains the certificates in {@code certChainFile}
      */
     @Deprecated
     protected static TrustManagerFactory buildTrustManagerFactory(
             File certChainFile, TrustManagerFactory trustManagerFactory)
             throws NoSuchAlgorithmException, CertificateException, KeyStoreException, IOException {
         return buildTrustManagerFactory(certChainFile, trustManagerFactory, null);
     }
 
     /**
      * Build a {@link TrustManagerFactory} from a certificate chain file.
      * @param certChainFile The certificate file to build from.
      * @param trustManagerFactory The existing {@link TrustManagerFactory} that will be used if not {@code null}.
      * @param keyType The KeyStore Type you want to use
      * @return A {@link TrustManagerFactory} which contains the certificates in {@code certChainFile}
      */
     protected static TrustManagerFactory buildTrustManagerFactory(
             File certChainFile, TrustManagerFactory trustManagerFactory, String keyType)
             throws NoSuchAlgorithmException, CertificateException, KeyStoreException, IOException {
         X509Certificate[] x509Certs = toX509Certificates(certChainFile);
 
         return buildTrustManagerFactory(x509Certs, trustManagerFactory, keyType);
     }
 
     protected static X509Certificate[] toX509Certificates(File file) throws CertificateException {
         if (file == null) {
             return null;
         }
         return getCertificatesFromBuffers(PemReader.readCertificates(file));
     }
 
     protected static X509Certificate[] toX509Certificates(InputStream in) throws CertificateException {
         if (in == null) {
             return null;
         }
         return getCertificatesFromBuffers(PemReader.readCertificates(in));
     }
 
     private static X509Certificate[] getCertificatesFromBuffers(ByteBuf[] certs) throws CertificateException {
         CertificateFactory cf = CertificateFactory.getInstance("X.509");
         X509Certificate[] x509Certs = new X509Certificate[certs.length];
 
         try {
             for (int i = 0; i < certs.length; i++) {
                 InputStream is = new ByteBufInputStream(certs[i], false);
                 try {
                     x509Certs[i] = (X509Certificate) cf.generateCertificate(is);
                 } finally {
                     try {
                         is.close();
                     } catch (IOException e) {
                         // This is not expected to happen, but re-throw in case it does.
                         throw new RuntimeException(e);
                     }
                 }
             }
         } finally {
             for (ByteBuf buf: certs) {
                 buf.release();
             }
         }
         return x509Certs;
     }
 
     protected static TrustManagerFactory buildTrustManagerFactory(
             X509Certificate[] certCollection, TrustManagerFactory trustManagerFactory, String keyStoreType)
             throws NoSuchAlgorithmException, CertificateException, KeyStoreException, IOException {
         if (keyStoreType == null) {
             keyStoreType = KeyStore.getDefaultType();
         }
         final KeyStore ks = KeyStore.getInstance(keyStoreType);
         ks.load(null, null);
 
         int i = 1;
         for (X509Certificate cert: certCollection) {
             String alias = Integer.toString(i);
             ks.setCertificateEntry(alias, cert);
             i++;
         }
 
         // Set up trust manager factory to use our key store.
         if (trustManagerFactory == null) {
             trustManagerFactory = TrustManagerFactory.getInstance(TrustManagerFactory.getDefaultAlgorithm());
         }
         trustManagerFactory.init(ks);
 
         return trustManagerFactory;
     }
 
     static PrivateKey toPrivateKeyInternal(File keyFile, String keyPassword) throws SSLException {
         try {
             return toPrivateKey(keyFile, keyPassword);
         } catch (Exception e) {
             throw new SSLException(e);
         }
     }
 
     static X509Certificate[] toX509CertificatesInternal(File file) throws SSLException {
         try {
             return toX509Certificates(file);
         } catch (CertificateException e) {
             throw new SSLException(e);
         }
     }
 
     protected static KeyManagerFactory buildKeyManagerFactory(X509Certificate[] certChainFile,
                                                     String keyAlgorithm, PrivateKey key,
                                                     String keyPassword, KeyManagerFactory kmf,
                                                     String keyStore)
             throws KeyStoreException, NoSuchAlgorithmException, IOException,
             CertificateException, UnrecoverableKeyException {
         if (keyAlgorithm == null) {
             keyAlgorithm = KeyManagerFactory.getDefaultAlgorithm();
         }
         char[] keyPasswordChars = keyStorePassword(keyPassword);
         KeyStore ks = buildKeyStore(certChainFile, key, keyPasswordChars, keyStore);
         return buildKeyManagerFactory(ks, keyAlgorithm, keyPasswordChars, kmf);
     }
 
     static KeyManagerFactory buildKeyManagerFactory(KeyStore ks,
                                                     String keyAlgorithm,
                                                     char[] keyPasswordChars, KeyManagerFactory kmf)
             throws KeyStoreException, NoSuchAlgorithmException, UnrecoverableKeyException {
         // Set up key manager factory to use our key store
         if (kmf == null) {
             if (keyAlgorithm == null) {
                 keyAlgorithm = KeyManagerFactory.getDefaultAlgorithm();
             }
             kmf = KeyManagerFactory.getInstance(keyAlgorithm);
         }
         kmf.init(ks, keyPasswordChars);
 
         return kmf;
     }
 
     static char[] keyStorePassword(String keyPassword) {
         return keyPassword == null ? EmptyArrays.EMPTY_CHARS : keyPassword.toCharArray();
     }
 }