Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF 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 * * http://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 org.apache.sshd.common.util; import java.security.KeyFactory; import java.security.KeyPairGenerator; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.security.NoSuchProviderException; import java.security.Signature; import javax.crypto.Cipher; import javax.crypto.KeyAgreement; import javax.crypto.Mac; import javax.crypto.NoSuchPaddingException; import org.bouncycastle.jce.provider.BouncyCastleProvider; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * TODO Add javadoc * * @author <a href="mailto:dev@mina.apache.org">Apache MINA SSHD Project</a> */ public class SecurityUtils { public static final String BOUNCY_CASTLE = "BC"; private static final Log LOG = LogFactory.getLog(SecurityUtils.class); private static String securityProvider = null; private static Boolean registerBouncyCastle; private static boolean registrationDone; public static synchronized void setSecurityProvider(String securityProvider) { SecurityUtils.securityProvider = securityProvider; registrationDone = false; } public static synchronized void setRegisterBouncyCastle(boolean registerBouncyCastle) { SecurityUtils.registerBouncyCastle = registerBouncyCastle; registrationDone = false; } public static synchronized String getSecurityProvider() { register(); return securityProvider; } public static synchronized boolean isBouncyCastleRegistered() { register(); return BOUNCY_CASTLE.equals(securityProvider); } private static void register() { if (!registrationDone) { if (securityProvider == null && (registerBouncyCastle == null || registerBouncyCastle)) { // Use an inner class to avoid a strong dependency from SshServer on BouncyCastle try { new BouncyCastleRegistration().run(); } catch (Throwable t) { if (registerBouncyCastle == null) { LOG.info("BouncyCastle not registered, using the default JCE provider"); } else { LOG.error("Failed to register BouncyCastle as the defaut JCE provider"); throw new RuntimeException("Failed to register BouncyCastle as the defaut JCE provider", t); } } } registrationDone = true; } } private static class BouncyCastleRegistration { public void run() throws Exception { if (java.security.Security.getProvider(BOUNCY_CASTLE) == null) { LOG.info("Trying to register BouncyCastle as a JCE provider"); java.security.Security.addProvider(new BouncyCastleProvider()); MessageDigest.getInstance("MD5", BOUNCY_CASTLE); KeyAgreement.getInstance("DH", BOUNCY_CASTLE); LOG.info("Registration succeeded"); } else { LOG.info("BouncyCastle already registered as a JCE provider"); } securityProvider = BOUNCY_CASTLE; } } public static synchronized KeyFactory getKeyFactory(String algorithm) throws NoSuchAlgorithmException, NoSuchProviderException { register(); if (getSecurityProvider() == null) { return KeyFactory.getInstance(algorithm); } else { return KeyFactory.getInstance(algorithm, getSecurityProvider()); } } public static synchronized Cipher getCipher(String transformation) throws NoSuchAlgorithmException, NoSuchPaddingException, NoSuchProviderException { register(); if (getSecurityProvider() == null) { return Cipher.getInstance(transformation); } else { return Cipher.getInstance(transformation, getSecurityProvider()); } } public static synchronized MessageDigest getMessageDigest(String algorithm) throws NoSuchAlgorithmException, NoSuchProviderException { register(); if (getSecurityProvider() == null) { return MessageDigest.getInstance(algorithm); } else { return MessageDigest.getInstance(algorithm, getSecurityProvider()); } } public static synchronized KeyPairGenerator getKeyPairGenerator(String algorithm) throws NoSuchAlgorithmException, NoSuchProviderException { register(); if (getSecurityProvider() == null) { return KeyPairGenerator.getInstance(algorithm); } else { return KeyPairGenerator.getInstance(algorithm, getSecurityProvider()); } } public static synchronized KeyAgreement getKeyAgreement(String algorithm) throws NoSuchAlgorithmException, NoSuchProviderException { register(); if (getSecurityProvider() == null) { return KeyAgreement.getInstance(algorithm); } else { return KeyAgreement.getInstance(algorithm, getSecurityProvider()); } } public static synchronized Mac getMac(String algorithm) throws NoSuchAlgorithmException, NoSuchProviderException { register(); if (getSecurityProvider() == null) { return Mac.getInstance(algorithm); } else { return Mac.getInstance(algorithm, getSecurityProvider()); } } public static synchronized Signature getSignature(String algorithm) throws NoSuchAlgorithmException, NoSuchProviderException { register(); if (getSecurityProvider() == null) { return Signature.getInstance(algorithm); } else { return Signature.getInstance(algorithm, getSecurityProvider()); } } }