| /* |
| * 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.jackrabbit.oak.spi.blob; |
| |
| import java.security.SecureRandom; |
| |
| import javax.crypto.Mac; |
| import javax.crypto.spec.SecretKeySpec; |
| |
| import org.apache.jackrabbit.core.data.DataIdentifier; |
| import org.apache.jackrabbit.core.data.DataStoreException; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import static org.apache.commons.codec.binary.Hex.encodeHexString; |
| |
| /** |
| */ |
| public abstract class AbstractSharedBackend implements SharedBackend { |
| private static Logger LOG = LoggerFactory.getLogger(AbstractSharedBackend.class); |
| |
| private static final String ALGORITHM = "HmacSHA1"; |
| |
| /** |
| * Cached copy of the reference key of this data store. Initialized in |
| * {@link #getReferenceKey()} when the key is first accessed. |
| */ |
| private byte[] referenceKey = null; |
| |
| |
| protected String getReferenceFromIdentifier(DataIdentifier identifier) { |
| try { |
| String id = identifier.toString(); |
| |
| Mac mac = Mac.getInstance(ALGORITHM); |
| mac.init(new SecretKeySpec(getReferenceKey(), ALGORITHM)); |
| byte[] hash = mac.doFinal(id.getBytes("UTF-8")); |
| |
| return id + ':' + encodeHexString(hash); |
| } catch (Exception e) { |
| LOG.error("Failed to hash identifier using MAC (Message Authentication Code) algorithm.", e); |
| } |
| return null; |
| } |
| |
| /** |
| * Returns the reference key of this backend. If one does not already |
| * exist, it is automatically created in an implementation-specific way. |
| * The default implementation simply creates a temporary random key that's |
| * valid only until the data store gets restarted. Subclasses can override |
| * and/or decorate this method to support a more persistent reference key. |
| * <p> |
| * This method is called only once during the lifetime of a backend |
| * instance and the return value is cached in memory, so it's no problem |
| * if the implementation is slow. |
| * |
| * @return reference key |
| * @throws DataStoreException if the key is not available |
| */ |
| public byte[] getOrCreateReferenceKey() throws DataStoreException { |
| byte[] referenceKeyValue = new byte[256]; |
| new SecureRandom().nextBytes(referenceKeyValue); |
| return referenceKeyValue; |
| } |
| |
| //-----------------------------------------------------------< private >-- |
| |
| /** |
| * Returns the reference key of this data store. Synchronized to |
| * control concurrent access to the cached {@link #referenceKey} value. |
| * |
| * @return reference key |
| * @throws DataStoreException if the key is not available |
| */ |
| private synchronized byte[] getReferenceKey() throws DataStoreException { |
| if (referenceKey == null) { |
| referenceKey = getOrCreateReferenceKey(); |
| } |
| return referenceKey; |
| } |
| } |