Java tutorial
/* * Copyright 2016 The Simple File Server Authors * * Licensed 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.sfs.encryption; import com.google.common.primitives.Longs; import java.lang.management.ManagementFactory; public final class SecureSecret { private byte[] salt; private byte[] encrypted; private final AlgorithmDef algorithmDef; public SecureSecret() { this.algorithmDef = AlgorithmDef.getPreferred(); this.salt = algorithmDef.generateSaltBlocking(); } public byte[] getClearBytes() { if (encrypted == null) { throw new IllegalStateException("encrypted cannot be null"); } if (salt == null) { throw new IllegalStateException("salt cannot be null"); } Algorithm algorithm = algorithmDef.create(getSecret(), salt); return algorithm.decrypt(encrypted); } public SecureSecret setClearBytes(byte[] clear) { encrypted = encrypt(clear); return this; } protected byte[] encrypt(byte[] clear) { if (clear == null) { return null; } Algorithm algorithm = algorithmDef.create(getSecret(), salt); return algorithm.encrypt(clear); } protected byte[] toBytes(long v) { return Longs.toByteArray(v); } protected byte[] getSecret() { byte[] secret = toBytes(ManagementFactory.getRuntimeMXBean().getStartTime()); return secret; } }