Java tutorial
/* * Copyright (C) 2018 LinkedIn Corp. All rights reserved. * * 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. */ package azkaban.crypto; import com.google.common.base.Preconditions; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.nio.charset.Charset; import org.apache.hadoop.fs.FileStatus; import org.apache.hadoop.fs.FileSystem; import org.apache.hadoop.fs.Path; import org.apache.hadoop.fs.permission.FsAction; import org.apache.hadoop.fs.permission.FsPermission; public class Decryptions { private static final FsPermission USER_READ_PERMISSION_ONLY = new FsPermission(FsAction.READ, FsAction.NONE, FsAction.NONE); public String decrypt(final String cipheredText, final String passphrasePath, final FileSystem fs) throws IOException { Preconditions.checkNotNull(cipheredText); Preconditions.checkNotNull(passphrasePath); final Path path = new Path(passphrasePath); Preconditions.checkArgument(fs.exists(path), "File does not exist at " + passphrasePath); Preconditions.checkArgument(fs.isFile(path), "Passphrase path is not a file. " + passphrasePath); final FileStatus fileStatus = fs.getFileStatus(path); Preconditions.checkArgument(USER_READ_PERMISSION_ONLY.equals(fileStatus.getPermission()), "Passphrase file should only have read only permission on only user. " + passphrasePath); final Crypto crypto = new Crypto(); try (BufferedReader br = new BufferedReader( new InputStreamReader(fs.open(path), Charset.defaultCharset()))) { final String passphrase = br.readLine(); final String decrypted = crypto.decrypt(cipheredText, passphrase); Preconditions.checkNotNull(decrypted, "Was not able to decrypt"); return decrypted; } } }