| /* |
| * 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.pirk.utils; |
| |
| import java.security.MessageDigest; |
| import java.security.NoSuchAlgorithmException; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * Class for the PIR keyed hash |
| * <p> |
| * Defaults to java hashCode(); can optionally choose MD5, SHA-1, or SHA-256 |
| * |
| */ |
| public class KeyedHash |
| { |
| private static final Logger logger = LoggerFactory.getLogger(KeyedHash.class); |
| |
| /** |
| * Hash method that uses the java String hashCode() |
| */ |
| public static int hash(String key, int bitSize, String input) |
| { |
| int fullHash = (key + input).hashCode(); |
| |
| // Take only the lower bitSize-many bits of the resultant hash |
| int bitLimitedHash = fullHash; |
| if (bitSize < 32) |
| { |
| bitLimitedHash = (0xFFFFFFFF >>> (32 - bitSize)) & fullHash; |
| } |
| |
| return bitLimitedHash; |
| } |
| |
| /** |
| * Hash method to optionally specify a hash type other than the default java hashCode() hashType must be MD5, SHA-1, or SHA-256 |
| * |
| */ |
| public static int hash(String key, int bitSize, String input, String hashType) |
| { |
| int bitLimitedHash; |
| |
| try |
| { |
| MessageDigest md = MessageDigest.getInstance(hashType); |
| byte[] array = md.digest(input.getBytes()); |
| |
| int hashInt = fromByteArray(array); |
| bitLimitedHash = hashInt; |
| if (bitSize < 32) |
| { |
| bitLimitedHash = (0xFFFFFFFF >>> (32 - bitSize)) & hashInt; |
| } |
| logger.debug("hashInt = " + hashInt + " bitLimitedHash = " + bitLimitedHash); |
| |
| } catch (NoSuchAlgorithmException e) |
| { |
| logger.info(e.toString()); |
| bitLimitedHash = hash(key, bitSize, input); |
| } |
| |
| return bitLimitedHash; |
| } |
| |
| private static int fromByteArray(byte[] bytes) |
| { |
| return bytes[0] << 24 | (bytes[1] & 0xFF) << 16 | (bytes[2] & 0xFF) << 8 | (bytes[3] & 0xFF); |
| } |
| } |