001package org.eclipse.aether.util; 002 003/* 004 * Licensed to the Apache Software Foundation (ASF) under one 005 * or more contributor license agreements. See the NOTICE file 006 * distributed with this work for additional information 007 * regarding copyright ownership. The ASF licenses this file 008 * to you under the Apache License, Version 2.0 (the 009 * "License"); you may not use this file except in compliance 010 * with the License. You may obtain a copy of the License at 011 * 012 * http://www.apache.org/licenses/LICENSE-2.0 013 * 014 * Unless required by applicable law or agreed to in writing, 015 * software distributed under the License is distributed on an 016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 017 * KIND, either express or implied. See the License for the 018 * specific language governing permissions and limitations 019 * under the License. 020 */ 021 022import java.nio.charset.StandardCharsets; 023import java.security.MessageDigest; 024import java.security.NoSuchAlgorithmException; 025 026/** 027 * A simple digester utility for Strings. Uses {@link MessageDigest} for requested algorithm. Supports one-pass or 028 * several rounds of updates, and as result emits hex encoded String. 029 * 030 * @since 1.9.0 031 */ 032public final class StringDigestUtil 033{ 034 private final MessageDigest digest; 035 036 /** 037 * Constructs instance with given algorithm. 038 * 039 * @see #sha1() 040 * @see #sha1(String) 041 */ 042 public StringDigestUtil( final String alg ) 043 { 044 try 045 { 046 this.digest = MessageDigest.getInstance( alg ); 047 } 048 catch ( NoSuchAlgorithmException e ) 049 { 050 throw new IllegalStateException( "Not supported digest algorithm: " + alg ); 051 } 052 } 053 054 /** 055 * Updates instance with passed in string. 056 */ 057 public StringDigestUtil update( String data ) 058 { 059 if ( data != null && !data.isEmpty() ) 060 { 061 digest.update( data.getBytes( StandardCharsets.UTF_8 ) ); 062 } 063 return this; 064 } 065 066 /** 067 * Returns the digest of all strings passed via {@link #update(String)} as hex string. There is no state preserved 068 * and due implementation of {@link MessageDigest#digest()}, same applies here: this instance "resets" itself. 069 * Hence, the digest hex encoded string is returned only once. 070 * 071 * @see MessageDigest#digest() 072 */ 073 public String digest() 074 { 075 return ChecksumUtils.toHexString( digest.digest() ); 076 } 077 078 /** 079 * Helper method to create {@link StringDigestUtil} using SHA-1 digest algorithm. 080 */ 081 public static StringDigestUtil sha1() 082 { 083 return new StringDigestUtil( "SHA-1" ); 084 } 085 086 /** 087 * Helper method to calculate SHA-1 digest and hex encode it. 088 */ 089 public static String sha1( final String string ) 090 { 091 return sha1().update( string ).digest(); 092 } 093}