001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.commons.codec.digest; 018 019import java.util.Random; 020 021/** 022 * Base64 like method to convert binary bytes into ASCII chars. 023 * 024 * TODO: Can Base64 be reused? 025 * 026 * <p> 027 * This class is immutable and thread-safe. 028 * </p> 029 * 030 * @version $Id: B64.java 1435550 2013-01-19 14:09:52Z tn $ 031 * @since 1.7 032 */ 033class B64 { 034 035 /** 036 * Table with characters for Base64 transformation. 037 */ 038 static final String B64T = "./0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; 039 040 /** 041 * Base64 like conversion of bytes to ASCII chars. 042 * 043 * @param b2 044 * A byte from the result. 045 * @param b1 046 * A byte from the result. 047 * @param b0 048 * A byte from the result. 049 * @param outLen 050 * The number of expected output chars. 051 * @param buffer 052 * Where the output chars is appended to. 053 */ 054 static void b64from24bit(final byte b2, final byte b1, final byte b0, final int outLen, 055 final StringBuilder buffer) { 056 // The bit masking is necessary because the JVM byte type is signed! 057 int w = ((b2 << 16) & 0x00ffffff) | ((b1 << 8) & 0x00ffff) | (b0 & 0xff); 058 // It's effectively a "for" loop but kept to resemble the original C code. 059 int n = outLen; 060 while (n-- > 0) { 061 buffer.append(B64T.charAt(w & 0x3f)); 062 w >>= 6; 063 } 064 } 065 066 /** 067 * Generates a string of random chars from the B64T set. 068 * 069 * @param num 070 * Number of chars to generate. 071 */ 072 static String getRandomSalt(final int num) { 073 final StringBuilder saltString = new StringBuilder(); 074 for (int i = 1; i <= num; i++) { 075 saltString.append(B64T.charAt(new Random().nextInt(B64T.length()))); 076 } 077 return saltString.toString(); 078 } 079}