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1: /* 2: * SaslCramMD5.java 3: * Copyright (C) 2004 The Free Software Foundation 4: * 5: * This file is part of GNU inetlib, a library. 6: * 7: * GNU inetlib is free software; you can redistribute it and/or modify 8: * it under the terms of the GNU General Public License as published by 9: * the Free Software Foundation; either version 2 of the License, or 10: * (at your option) any later version. 11: * 12: * GNU inetlib is distributed in the hope that it will be useful, 13: * but WITHOUT ANY WARRANTY; without even the implied warranty of 14: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15: * GNU General Public License for more details. 16: * 17: * You should have received a copy of the GNU General Public License 18: * along with this library; if not, write to the Free Software 19: * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 20: * 21: * Linking this library statically or dynamically with other modules is 22: * making a combined work based on this library. Thus, the terms and 23: * conditions of the GNU General Public License cover the whole 24: * combination. 25: * 26: * As a special exception, the copyright holders of this library give you 27: * permission to link this library with independent modules to produce an 28: * executable, regardless of the license terms of these independent 29: * modules, and to copy and distribute the resulting executable under 30: * terms of your choice, provided that you also meet, for each linked 31: * independent module, the terms and conditions of the license of that 32: * module. An independent module is a module which is not derived from 33: * or based on this library. If you modify this library, you may extend 34: * this exception to your version of the library, but you are not 35: * obliged to do so. If you do not wish to do so, delete this 36: * exception statement from your version. 37: */ 38: 39: package gnu.inet.util; 40: 41: import java.io.UnsupportedEncodingException; 42: import java.security.MessageDigest; 43: import java.security.NoSuchAlgorithmException; 44: import javax.security.sasl.SaslClient; 45: import javax.security.sasl.SaslException; 46: 47: /** 48: * SASL mechanism for CRAM-MD5. 49: * 50: * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a> 51: */ 52: public class SaslCramMD5 53: implements SaslClient 54: { 55: 56: private String username; 57: private String password; 58: private boolean complete; 59: 60: public SaslCramMD5(String username, String password) 61: { 62: this.username = username; 63: this.password = password; 64: } 65: 66: public String getMechanismName() 67: { 68: return "CRAM-MD5"; 69: } 70: 71: public boolean hasInitialResponse() 72: { 73: return false; 74: } 75: 76: public byte[] evaluateChallenge(byte[] challenge) 77: throws SaslException 78: { 79: try 80: { 81: byte[] s = password.getBytes("US-ASCII"); 82: byte[] digest = hmac_md5(s, challenge); 83: byte[] r0 = username.getBytes("US-ASCII"); 84: byte[] r1 = new byte[r0.length + digest.length + 1]; 85: System.arraycopy(r0, 0, r1, 0, r0.length); // add username 86: r1[r0.length] = 0x20; // SPACE 87: System.arraycopy(digest, 0, r1, r0.length+1, digest.length); 88: complete = true; 89: return r1; 90: } 91: catch (UnsupportedEncodingException e) 92: { 93: String msg = "Username or password contains non-ASCII characters"; 94: throw new SaslException(msg, e); 95: } 96: catch (NoSuchAlgorithmException e) 97: { 98: String msg = "MD5 algorithm not available"; 99: throw new SaslException(msg, e); 100: } 101: } 102: 103: public boolean isComplete() 104: { 105: return complete; 106: } 107: 108: public byte[] unwrap(byte[] incoming, int off, int len) 109: throws SaslException 110: { 111: byte[] ret = new byte[len - off]; 112: System.arraycopy(incoming, off, ret, 0, len); 113: return ret; 114: } 115: 116: public byte[] wrap(byte[] outgoing, int off, int len) 117: throws SaslException 118: { 119: byte[] ret = new byte[len - off]; 120: System.arraycopy(outgoing, off, ret, 0, len); 121: return ret; 122: } 123: 124: public Object getNegotiatedProperty(String name) 125: { 126: return null; 127: } 128: 129: public void dispose() 130: { 131: } 132: 133: /** 134: * Computes a CRAM digest using the HMAC algorithm: 135: * <pre> 136: * MD5(key XOR opad, MD5(key XOR ipad, text)) 137: * </pre>. 138: * <code>secret</code> is null-padded to a length of 64 bytes. 139: * If the shared secret is longer than 64 bytes, the MD5 digest of the 140: * shared secret is used as a 16 byte input to the keyed MD5 calculation. 141: * See RFC 2104 for details. 142: */ 143: private static byte[] hmac_md5(byte[] key, byte[] text) 144: throws NoSuchAlgorithmException 145: { 146: byte[] k_ipad = new byte[64]; 147: byte[] k_opad = new byte[64]; 148: byte[] digest; 149: MessageDigest md5 = MessageDigest.getInstance("MD5"); 150: // if key is longer than 64 bytes reset it to key=MD5(key) 151: if (key.length>64) 152: { 153: md5.update(key); 154: key = md5.digest(); 155: } 156: // start out by storing key in pads 157: System.arraycopy(key, 0, k_ipad, 0, key.length); 158: System.arraycopy(key, 0, k_opad, 0, key.length); 159: // XOR key with ipad and opad values 160: for (int i=0; i<64; i++) 161: { 162: k_ipad[i] ^= 0x36; 163: k_opad[i] ^= 0x5c; 164: } 165: // perform inner MD5 166: md5.reset(); 167: md5.update(k_ipad); 168: md5.update(text); 169: digest = md5.digest(); 170: // perform outer MD5 171: md5.reset(); 172: md5.update(k_opad); 173: md5.update(digest); 174: digest = md5.digest(); 175: return digest; 176: } 177: 178: }