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Java > Open Source Codes > org > appfuse > util > StringUtil


1 package org.appfuse.util;
2
3 import java.io.IOException JavaDoc;
4 import java.security.MessageDigest JavaDoc;
5
6 import org.apache.commons.logging.Log;
7 import org.apache.commons.logging.LogFactory;
8
9
10 /**
11  * String Utility Class This is used to encode passwords programmatically
12  *
13  * <p>
14  * <a h
15  * ref="StringUtil.java.htm"><i>View Source</i></a>
16  * </p>
17  *
18  * @author <a HREF="mailto:matt@raibledesigns.com">Matt Raible</a>
19  */
20 public class StringUtil {
21     //~ Static fields/initializers =============================================
22
23     private final static Log log = LogFactory.getLog(StringUtil.class);
24
25     //~ Methods ================================================================
26
27     /**
28      * Encode a string using algorithm specified in web.xml and return the
29      * resulting encrypted password. If exception, the plain credentials
30      * string is returned
31      *
32      * @param password Password or other credentials to use in authenticating
33      * this username
34      * @param algorithm Algorithm used to do the digest
35      *
36      * @return encypted password based on the algorithm.
37      */
38     public static String JavaDoc encodePassword(String JavaDoc password, String JavaDoc algorithm) {
39         byte[] unencodedPassword = password.getBytes();
40
41         MessageDigest JavaDoc md = null;
42
43         try {
44             // first create an instance, given the provider
45 md = MessageDigest.getInstance(algorithm);
46         } catch (Exception JavaDoc e) {
47             log.error("Exception: " + e);
48
49             return password;
50         }
51
52         md.reset();
53
54         // call the update method one or more times
55 // (useful when you don't know the size of your data, eg. stream)
56 md.update(unencodedPassword);
57
58         // now calculate the hash
59 byte[] encodedPassword = md.digest();
60
61         StringBuffer JavaDoc buf = new StringBuffer JavaDoc();
62
63         for (int i = 0; i < encodedPassword.length; i++) {
64             if ((encodedPassword[i] & 0xff) < 0x10) {
65                 buf.append("0");
66             }
67
68             buf.append(Long.toString(encodedPassword[i] & 0xff, 16));
69         }
70
71         return buf.toString();
72     }
73
74     /**
75      * Encode a string using Base64 encoding. Used when storing passwords
76      * as cookies.
77      *
78      * This is weak encoding in that anyone can use the decodeString
79      * routine to reverse the encoding.
80      *
81      * @param str
82      * @return String
83      */
84     public static String JavaDoc encodeString(String JavaDoc str) {
85         sun.misc.BASE64Encoder encoder = new sun.misc.BASE64Encoder();
86         return encoder.encodeBuffer(str.getBytes()).trim();
87     }
88
89     /**
90      * Decode a string using Base64 encoding.
91      *
92      * @param str
93      * @return String
94      */
95     public static String JavaDoc decodeString(String JavaDoc str) {
96         sun.misc.BASE64Decoder dec = new sun.misc.BASE64Decoder();
97         try {
98             return new String JavaDoc(dec.decodeBuffer(str));
99         } catch (IOException JavaDoc io) {
100             throw new RuntimeException JavaDoc(io.getMessage(), io.getCause());
101         }
102     }
103 }
104
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