package org.voicebridge;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
/**
* The class takes standard Http Authentication details and returns a response
* according to the MD5 algorithm
*
* @author Emil Ivov < emcho@dev.java.net >
* @version 1.0
*/
public class MessageDigestAlgorithm {
/**
* Calculates a response an http authentication response in accordance with
* rfc2617.
*
* @param algorithm MD5 or MD5-sess)
* @param username_value username_value (see rfc2617)
* @param realm_value realm_value
* @param passwd passwd
* @param nonce_value nonce_value
* @param cnonce_value cnonce_value
* @param Method method
* @param digest_uri_value uri_value
* @param entity_body entity_body
* @param qop_value qop
* @return a digest response as defined in rfc2617
* @throws NullPointerException in case of incorrectly null parameters.
*/
public static String calculateResponse(String algorithm, String username_value,
String realm_value, String passwd, String nonce_value,
String nc_value, String cnonce_value, String Method,
String digest_uri_value, String entity_body, String qop_value) {
if (username_value == null || realm_value == null || passwd == null
|| Method == null || digest_uri_value == null
|| nonce_value == null)
throw new NullPointerException(
"Null parameter to MessageDigestAlgorithm.calculateResponse()");
// The following follows closely the algorithm for generating a response
// digest as specified by rfc2617
String A1 = null;
if (algorithm == null || algorithm.trim().length() == 0
|| algorithm.trim().equalsIgnoreCase("MD5")) {
A1 = username_value + ":" + realm_value + ":" + passwd;
}
else {
if (cnonce_value == null || cnonce_value.length() == 0)
throw new NullPointerException(
"cnonce_value may not be absent for MD5-Sess algorithm.");
A1 = MessageDigestAlgorithm.H(username_value + ":" + realm_value + ":" + passwd) + ":"
+ nonce_value + ":" + cnonce_value;
}
String A2 = null;
if (qop_value == null || qop_value.trim().length() == 0
|| qop_value.trim().equalsIgnoreCase("auth")) {
A2 = Method + ":" + digest_uri_value;
}
else {
if (entity_body == null)
entity_body = "";
A2 = Method + ":" + digest_uri_value + ":" + MessageDigestAlgorithm.H(entity_body);
}
String request_digest = null;
if (cnonce_value != null && qop_value != null
&& (qop_value.equals("auth") || (qop_value.equals("auth-int")))) {
request_digest = MessageDigestAlgorithm.KD(MessageDigestAlgorithm.H(A1), nonce_value + ":" + nc_value + ":"
+ cnonce_value + ":" + qop_value + ":" + MessageDigestAlgorithm.H(A2));
}
else {
request_digest = MessageDigestAlgorithm.KD(MessageDigestAlgorithm.H(A1), nonce_value + ":" + MessageDigestAlgorithm.H(A2));
}
return request_digest;
}
/**
* Defined in rfc 2617 as H(data) = MD5(data);
*
* @param data data
* @return MD5(data)
*/
private static String H(String data) {
try {
MessageDigest digest = MessageDigest.getInstance("MD5");
return MessageDigestAlgorithm.toHexString(digest.digest(data.getBytes()));
}
catch (NoSuchAlgorithmException ex) {
// shouldn't happen
return null;
}
}
/**
* Defined in rfc 2617 as KD(secret, data) = H(concat(secret, ":", data))
*
* @param data data
* @param secret secret
* @return H(concat(secret, ":", data));
*/
private static String KD(String secret, String data) {
return MessageDigestAlgorithm.H(secret + ":" + data);
}
// the following code was copied from the NIST-SIP instant
// messenger (its author is Olivier Deruelle). Thanks for making it public!
/**
* to hex converter
*/
private static final char[] toHex = {'0', '1', '2', '3', '4', '5', '6',
'7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
/**
* Converts b[] to hex string.
*
* @param b
* the bte array to convert
* @return a Hex representation of b.
*/
private static String toHexString(byte b[]) {
int pos = 0;
char[] c = new char[b.length * 2];
for (int i = 0; i < b.length; i++) {
c[pos++] = MessageDigestAlgorithm.toHex[(b[i] >> 4) & 0x0F];
c[pos++] = MessageDigestAlgorithm.toHex[b[i] & 0x0f];
}
return new String(c);
}
}