/*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.mobicents.ipbx.session.security;
import java.security.*;
import org.apache.log4j.Logger;
/**
* The class takes standard Http Authentication details and returns a response
* according to the MD5 algorithm
*
* @author Emil Ivov
*/
public class MessageDigestResponseAlgorithm
{
private static final Logger logger
= Logger.getLogger(MessageDigestResponseAlgorithm.class.getName());
/**
* Calculates an http authentication response in accordance with rfc2617.
* <p>
* @param algorithm a string indicating a pair of algorithms (MD5 (default),
* or MD5-sess) used to produce the digest and a checksum.
* @param username_value username_value (see rfc2617)
* @param realm_value A string that has been displayed to the user in order
* to determine the context of the username and password to use.
* @param passwd the password to encode in the challenge response.
* @param nonce_value A server-specified data string provided in the
* challenge.
* @param cnonce_value an optional client-chosen value whose purpose is
* to foil chosen plaintext attacks.
* @param method the SIP method of the request being challenged.
* @param digest_uri_value the value of the "uri" directive on the
* Authorization header in the request.
* @param entity_body the entity-body
* @param qop_value Indicates what "quality of protection" the client has
* applied to the message.
* @param nc_value the hexadecimal count of the number of requests
* (including the current request) that the client has sent with the nonce
* value in this request.
* @return a digest response as defined in rfc2617
* @throws NullPointerException in case of incorrectly null parameters.
*/
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)
{
logger.debug("trying to authenticate using : " + algorithm + ", "
+ username_value + ", " + realm_value + ", " + (passwd != null
&& passwd.trim().length() > 0) + ", " + nonce_value + ", "
+ nc_value + ", " + cnonce_value + ", " + method + ", "
+ digest_uri_value + ", " + entity_body + ", " + 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 = 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 + ":" + H(entity_body);
}
String request_digest = null;
if( cnonce_value != null
&& qop_value != null
&& nc_value!=null
&& (qop_value.equalsIgnoreCase("auth")
|| qop_value.equalsIgnoreCase("auth-int")))
{
request_digest = KD ( H(A1), nonce_value
+ ":" + nc_value
+ ":" + cnonce_value
+ ":" + qop_value
+ ":" + H(A2)
);
}
else
{
request_digest = KD(H(A1), nonce_value + ":" + 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 toHexString(digest.digest(data.getBytes()));
}
catch (NoSuchAlgorithmException ex)
{
//shouldn't happen
logger.error("Failed to instantiate an MD5 algorithm", ex);
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 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++] = toHex[ (b[i] >> 4) & 0x0F];
c[pos++] = toHex[b[i] & 0x0f];
}
return new String(c);
}
}