NTLM support in HttpClient 4.x
==============================

Currently HttpClient 4.0 does not provide support for the NTLM authentication
scheme out of the box and probably never will. The reasons for that are legal 
rather than technical.

Background
==========
NTLM is a proprietary authentication scheme developed by Microsoft and 
optimized for Windows operating system. 

Until year 2008 there was no official, publicly available, complete 
documentation of the protocol. Unofficial 3rd party protocol descriptions 
existed [1] as a result of reverse-engineering efforts. It was not really 
known whether the protocol based on the reverse-engineering were complete 
or even correct.

Microsoft published MS-NLMP [2] and MS-NTHT [3] specifications in February 
2008 as a part of its Interoperability Principles initiative [4]. 
Unfortunately, it is still not entirely clear whether NTLM encryption 
algorithms are covered by any patents held by Microsoft, which would make 
commercial users of open-source NTLM implementations liable for the use of 
Microsoft intellectual property.  
       
Enabling NTLM support in HttpClient 4.x
=======================================
The good news is HttpClient is fully NTLM capable right out of the box. 
HttpClient ships with the NTLM  authentication scheme, which, if configured 
to use an external NTLM engine, can handle NTLM challenges and authenticate 
against NTLM servers. 

-----------------------------------------------------------
public interface NTLMEngine {

    String generateType1Msg(
            String domain, 
            String workstation) throws NTLMEngineException;
    
    String generateType3Msg(
            String username,
            String password,
            String domain, 
            String workstation,
            String challenge) throws NTLMEngineException;

}   
-----------------------------------------------------------

Using Samba JCIFS as an NTLM engine
===================================
Follow these instructions to build an NTLMEngine implementation using JCIFS 
library

=========== !!!! DISCLAIMER !!!! ===========
HttpComponents project DOES _NOT_ SUPPORT the code provided below. Use it as
is at your own discretion.

* Download the latest jcifs library from the Samba web site [5]    
* Implement NTLMEngine interface
-----------------------------------------------------------
import jcifs.ntlmssp.Type1Message;
import jcifs.ntlmssp.Type2Message;
import jcifs.ntlmssp.Type3Message;
import jcifs.util.Base64;

import org.apache.http.impl.auth.NTLMEngine;
import org.apache.http.impl.auth.NTLMEngineException;

public class JCIFSEngine implements NTLMEngine {

    public String generateType1Msg(
            String domain, 
            String workstation) throws NTLMEngineException {

        Type1Message t1m = new Type1Message(
                Type1Message.getDefaultFlags(),
                domain,
                workstation);
        return Base64.encode(t1m.toByteArray());
    }

    public String generateType3Msg(
            String username, 
            String password, 
            String domain,
            String workstation, 
            String challenge) throws NTLMEngineException {
        Type2Message t2m;
        try {
            t2m = new Type2Message(Base64.decode(challenge));
        } catch (IOException ex) {
            throw new NTLMEngineException("Invalid Type2 message", ex);
        }
        Type3Message t3m = new Type3Message(
                t2m, 
                password, 
                domain, 
                username, 
                workstation);
        return Base64.encode(t3m.toByteArray());
    }

}
-----------------------------------------------------------
* Implement AuthSchemeFactory interface
-----------------------------------------------------------
import org.apache.http.auth.AuthScheme;
import org.apache.http.auth.AuthSchemeFactory;
import org.apache.http.impl.auth.NTLMScheme;
import org.apache.http.params.HttpParams;

public class NTLMSchemeFactory implements AuthSchemeFactory {

    public AuthScheme newInstance(final HttpParams params) {
        return new NTLMScheme(new JCIFSEngine());
    }

}
-----------------------------------------------------------
* Register NTLMSchemeFactory with the HttpClient instance you want to NTLM 
  enable.
-----------------------------------------------------------
    httpclient.getAuthSchemes().register("ntlm", new NTLMSchemeFactory());
-----------------------------------------------------------
* Set NTCredentials for the web server you are going to access.
-----------------------------------------------------------
    httpclient.getCredentialsProvider().setCredentials(
        new AuthScope("myserver", -1), 
        new NTCredentials("username", "password", "MYSERVER", "MYDOMAIN"));
-----------------------------------------------------------
* You are done.


Why this code is not distributed with HttpClient 
================================================
JCIFS is licensed under the Lesser General Public License (LGPL). This license 
is not compatible with the Apache Licenses under which all Apache Software is 
released. Lawyers of the Apache Software Foundation are currently investigating 
under which conditions Apache software is allowed to make use of LGPL software.

-----------------------------------------------------------
[1] http://davenport.sourceforge.net/ntlm.html
[2] http://download.microsoft.com/download/a/e/6/ae6e4142-aa58-45c6-8dcf-a657e5900cd3/%5BMS-NLMP%5D.pdf
[3] http://download.microsoft.com/download/a/e/6/ae6e4142-aa58-45c6-8dcf-a657e5900cd3/%5BMS-NTHT%5D.pdf
[4] http://www.microsoft.com/interop/principles/default.mspx
[5] http://jcifs.samba.org/