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GitHub - skypeopensource/skypeopensource2: Open source client for Skype Network based on reverse engineering


First in world self-made client to Skype Network based on reversing original Skype 5.5 client.

For now, only receiving and sending messages are supported.

Try to compile it with Visual Studio 2010 and test by youself or use already compiled binaries.


LGPL 3.0

A commercial license is also avaiable on request.

Updated 2016-11-06 07:30

Program still working OK. Some small bug with small reply on "get relay nodes" from supernode command.

Updated 2016-10-05 20:00

Program still working OK.

Updated 2016-09-21 20:00

Still working OK without any modifications.

Updated 2016-09-12 02:00

Program tested, protocol still working OK.

But due to heavy testing during news headlines, function Skypename to IP fail because of static ip.

Need change it and recompile as mention before.

Updated 2016-09-11 02:30

Still working OK without any modifications.

Updated 2016-09-08 20:00

Program tested, protocol still working OK.

But due heavy testing during news headlines, function Skypename to IP fail because of static ip used.

To workaround this problem, uncomment new ip address (the "good one") in this code:

    // main

    // good one

And recompile it.

You can also use this project to do it on linux. And use result strings as vcard to Vcard area in program GUI (but do fail resolv at first, its need to get public ip). I just tested it, it work good.

Updated 2016-09-07 19:00

Program tested, all function still working OK.

Updated 2016-09-06 15:00

Program still working OK.

Some additional info on usage:

If you got this error on black console:

pkt block crc32=00009C54
relay_connect_mode = 1
encode len: 0x0000044A

And this error in "Debug Data" area:

Message send failed. Ret code:-1


Then try to remove a_cred.txt file, close program and run again. Its some bug with bugged credentials. Which happens from time to time.

Updated 2016-09-05 15:00

Just check my program today. All functions working well, for now.

I guess, they decide to enable contact-list event servers for users. Good decision.

Updated 2016-09-05 01:00

Microsoft-Skype do something very weird with contact-list event servers. Like disable it for all users. I try to login using latests skype version for windows with empty profile and dont get back my contact list at all. Hm... But, anyway, its okay. This is format for contact list file (contacts.txt) used in my app, just put it in same dir and add yours skypeusers manually:






And so one.

Issue Statements (added 2016-09-04)

The README should clearly state:

Reply on issues

whether or not this client is a complete re-implementation

Yes. It's a complete re-implementation of proprietary Skype Network protocol.

whether or not it includes disassembled code from the other Skype clients

Well, maybe a little :) unpack-4142.c and pack-4142.c are HexRays decompiled code and should be rewritten but I don't have time for this now.

whether or not it is a clean-room reverse-engineered code, like Wine/ReactOS

No. Not clean room, not Chinese wall.

why the specified license is valid and legal to use for the project

It's my own code, I write it, I am the author of most code and I hold all copyright rights.

Well, except some login pieces (skyauth3/skype_login.c) which are copyrighted by Sean O'Neil from VEST Corporation in 2009 and RC4 reversing and implementation (skype_rc4.c/skype_rc4.h) also by Sean O'Neil.

what are the legal complications, if any, to developing the project and to using it personally or commercially

  1. The pack-4142.c/unpack41-42.c mentioned above.
  2. Also, it contains MIRACL for RSA and big numbers multiply arithmetics.

MIRACL Cryptographic SDK: Multiprecision Integer and Rational Arithmetic Cryptographic Library is a C software library that is widely regarded by developers as the gold standard open source SDK for elliptic curve cryptography (ECC).

For commercial usage and license send me an e-mail to


Protocol brief overview:

Release post:


Sources (same as on GitHub here):


Donate page:

Bitcoin: 1CfpkVuxZbyVw6ndJdF7W5ZpJ78AdvQJqy

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