News : RC5 Mailing List

I have installed a mailing list that treats the Luxembourg RC5 effort. To subscribe, send E-mail to [email protected] and type "subscribe rc5" (without the quotation marks) in the body of your message.

[ General Info ] [ RC5 Luxembourg Effort ] [ How to join the team ] [ French doc with screen shots ]
[ Current list of participants ]

What is the RC5 challenge ?

Information taken from

In order to try to beat the current RSA Secret-Key Challenge, many people on the net have been using their computer's idle processing time to help crack the code. This will require testing at most 2^64 keys to determine the correct one. We are working on the contest on the RSA Contest Page with the identifier RC5-32/12/8 (the fifth from the top).

The Bovine RC5 Effort was formed to take the responsibilities of coordinating and maintaining the RC5 servers that are needed to distribute key blocks to work on to all of the participating client programs. To combat the network traffic and reliability problems, our effort depends heavily on multiple proxy servers so that network load can be distributed much more evenly. The proxy servers are in constant communication with each other to prevent duplicated work from being done.

To accomplish this great computational task, we need you to help out by running a special client program on your computer, and allow it to connect to one of our coordinating proxy servers. When the client program runs, your computer will be assigned a block of 268,435,456 keys to test and indicate if a solution was found. Most typical computers can finish one block of this size in about 40 minutes, though it will depend on the speed of your CPU. The more computers we have working together, the faster the combined effort will be. Any machine with a reliable connection to the Internet will work.

The RC5 Luxembourg effort

The RC5 Luxembourg Effort is a team created by myself in an attempt to coordinate Luxembourg's spare CPU cycles.

For those of you already familiar with the RC5 concept, please move to and get yourself a client for your platform. Then join team number 3185, RC5 Luxembourg Effort.
Click here to jump to the v2 clients page, and get your copy.

For those of you not familiar with the RC5 challenge, let me try to explain what it basically deals with.

RSA Labs, who are developing encryption algorithms etc, have issued a contest to reward the person or institution that is able to crack one of their 64bit keys. Cracking such a key means testing an incredibly large number of possibilities, and this cannot possibly be done with a single computer - it would take several hundred years. has therefore developed a system that allows each and every computer with a reliable Internet connection (either permanent, or dial-up) to participate in the calculation effort.

This is achieved through the following system : each participating computer runs a special software program, called hereafter "client". The client connects to one in a series of big servers to fetch some keyblocks, evaluates the keys contained therein, and sends the results back to the big server. Hence the idea of distributed processing power, as the processing load is distributed over several thousand (or more) CPU's, worldwide.

The software that lets you participate is a so called "v2 client", available from's website. Download a client for your platform (almost every platform is supported), and configure it. Configuration is straight-forward. For those of you not so fimiliar with english documentation, I have documented a very basic step-by-step install in french HERE.

IMPORTANT Once you have downloaded your client, and you are doing the setup, please set the DES buffers both to 0. The DES key has already been found.

Please direct any questions to .
Webmasters : Please feel free to copy the "cow-on-lux" .GIF file to your website, and make a link to this page. Thank you !

How to join the Luxembourg Team

Here is a step-by-step instruction on how to join the Luxembourg team. Please notice that to join a team, you will have to wait one or two days counting from your first server connection.

1. Connect to and click on the "Statistics".
2. Click on the Project Statistics for project RC5-64.
3. Search for your individual E-mail, using the input form.
4. Click on your e-mail.
5. On the bottom of the screen, you will see a button. Click it, and you will be sent a password that lets you administrate your account.Don't loose it!
6. Repeat the above steps. You will now see a button that lets you edit your settings.
7. Edit your settings, and type 3185 in the "Team Affiliation" box. Voila !
8. If you wish, you can place this GIF file on your homepage. Please make it a link to these pages !

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