This HTML/Javascript simulator visualizes the cipherstream generation of the A5/1 cipher
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A5/1 cipher simulator written in HTML/Javascript

This simulator visualizes the internal algorithms of the broken A5/1 cipher, that was used in the GSM standard to encrypt the commmunication data.

We created the simulator for a project in the course "IT security for mobile systems" on the Trier University of Applied Sciences to understand how the A5/1 cipher exactly works. You can go over every step from the key initialization to the register initialization and finally to the cipherstream generation. The state change of the maj() function and of all 3 registers can be observed for each step. The used key is hardcoded in the file and can be changed of course.

The simulator is just for general understanding and our implementation is probably not absolute correct!


If you have any questions to this project, just ask me via email: