GSM A5/1 Cipher Generator

This program is designed to generate and decipher GSM A5/1 ciphertext.

Sources

This helpful PDF, which gives a roadmap on how to implement this algorithm

Briceno, Marc. "A pedagogical implementation of A5/1." http://www.scard.org. (via the Wayback Machine)

TODO

• Separate test cases into separate file (and make better ones)
• Offer to accept user input to generate ciphertext based on given plaintext and a key and frame number
• Offer to accept user input to decrypt ciphertext using given values or magic tables/brute force/...
• Write test cases and better documentation for above functionality

What I learned

During this project, I learned the basics of GSM and LFSR cryptography. Though GSM is infrequently used in the developed world, it's an important gateway to understanding future telecommunications protocol that builds on the flaws of GSM. I hope to expand on this knowledge in the future and hopefully implement better test cases and functionality when I get the chance.