GSM Algorithms

GSM Association Security Documents

For further information on GSM visit the GSMWORLD site. This has full coverage maps, details of operators and much else.

The GSM Association manages the GSM algorithms and accepts requests for copies from qualified industry parties for:

• A5/1
• A5/2
• COMP 128:
  • -1 is the original version producing a 54 bit Kc;
  • -2 is the variant with a fix to get round the issues of -1;
  • -3 is a variant of -1 which produces a 64 bit Kc;
  • -4 is the the new version based on 3G Milenage, not yet available.
• A5/3 is now available and is due to be published on the Internet.