A3 AUTHENTICATION

GSM Glossary

GSM — A3 Authentication

 

 

 

 

 

 

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Information on A3 Authentication

The A3 algorithm is used by a GSM network to authenticate a GSM mobile phone. The GSM A3 algorithm is a one-way function implemented in the subscriber identity module (SIM).
     For roaming, the authentication center (AUC) of the home network provides three security parameters (R, SRES, KC):

  • R: 128-bit random number challenge, uniquely generated for each authentication
  • Ki: mobile’s fixed 128-bit secret key
  • SRES: 32-bit response to challenge
    • Each GSM network is free to choose its own A3 algorithm.


    Other topics in our resources on GSM related to A3 Authentication include: 
     
  • GSM security
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