algorithm 8 (A8)
The A8 algorithm is used in GSM networks to generate the cipher key( Kc) for voice data encryption. Like A3, A8 is not standardized and is defined by the network operator. Like the A3 algorithm, the A8 algorithm is located on the SIM card and in the Authentication Center( AC) of the GSM network. The A3/A8 ratio is referred to as COMP128.