do U know a bout #comp_128 algorithm in mobile authentication 

authentication process using A3 and A8 algorithms 

comp 128 is a confidential algorithm operated in your mobile to extract SRES and KC ( which used to encrypt your data )

COMP128 is an implementation of the A3 and A8 algorithms defined in the GSM standard.

A3 is used to authenticate the mobile station to the network. A8 is used to generate the session key used by the A5 algorithm to encrypt the data transmitted between the mobile station and the BTS

this is the algorithm 

comp128 : RAND, Ki -> SRES, Kc{x[32]: array of bytesbit[128]: array of bitsm, n, y, z: integers

x[16..31] := RANDfor i := 1 to 8x[0..15] := Kifor j := 0 to 4for k := 0 to 2j-1for l := 0 to 24-j-1m := l + k * 25-jn := m + 24-jy := (x[m] + 2 * x[n]) mod 29-jz := (2 * x[m] + x[n]) mod 29-jx[m] := Tj[y]x[n] := Tj[z] for j := 0 to 31for k := 0 to 3bit[4 * j + k] := x[j]3-k

if i < 8 for j := 0 to 15for k := 0 to 7x[j + 16]7-k := bit[((8 * j + k) * 17) mod 128]SRES := bit[0..31]Kc := bit[74..127] \| 00000000002}