Section: 6.8.1.2 R99+ HLR/AuC
Content: Upon receipt of an authentication data request from a R99+ VLR/SGSN for a UMTS subscriber, a R99+ HLR/AuC shall send quintets, generated as specified in 6.3. Upon receipt of an authentication data request from a R98- VLR/SGSN for a UMTS subscriber, a R99+ HLR/AuC shall send triplets, derived from quintets using the following conversion functions: a) c1: RAND[GSM] = b) c2: SRES[GSM] = XRES*1 xor XRES*2 xor XRES*3 xor XRES*4 c) c3: Kc[GSM] = CK1 xor CK2 xor IK1 xor IK2 whereby XRES* is 16 octets long and XRES* = XRES if XRES is 16 octets long and XRES* = XRES || 0...0 if XRES is shorter than 16 octets, XRES*i are all 4 octets long and XRES* = XRES*1 || XRES*2 || XRES*3 || XRES*4, CKi and IKi are both 64 bits long and CK = CK1 || CK2 and IK = IK1 || IK2