Term    　　   Explanation
AKA    　　　　Authentication and Key Agreement
B-TID    　　　Bootstrapping Transaction Identifier 
BSF   　　 　　　Bootstrapping Service Function
CA   　　      Certificate Authority
CK    　　     Cipher Key
GAA    　　     Generic Authentication Architecture
GBA    　　     Generic Bootstrapping Architecture
GBA_ME         ME-base GBA
GBA_U          GBA with UICC-based enhancements
HTTP    　　   Hypertext Transfer Protocol
HTTPS    　　  HTTP over TLS
HSS    　　    Home Subscriber System
IK    　　     Integrity Key
IMPI          IP Multimedia Private Identity
KDF    　　    Key Derivation Function
Ks_int_NAF    Derived key in GBA_U which remains on UICC
Ks_ext_NAF    Derived key in GBA_U
NAF    　　　　Network Application Function
TLS    　　　　Transport Layer Security
PKI    　　　　Public Key Infrastructure
SSC    　　　　Support for Subscriber Certificates