 the AS SMC to the UE; the UE replies with the AS security mode complete message. 3.9.6.3 Security Interworking The major challenge in security during handovers to other radio networks is how the security algorithms, KDFs, and keys are handled. 3GPP has defined the security interworking procedures in TS 36.300 and 33.401. The details of security interworking between EPS and non-3GPP systems are still under study. At inter eNodeB handovers, new eNodeB-specific keys may be derived by the source and/or destination eNodeB. Keys are bound to specific algorithms, SO when changing MME or eNodeB, a change of algorithm can occur. This should be reported to the UE which would require new derivation of keys both at the destination MME or eNodeB and the UE. Since the user plane is encrypted in the eNodeB for over-the-air downlink transmission, changing the Serving GW does not imply any update of security keying material unless accompanied by inter eNodeB handover. Inter-RAT handover from UTRAN to E-UTRAN is only supported after activation of integrity pro- tection in UTRAN. For E-UTRAN to UTRAN/GERAN mobility, the MME derives and transfers to the SGSN a confidentially key and an integrity key derived from KASME and other input parameters as specified in 3GPP TS 33.401. Based on this information, the SGSN can in turn derive appropriate keys to be used in the target RAN. Similarly for UTRAN/GERAN to E-UTRAN mobility, the SGSN derives and transfers to the MME a confidentially key and an integrity key CK and IK. Based on this information and other input parameters as specified in 3GPP TS 33.401, the MME and UE can in turn derive KASME. 3.9.7 MBMS Multimedia Broadcast Multimedia Service is a uni-directional point-to-multipoint service where data is transmitted from a single source entity to multiple recipients. 3GPP Release 8 introduced E-MBMS (Enhanced MBMS) to support high fidelity TV and broadcast services using EPS. In 3GPP Release 7 MBSFN (MBMS Single Frequency Network) feature was added which means that a dedicated carrier 