Samsung patents secure handoff method for 5G network management functions

1. A method by an access and mobility management function (AMF) for AMF reallocation in a communication system, the method comprising: receiving a registration request message from a user equipment (UE); obtaining a first security context for the UE from a previous AMF; transmitting, to a network slice selection function (NSSF), a first request message including at least one of a first parameter requesting a public key of an AMF to be reallocated or a second parameter requesting a token related to the AMF to be reallocated; receiving, from the NSSF, a first response message including information indicating a target AMF set and at least one of a public key of the target AMF set or the token; generating a security context container including a second security context for a target AMF based on the first security context; encrypting the security context container using the public key; transmitting the encrypted security context container and at least one of additional information related to encryption of the security context container and the token to the target AMF through a radio access network related to the UE; receiving a first registration request message from a first UE; obtaining a third security context for the first UE from a first previous AMF; transmitting, to the NSSF, a third request message including a third parameter requesting a public key of an AMF to be reallocated; receiving, from the NSSF, a third response message including information indicating a first target AMF set; transmitting, to a network repository function (NRF), a fourth request message including a fourth parameter requesting a token related to the AMF to be reallocated; receiving, from the NRF, a fourth response message including a token related to the first target AMF set; generating a first security context container including a fourth security context for a first target AMF based on the third security context; encrypting the first security context container using the public key; and transmitting the encrypted first security context container and at least one of additional information related to encryption of the first security context container and the token to the first target AMF through a first radio access network related to the first UE.