Algorithm 5 The Challenge–Response Step 2.2 [SN]

Inputs:  $(\mathit{SE}-\mathit{AV})$       SN parse $(\mathit{SE}-\mathit{AV})$ as $(RAND,AUTN,HXRE{S}^{*})$       SN store $(RAND,HXRE{S}^{*})$ and sends $(RAND,AUTN)$ to UE    Outputs. SN sends $(RAND,AUTN)$ to UE.