Section: 14.5 Temporary identities
Content: The Temporary identities (Pseudonyms and re-authentication identities) shall take the form of a NAI username as specified in clause 2.1 of the IETF RFC 4282 [53]. Temporary identity shall be generated as specified in clause 6.4.1 of 3GPP TS 33.234[ 3G security; Wireless Local Area Network (WLAN) interworking security ]  [55]. This part of the temporary identity shall follow the UTF-8 transformation format specified in IETF RFC 2279 [54] except for the following reserved hexadecimal octet value: FF. When the temporary identity username is coded with FF, this reserved value is used to indicate the special case when no valid temporary identity exists in the WLAN UE (see 3GPP TS 24.234[ 3GPP system to Wireless Local Area Network (WLAN) interworking; WLAN User Equipment (WLAN UE) to network protocols; Stage 3 ]  [48]). The network shall not allocate a temporary identity with the whole username coded with the reserved hexadecimal value FF. For EAP-AKA authentication, the username portion of the pseudonym identity shall be prepended with the single digit "2" and the username portion of the fast re-authentication identity shall be prepended with the single digit "4" as specified in clause 4.1.1.7 of IETF RFC 4187 [50]. For EAP-SIM authentication, the username portion of the pseudonym identity shall be prepended with the single digit "3" and the username portion of the fast re-authentication identity shall be prepended with the single digit "5" as specified in clause 4.2.1.7 of IETF RFC 4186 [51].