Using your mobile phone account to pay for your use of public Wi-Fi hotspots should become rather easier thanks to the publication of a 'universal' smart card specification that can be used by WLAN providers to authorise WLAN access.

Developed by the WLAN Smart Card Consortium, the WLAN-SIM 1.0 specification also details how smart card technology can be used to allow users to roam seamlessly from hotspot to hotspot.

Essentially, the smart card is the wireless networking equivalent of a phone SIM card. It identifies the user, allowing the hotspot owner's back-end system to provide access to the network and trust that they will receive payment from the wireless ISP (WISP) the user has subscribed to.

According to the Consortium, the specification builds on existing standards, including 802.1x and EAP for authentication and WPA (Wi-Fi Protected Access) for data encryption.

Most - if not all - public hotspots don't use encryption keys because of the complexity of setting them up on the user's computer. New keys are needed for each hotspot the user will connect to. The Consortium hopes its specification will permit the easy application of keys to allow hotspot providers to guarantee data security without the hassle of forcing non-technical users to configure their software manually.

Dan Cunningham, Chairman of the Consortium's Business Committee, the specification provides a "go to market" opportunity for carriers, and hotspot aggregators and owners to "commercialise WLAN such as Wi-Fi hotspots with smart card security and roaming capabilities".

The WLAN-SIM specification covers the smart card technology used as the basis for the system and how the card can talk to the hotspot provider's back-end security, access and billing systems. Now, the Consortium will work on a standard methodology for connecting and using the smart card with the user's hardware, including notebooks and cellphones, which act as a medium for the authentication process.

The organisation is also developing the specification to meet the needs of enterprises looking to deploy smart cards as the basis for authentication on their own, private networks. Potentially, that will allow staff to connect as easily to the company LAN via a public network as they can through a direct link, at the same time as allowing the public access to be billed according to the company's contract with its wireless ISP.

The Consortium is also working on a specification to allow mobile phone networks to integrate such technology with their own mobile SIMs.

Among the 23 members of the WLAN Smart Card Consortium is Visa, which opens the possibility that it might integrate the specification into its own smart card technology, allowing users to log on to a hotspot and have payment billed directly and automatically to their credit card. ®