Feeds

London's tube demands faster-than-NFC ticketing

500 milliseconds not quick enough for the Underground

The essential guide to IT transformation

London Underground has been telling NFC World that existing NFC implementations just aren't fast enough, so it will be sticking with plastic cards for a while.

An Oyster card tapped against the reader takes between 200 and 300ms to authorise, before the gates snap open as a prelude to grabbing your bag as you pass though, but trials of Near Field Communications technology have shown authorisation times approaching a second, which NFC World reports is not fast enough for those dashing to get a tube.

Exactly where the bottleneck lies isn't clear: NFC Times fingers the SIM's ability to complete the encryption process, which could be improved with dedicated hardware, but the Single Wire Protocol (which connects the SIM to the NFC hardware) could also be to blame, along with the complexity of Oyster tariffs. What is clear is that the process is going to have go get a lot faster if the Underground is going to start accepting credit cards embedded in telephones, as it would like to.

Near Field Communications is a standard comprised of three components: an induction-powered tag, a reader capable of inducing power in similar tags, and a secure element for storing and using cryptographic keys for authentication. For ticketing the reader component isn't used, so it's the tag and the secure element that matter.

Network operators would like the secure element stored on the SIM, connected to the handset over the Single Wire Protocol (SWP), while handset manufacturers would prefer the element embedded in the handset and banks have so far shown a preference for it to be located in a removable SD Card. The only two handsets currently supporting NFC – Nokia's C7 and Google/Samsung's Nexus S – both support SWP, but also have embedded secure elements under the control of the manufacturers (or Google, in the latter case, we still don't know for sure).

The SIM is certainly capable of fast encryption: it is required to decrypt session keys, and cryptographic challenges from the network, enormously quickly, but that's using hardware designed for specific cryptographic algorithms, which is much easier than generic cryptography. The Oyster network is moving towards using DESFire, an update to the cracked MiFare platform, so NFC implementations that want to do fast Oyster transactions will need to support that protocol in hardware to achieve the speed necessary. The embedded component in the Nexus S is supplied by NXP Semiconductors, owners of DESFire, so it should be able to cope, but a secure element dropped into a SIM might struggle, and that's before credit cards are taken into account.

Oyster is contracted to provide ticketing to the Underground, but Transport For London would much prefer to collect the money itself, which means taking credit-card payments at the turnstile. In theory, a PayPass or PayWave (Mastercard and Visa respectively) card could be tapped against the reader, authorising the reader to contact the card-holder's bank and deduct the cost of the journey from the holder's account, but doing it in less than than half a second is tough.

And it's 500ms that London Underground is specifying as the cap, despite having previously said that 350ms is the longest it is prepared to wait. The convenience of mobile-phone credit-card payments on the tube is apparently worth waiting 150ms for, but not a millisecond more. ®

Secure remote control for conventional and virtual desktops

More from The Register

next story
Déjà vu: Virgin Media jacks up broadband prices
Screw copper phone lines, we're UNIQUE, bleats telco
NBN Co claims 96 mbps download speeds for FTTN trial
Umina trial also delivers 30 mbps uploads, but exact rig used not revealed
UK fuzz want PINCODES on ALL mobile phones
Met Police calls for mandatory passwords on all new mobes
Netflix swallows yet another bitter pill, inks peering deal with TWC
Net neutrality crusader once again pays up for priority access
New Sprint CEO says he will lower axe on staff – but prices come first
'Very disruptive' new rates to be revealed next week
EE: STILL Blighty's best mobe network, says 'Frappucino' Moore
Fresh round of network stats fisticuffs possibly on the cards here
US TV stations bowl sueball directly at FCC's spectrum mega-sale
Broadcasters upset about coverage and cost as they shift up and down the dials
ROAD TRIP! An FCC road trip – Leahy demands net neutrality debate across US
You crashed watchdog's site, now time to crash its ears
Google's so smart it's discovered SHARKS HAVE TEETH
Congratulations, world media, for rediscovering submarine cable armour
prev story

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
7 Elements of Radically Simple OS Migration
Avoid the typical headaches of OS migration during your next project by learning about 7 elements of radically simple OS migration.
BYOD's dark side: Data protection
An endpoint data protection solution that adds value to the user and the organization so it can protect itself from data loss as well as leverage corporate data.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?