We've long known that multifactor authentication provides stronger security over simple passwords, but a limited number of options, cost, interoperability issues, and the dread that IT pros feel at the idea of issuing users multiple tokens have put a damper on deployment. With its recently released Reference Architecture 2.0, the Initiative for Open Authentication, or OATH, hopes to allay these misgivings with an open standard to bring strong authentication to applications and services.
The operative word here is "standard." Systems based on OATH's architecture allow for interoperability among user tokens and a variety of services requiring authentication. The ultimate goal: a single token compatible with any number of services from different providers. This is a fantastic idea, but it's currently possible only in a limited way. Because the current token implementation is event-triggered, if a token is used with unconnected services, the event count for those services will not match the state of the token, causing authentication to fail. The only way to make the system work is for all services to use the same validation back end, thereby keeping token state consistent. One such service is VeriSign's Verified Identity Protection, or VIP. Charles Schwab and eBay are two high-profile users; customers need only a single token to authenticate to these and other VIP-managed online services.
For every open standard there are proprietary alternatives, and strong authentication is no exception. While RSA has been the closed-system market leader for quite a while, the multifactor authentication space is getting crowded. Entries include WiKID, which uses a mobile phone-based software token, and PhoneFactor, which sends an authentication code to users' phones. Still, this is one area where the open alternative has a real shot. OATH's membership list is large and varied. Besides VeriSign, the latest spec is integrated into products from AOL, BMC, Citrix, Entrust, Hewlett-Packard, IBM/Tivoli, Imprivata, SanDisk, and many more.
A BETTER WAY
Single-factor authentication using passwords is weak. One-time passwords improve the situation by generating a new password for each use. This was originally done by printing out a list of complex passwords and crossing off each as it's used. A difficult system at best, at worst a productivity killer for users who run out of passwords. Token-based systems improved on the process by using a key-fob electronic device to display the next needed password on an LCD screen. Problem is, these systems were somewhat pricey to deploy because a limited number of proprietary systems dominated the market. As a result of the interoperability inherent in the OATH open standard, however, we've seen vendors develop a swell of token options, including credit card-size tokens; USB-connected tokens; even purely software-based key generators that can run on mobile phones, eliminating the need to even carry a separate gizmo.
There are two ways to generate one-time passwords. The first is event-based, where the password changes each time one is used, as with the printed password list; the other produces a new password on a fixed schedule, which is how EMC/RSA SecurID tokens work. While it's not clear that one method is inherently better, an event-based password rotation is simpler and less expensive to implement. Time-based tokens must have fairly accurate clocks to change the password at the same time the server does, whereas event-triggered tokens need only process an algorithm each time the button is pressed to display the next password in the sequence. This means event-triggered tokens can also be smaller and last much longer, since they need to be powered only when used.