Experts are warning about potential security and usability concerns with the FIDO2 protocols. The warning comes in the wake of a new paper in the Cryptology ePrint Archive of the International Association for Cryptologic Research that suggests that FIDO2’s Client-to-Authenticator Protocol (CTAP2) may be vulnerable to man-in-the-middle-attacks, and a separate report that suggests that a lack of interoperability could make it difficult to carry credentials across platforms.
With regards to the former, the writers of the ‘Provable Security Analysis of FIDO2’ paper found that CTAP2 was performing an unauthenticated key exchange, and that the platform’s “pinToken” generation system would sometimes reuse the same credential for multiple interactions. The researchers recommended the use of more secure (and authenticated) binding practices to help close that security gap.
The other problem has more to do with how FIDO technology gets deployed, and the fact that tech giants like Apple, Google, and Microsoft all have their own authentication ecosystems. All three are members of the FIDO Alliance, and all three are taking steps to eliminate passwords.
In practice, that means that the companies are using device biometrics for identity verification, and then using that initial authentication event to speed up logins in apps and web browsers. The feature is comparable to a password manager, insofar as the device remembers the user and removes certain barriers while that person is at the helm. The big tech giants can also carry some of that utility across multiple devices through the cloud. For example, Apple could remember the facial biometrics of someone with an iPhone, and use that to streamline that person’s experience when they try to log into a Mac computer.
That latter feature is ultimately at the root of the problem. As long as a user stays on one ecosystem, it is relatively easy to transfer someone’s authentication passkeys. However, that is not the case if someone wants to switch from an iPhone to an Android device (for example). The current FIDO2 system allows people to swap credentials one application and account at a time, but does not have a mechanism for a secure and large-scale batch exchange.
As a result, changing between ecosystems is a more onerous and time-consuming process that could lock people into their current platform, even when they want to make a switch. That is currently not the case, since passwords tend to be easier to transfer.
For its part, the FIDO Alliance has stated that batch exporting will likely become a bigger priority in the future. The tech giants have similarly expressed an interest in interoperability. Having said that, the Alliance does not want to make it too easy to exchange passkeys, since that could create a mechanism that hackers could exploit if it is rolled out carelessly.