Programmable hardware TOTP keys with the ability to synchronize time

We are pleased to announce a new line of programmable hardware TOTP keys from TOKEN2. The main innovation is the ability to synchronize the system clock hardware keys via the NFC API using special applications - at the moment is preparing a release for Android and Windows 10.

There are no applications for iOS yet: despite the fact that NFC chips are physically present on the latest iPhone models, Apple does not yet provide a public API for their use.

What is it for?

Unlike mobile TOTP applications, hardware keys do not have the ability to synchronize time over NTP, over a cellular network or radio signal: the device hardware keys are completely isolated and autonomous, and use a clock on their board as a source of accurate time. In 1933-1934 physicists Scheibe and Adelsberger of the Imperial Physics and Technology Institute in Berlin took up the possibilities of using the piezoelectric effect to measure time. It is this effect that underlies the system clock of the hardware keys. The accuracy of such hours varies from ± 0.3 to ± 1.1 s / day, depending on the quality. If this accuracy is sufficient for ordinary wristwatches, in hardware keys, the time difference more than a certain limit may lead to a failure in activation and / or authentication. This limit depends on the specific system (for example, Microsoft Azure MFA allows up to 600 seconds bias to both sides) when it comes to first registering a hardware key. Further, the process of synchronizing the bias during the use of the key for entry is already clearly described inRFC 6238


That is, if the authentication server complies with all RFC prescriptions, and if the key is used for authentication is not too rare, for example, at least a couple of times a year (the exact number can be calculated using the accuracy of the oscillator and the time offset allowed by the server), then time offsets will be taken into account on the server side and problems should arise. When using keys in such conditions, the time synchronization function is basically not needed.

However, the time synchronization function can be useful in the following cases:

• If the server implementation of TOTP does not follow RFC6238 recommendation # 6. One example of such an implementation is DUO :

  TOTP token drift and resynchronization are not supported. It is not necessary to work with the author, but may not have to

• If a batch of hardware keys was purchased a long time ago, but they had to be activated only after some time - in this case there is simply no synchronization mechanism in many systems.
• If the hardware key is used to log in less frequently than is needed for synchronization. For example, if a user wants to “copy” the same TOTP profile (more precisely, the secret secret key) to two devices: a) to a mobile application on the phone for everyday use and b) to a programmable hardware key as a backup for a rainy day . Thus, if this rainy day comes in 3-4 years, the hardware token will no longer be used precisely because of the time difference. And the battery on the token, which has not been turned on for a long time, almost does not lose capacity. Consequently, in this case, it is enough just to “set” the clock on them in order to return them to the system.