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Life span of a Yubikey - how to tell if it is near?
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Author:  pine [ Sat Feb 26, 2011 6:03 am ]
Post subject:  Life span of a Yubikey - how to tell if it is near?
If I remember it correctly, from reading the Yubikey manuals, there is a mention of limited lifespan of each Yubikey.

The reason for this limited life span is, again from my memory, a register in it where each time a token is generated, its value will got incremented by 1. And that register is of course not infinite. It is like 5-7 years of life span if on average a couple of tokens generated per day?

My question is, is there any way to tell if it is approaching its end? I'd hope there is some kind of alert, maybe a special flashing of the LED, so we can have time to prepare for a new one instead of being locked out with an end-of-life Yubikey :?

Thanks in advance.
Author:  andlil [ Sat Feb 26, 2011 10:22 am ]
Post subject:  Re: Life span of a Yubikey - how to tell if it is near?
The end of life can be reset by reprogramming you yubikey, that of course means that you will have re-enroll your yubikey for your applications to function.

//A
Author:  odinsdream [ Wed May 04, 2011 7:19 pm ]
Post subject:  Re: Life span of a Yubikey - how to tell if it is near?
This article answers your question about lifetime:
Quote:
The next two bytes in our sequence, bytes 7 and 8, are used to store a session counter in nonvolatile memory. The counter starts at zero and is incremented each time the device is plugged in. Two bytes for the session counter allows for 2(2*8) = 65,536 sessions. In other words, you can plug in the Yubikey three times a day for almost 60 years before running out of session counters. Note that you can generate a significant number of OTPs during each session (see below).
Author:  freeAgent [ Thu Aug 16, 2012 7:11 pm ]
Post subject:  Re: Life span of a Yubikey - how to tell if it is near?
I was also wondering about this. I read through the article and wanted to summarize it using slightly different wording so someone can confirm if my understanding is correct:

*A Yubikey can be plugged in a total of 65,536 times before it has to be reset (and you have to reprogram all your applications with the new information
*Once you've plugged the Yubikey in, it can successfully generate OTPs for about 24 days
*You can use the Yubikey 255 times for every time it is plugged in during those 24 days (or until you unplug it)

I am not sure about the third bullet. It seems like you could theoretically generate infinite unique OTPs during those 24 days due to the timestamp + counter combination.
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