[Cryptography] Do timing attacks matter?

[Nanitous]

> On 3 Sep 2024, at 21:13, Jerry Leichter <leichter at lrw.com> wrote:
> 
> We've been discussing this recently, and ... the following just appeared:
> 
> https://arstechnica.com/security/2024/09/yubikeys-are-vulnerable-to-cloning-attacks-thanks-to-newly-discovered-side-channel/
> 
> Summary:  Yubikeys, and a bunch of other devices that use a commonly available chipset and library, are vulnerable to an attack because of a non-constant-time implementation of the Euclidean algorithm.  The attack relies on physical possession of the device and makes it possible to clone it or (sometimes?) extract the internal private key.  They've demonstrated that possession for half an hour is enough.  The detailed report - at https://ninjalab.io/wp-content/uploads/2024/09/20240903_eucleak.pdf - shows that their method of getting at the traces requires disassembling - hence effectively destroying - a Yubikey.
> 
> A practical real-world attack?  Not quite, but rather close.
> 
>                                                        -- Jerry
> 
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The problem is in the cloning. The EM-probe needs to be very close the silicon surface, the Yubi-key must be “opened” destructively.

So, what security policy ameliorates this? 

1.1 If your Yubikey is lost (i.e. you don’t have it your possession anymore), you need to notify your security team without delay and that team will deregister the associated key in a timely fashion.
1.2. If your Yubikey is damaged in any way (visibly and/or “doesn’t seem to work”), you need to return the Yubi key without delay to your organisation’ s issuer, which decommissions it in a timely fashion.

Well, these should already be in place, isn't it?

Oh, and don’t forget the security policies when these policies are not met in a timely fashion etc etc ;-) 

/Twan van der Schoot.


—
Twan van der Schoot
Bezembinder 86
2401 HN  Alphen aan den Rijn
email : twanvds at xs4all.nl
mobile: 06-15052501
website: http://www.twan.com


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