Entries Tagged "side-channel attacks"

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Power Analysis of RFID Tags

This is great work by Yossi Oren and Adi Shamir:

Abstract (Summary)

We show the first power analysis attack on passive RFID tags. Compared to standard power analysis attacks, this attack is unique in that it requires no physical contact with the device under attack. While the specific attack described here requires the attacker to actually transmit data to the tag under attack, the power analysis part itself requires only a receive antenna. This means that a variant of this attack can be devised such that the attacker is completely passive while it is acquiring the data, making the attack very hard to detect. As a proof of concept, we describe a password extraction attack on Class 1 Generation 1 EPC tags operating in the UHF frequency range. The attack presented below lets an adversary discover the kill password of such a tag and, then, disable it. The attack can be readily adapted to finding the access and kill passwords of Gen 2 tags. The main significance of our attack is in its implications ­ any cryptographic functionality built into tags needs to be designed to be resistant to power analysis, and achieving this resistance is an undertaking which has an effect both on the price and on the read range of tags.

My guess of the industry’s response: downplay the results and pretend it’s not a problem.

Posted on March 17, 2006 at 12:22 PMView Comments

AES Timing Attack

Nice timing attack against AES.

For those of you who don’t know, timing attacks are an example of side-channel cryptanalysis: cryptanalysis using additional information about the inner workings of the cryptographic algorithm. I wrote about them here.

What’s the big idea here?

There are two ways to look at a cryptographic primitive: block cipher, digital signature function, whatever. The first is as a chunk of math. The second is a physical (or software) implementation of that math.

Traditionally, cryptanalysis has been directed solely against the math. Differential and linear cryptanalysis are good examples of this: high-powered mathematical tools that can be used to break different block ciphers.

On the other hand, timing attacks, power analysis, and fault analysis all makes assumptions about implementation, and uses additional information garnered from attacking those implementations. Failure analysis assumes a one-bit feedback from the implementation—was the message successfully decrypted—in order to break the underlying cryptographic primitive. Timing attacks assumes that an attacker knows how long a particular encryption operation takes.

Posted on May 17, 2005 at 10:05 AMView Comments

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Sidebar photo of Bruce Schneier by Joe MacInnis.