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Because the time that the Extended Euclidean algorithm depends on the inputs (and, in particular, is a complex function of the two, depending on the ratio expressed as a continguous fraction), there may be some leakage there. It occurs to me, however, that there is a very simple countermeasure; assuming that the secret modulus you are inverting is $p$, and ...


4

There are two papers on conventional differential cryptanalysis of SEED. The last one penetrates only half of the cipher. Even though there are few third-party cryptanalysis papers, there is no indication that the cipher is weak. Fault attacks are quite irrelevant in the SSL setting. I would be more concerned with BEAST-like attacks, as SEED is a ...


4

A fault injection attack is based on the fact that you have a healthy black box on which you can do queries, but you can mess with the black box, for example flipping random bits. In real life this could for example be a RFID chip which can be messed with using strong electronic fields. Attacks like these are generally: Very sophisticated in theory and ...


4

How did they jump from the spectrogram showing the RSA exponentiation timings straight to the secret bits? Actually, they're jumping to secret bits; however those aren't the secret bits you're thinking of. The bits displayed above are not the actual bits of $p$ and $q$. Instead, those are the bits from the secret exponent; because GnuPG uses CRT (and ...


2

It all comes down to your threat model, right? Just because an implementation is done in hardware does not mean that power and fault attacks must be considered. If I host the hardware in my secure facility with armed guards at the door, but the hardware is connected to a machine which is connected to the internet, I might feel that it is okay to not be ...


2

Actually, those two algorithms are surprisingly close; I'll write both of them up to show how close they are. They both can be written as a combination of three substeps: A := Add( B, C ) This takes the two points B and C, and adds them together (I'll be writing things in additive notation; in RSA, with would be a modular multiplication) A := Double( B ...


2

I found a reference of a side-channel attack to modular inversion being performed: New Branch Prediction Vulnerabilities in OpenSSL and Necessary Software Countermeasures (Onur Acıic¸mez, Shay Gueron, and Jean-Pierre Seifert) February 7, 2007 The Main Result: Modular Inversion Via Binary Extended Euclidean Algorithm Succumbs to Simple Branch Prediction ...



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