More Side-Channel Attacks

Side channel attacks have always been there, but with Spectre and Meltdown we reached a new level of complexity, danger and pervasiveness. Somehow one of the main ingredients of this family of attacks is to measure the time (or time difference) it takes to process/compute some data and from this to infer information about the data itself. In the 3 years since the announcement of Spectre and Meltdown, a lot of research has been done on this area to find more hardware components suitable to time measurements which can be exploited, to improve the efficiency of the attacks (for which Machine Learning is of great help), and to understand if this type of attacks can become a real everyday threat for everyone. There are recent results in all directions: “Lord of the Ring(s): Side Channel Attacks on the CPU On-Chip Ring Interconnect Are Practical” exploits the contention on the CPU ring interconnect (see here and here for details and the research paper), whereas Google Security made further progress in implementing Spectre against the Chrome Browser using Javascript (here the blog announcement) and other researchers have discovered a way of performing a side channel attack in a Web Browser with Javascript completely disabled (see here and here for details and the research paper) which can be used as an alternative way of to tracking users online. In particular the latter result is worrisome: it seems that the possibility of being subject to this kind of attacks in everyday life, that is browsing in internet on websites, is getting closer.

Side Channel Cryptanalysis

In line with the previous post, it is of interest, albeit only at the research level and we should not really worry about it right now, the paper published by Adi Shamir, Daniel Genkin and Eran Tromer (download here and here for a comment) in which they describe how they have been able to extract an RSA private key managed by GnuPG 1.4.x  (current version is 2.x) by listening to the noises of the PC.

Yes, an acoustic attack on cryptographic private keys seems very unlikely, even if the idea has been discussed for long time. It is very interesting that it has been shown possible in practice, and this means that also other side channel attacks, like listening on the power cord, should be considered seriously at least when your security requirements are really high.