GnuPG crypto library cracked, look for patches

Boffins bust libgcrypt via side-channel


Linux users need to check out their distributions to see if a nasty bug in libgcrypt20 has been patched.

The software fix, which has landed in Debian and Ubuntu, addresses a side-channel attack published last week.

The researchers published their work at the International Association for Cryptologic Research's e-print archive last week. The paper was authored by Daniel Bernstein, Joachim Breitner, Daniel Genkin, Leon Groot Bruinderink, Nadia Heninger, Tanja Lange, Christine van Vredendaal and Yuval Yarom (who hail variously from the Technical University of Eindhoven, the University of Illinois, the University of Pennsylvania, the University of Maryland, and the University of Adelaide).

What they found is that the libgcrypt library used what's called “sliding windows”, a method for carrying out the mathematics of cryptography – but one that's known to leak data.

The researchers looked at the left-to-right sliding window calculation in libgcrypt, in which the sliding window data leak was tolerated because it was believed only part of a key was recoverable (40 percent of bits in a four-bit sliding window; 33 percent in a five-bit sliding window).

What they found was an unpleasant surprise: a complete break of the library's RSA-1024: “We show for the first time that the direction of the encoding matters: the pattern of squarings and multiplications in left-to-right sliding windows leaks significantly more information about the exponent than right-to-left”.

To get at the processing, the researchers also needed to carry out a side-channel attack, specifically a flush+reload cache-timing attack “that monitors the target's cache access patterns”.

Debian users can update the library here; Ubuntu has it here. ®

Similar topics


Other stories you might like

  • The future: Windows streaming through notched Apple screens

    Choice is the word for Jamf's Dean Hager

    Interview As Apple's devices continue to find favour with enterprise users, the fortress that is Windows appears to be under attack in the corporate world.

    Speaking to The Register as the Jamf Nation User Conference wound down, the software firm's CEO, Dean Hager, is - unsurprisingly - ebullient when it comes to the prospects for Apple gear in the world of suits.

    Jamf specialises in device management and authentication, and has long been associated with managing Apple hardware in business and education environments. In recent years it has begun connecting its products with services such as Microsoft's Azure Active Directory as administrators face up to a hybrid working future.

    Continue reading
  • There’s a wave of ransomware coming down the pipeline. What can you do about it?

    AI can help. Here’s how…

    Sponsored The Colonial Pipeline attack earlier this year showed just how devastating a ransomware attack is when it is targeted at critical infrastructure.

    It also illustrated how traditional security techniques are increasingly struggling to keep pace with determined cyber attackers, whether their aim is exfiltrating data, extorting organisations, or simply causing chaos. Or, indeed an unpleasant combination of all three.

    So, what are your options? More people looking for more flaws isn’t going to be enough – there simply aren’t enough skilled people, there are too many bugs, and there are way too many attackers. So, it’s clear that smart cyber defenders need to be supplemented by even smarter technology incorporating AI. You can learn what this looks like by checking out this upcoming Regcast, “Securing Critical Infrastructure from Cyber-attack” on October 28 at 5pm.

    Continue reading
  • Ransomware criminals have feelings too: BlackMatter abuse caused crims to shut down negotiation portal

    Or so says infsec outfit Emsisoft

    Hurling online abuse at ransomware gangs may have contributed to a hardline policy of dumping victims' data online, according to counter-ransomware company Emsisoft.

    Earlier this month, the Conti ransomware gang declared it would publish victims' data and break off ransom negotiations if anyone other than "respected journalist and researcher personalities" [sic] dared publish snippets of ransomware negotiations, amid a general hardening of attitudes among ransomware gangs.

    Typically these conversation snippets make it into the public domain because curious people log into ransomware negotiation portals hosted by the criminals. The BlackMatter (aka DarkSide) gang's portal credentials (detailed in a ransom note) became exposed to the wider world, however, and the resulting wave of furious abuse hurled at the crims prompted them to pull up the virtual drawbridge.

    Continue reading

Biting the hand that feeds IT © 1998–2021