Feeds

Torvalds shoots down call to yank 'backdoored' Intel RdRand in Linux crypto

'We actually know what we are doing. You don't' says kernel boss

Choosing a cloud hosting partner with confidence

Linux supremo Linus Torvalds has snubbed a petition calling for his open-source kernel to spurn the Intel processor instruction RdRand - used for generating random numbers and feared to be nobbled by US spooks to produce cryptographically weak values.

Torvalds branded Kyle Condon, the England-based bloke who created the petition, “ignorant”. The head Penguista said anyone who backed the call to remove RdRand from his operating-system kernel should learn how crypto works.

The fiery Finn wrote at the bottom of Condon’s call to action on Change.org: “Where do I start a petition to raise the IQ and kernel knowledge of people? Guys, go read drivers/char/random.c. Then, learn about cryptography. Finally, come back here and admit to the world that you were wrong.

“Short answer: we actually know what we are doing. You don't.”

Torvalds argued in his mild outburst that the values from RdRand are combined with other sources of randomness, which would thwart any attempts to game the processor's output - but it's claimed that mix is trivial (involving just an exclusive OR) and can be circumvented by g-men.

Posted on 9 September, the petition drew just five signatures and now features a message reading "petition closed". Condon ignited Torvalds’ ire by demanding the following: “Please remove RdRand from /dev/random, to improve the overall security of the Linux kernel.”

The catalyst for the petition seems to be the belief that the RdRand instruction in Intel processors was compromised by the NSA and GCHQ, following the latest disclosures from whistleblower Edward Snowden.

The pseudo-device /dev/random generates a virtually endless stream of random numbers on GNU/Linux systems, which are crucial for encrypting information in a secure manner. RdRand is an instruction [PDF] found in modern Intel chips that stashes a "high-quality, high-performance entropy" generated random number in a given CPU register. These, hopefully, unpredictable values are vital in producing secure session keys, new public-private keys and padding in modern encryption technology. It's feared that spooks within the US intelligence agencies have managed to persuade Intel to hobble that instruction or otherwise ensure its output produces values that weaken the strength of encryption algorithms relying on that random data.

According to the latest clutch of Snowden documents published by ProPublica, The New York Times and The Guardian last week, the NSA and GCHQ have broken basic encryption on the web - mostly by cheating rather than defeating the mathematics involved: unnamed chipsets are believed to have been compromised at the design stage so that encrypted data generated on those systems is easier to crack by spooks armed with supercomputers.

The details are short, but the implication is that American and British spies can crack TLS/SSL connections used to secure HTTPS websites and virtual private networks (VPNs), allowing them to harvest sensitive data such as trade secrets, passwords, banking details, medical records, emails, web searches, internet chats and phone calls, and much more.

Given RdRand is present in quite a few PCs and servers powering or using chunks of the internet, conspiracy theorists are terrified that RdRand is compromised. Given Linux on Intel also run large parts of the internet and systems talking to each other online, the reasoning seems to be traffic running on Linux boxes can also be seen by spooks thanks to RdRand. QED: it should be disabled in Linux.

However, as Torvalds pointed out in response to the petition RdRand is one of many inputs used by the Linux kernel’s pool to generate random characters.

The kernel chieftain wrote: “We use rdrand as _one_ of many inputs into the random pool, and we use it as a way to _improve_ that random pool. So even if rdrand were to be back-doored by the NSA, our use of rdrand actually improves the quality of the random numbers you get from /dev/random. Really short answer: you're ignorant.”

Random-number generation for the kernel space were implemented in 1994 by Theodore Ts'o using secure hashes instead of ciphers. As Tso wrote here following the latest selectively released information by journalists allied to Snowden:

I am so glad I resisted pressure from Intel engineers to let /dev/random rely only on the RDRAND instruction... Relying solely on the hardware random number generator which is using an implementation sealed inside a chip which is impossible to audit is a BAD idea.

®

Internet Security Threat Report 2014

More from The Register

next story
FYI: OS X Yosemite's Spotlight tells Apple EVERYTHING you're looking for
It's on by default – didn't you read the small print?
Russian hackers exploit 'Sandworm' bug 'to spy on NATO, EU PCs'
Fix imminent from Microsoft for Vista, Server 2008, other stuff
Edward who? GCHQ boss dodges Snowden topic during last speech
UK spies would rather 'walk' than do 'mass surveillance'
Microsoft pulls another dodgy patch
Redmond makes a hash of hashing add-on
NOT OK GOOGLE: Android images can conceal code
It's been fixed, but hordes won't have applied the upgrade
'LulzSec leader Aush0k' found to be naughty boy not worthy of jail
15 months home detention leaves egg on feds' faces as they grab for more power
China is ALREADY spying on Apple iCloud users, claims watchdog
Attack harvests users' info at iPhone 6 launch
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Why and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
Three 1TB solid state scorchers up for grabs
Big SSDs can be expensive but think big and think free because you could be the lucky winner of one of three 1TB Samsung SSD 840 EVO drives that we’re giving away worth over £300 apiece.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.