“We cannot trust” Intel and Via’s chip-based crypto, FreeBSD developers say: Developers of the FreeBSD operating system will no longer allow users to trust processors manufactured by Intel and Via Technologies as the sole source of random numbers needed to generate cryptographic keys that can’t easily be cracked by government spies and other adversaries.
The change, which will be effective in the upcoming FreeBSD version 10.0, comes three months after secret documents leaked by former National Security Agency (NSA) subcontractor Edward Snowden said the US spy agency was able to decode vast swaths of the Internet’s encrypted traffic. Among other ways, The New York Times, Pro Publica, and The Guardian reported in September, the NSA and its British counterpart defeat encryption technologies by working with chipmakers to insert backdoors, or cryptographic weaknesses, in their products.
The revelations are having a direct effect on the way FreeBSD will use hardware-based random number generators to seed the data used to ensure cryptographic systems can’t be easily broken by adversaries. Specifically, “RDRAND” and “Padlock”—RNGs provided by Intel and Via respectively—will no longer be the sources FreeBSD uses to directly feed random numbers into the /dev/random engine used to generate random data in Unix-based operating systems. Instead, it will be possible to use the pseudo random output of RDRAND and Padlock to seed /dev/random only after it has passed through a separate RNG algorithm known as “Yarrow.” Yarrow, in turn, will add further entropy to the data to ensure intentional backdoors, or unpatched weaknesses, in the hardware generators can’t be used by adversaries to predict their output.
“For 10, we are going to backtrack and remove RDRAND and Padlock backends and feed them into Yarrow instead of delivering their output directly to /dev/random,” FreeBSD developers said. “It will still be possible to access hardware random number generators, that is, RDRAND, Padlock etc., directly by inline assembly or by using OpenSSL from userland, if required, but we cannot trust them any more.”