Top secret: PGP secures Linux

The move is part of the NSA's Security-Enhanced Linux programme (SELinux), which aims to radically up the security levels possible from open source operating systems.

The contract, worth $1.2m over two years, will see a division of PGP work with the NSA and will use its knowledge of the security controls of the Linux kernel - the core of the operating system. PGP said all security improvements to Linux developed under the deal will be fed back to the open source community.

The NSA is part of the US government and recently won a "lifetime menace" award from privacy group Privacy International for snooping on citizens' communications. PGP, now a division of security giant Network Associates, was a security standard originally written by cryptographer Philip Zimmerman to help civil and human rights campaigners communicate in safety.