Selective encryption to boost instant-on memory

Non-volatile main memory in computers could become a secure reality thanks to new encryption techniques, according to scientists at North Carolina State University.

Non-volatile memory, such as phase-change memory, has been touted as a replacement for conventional dynamic random access memory (DRAM) as the main memory of computers because it allows instant start-up and squeezes more memory into less space.

But the technology has been held back by security fears over what information is left on the chip after the machine is switched off, with potentially sensitive information staying available.

We could use hardware to encrypt everything, but then the system would run very slowly – because it would constantly be encrypting and decrypting data

According to the researchers, this feature could give criminals access to personal data if a laptop or smartphone were stolen and because the data is stored in main memory, it cannot be encrypted using software.

Software cannot manage main memory functions, because software itself operates in main memory.

Instead, the NC State researchers have developed a system of hardware encryption system called i-NVMM, that selectively chooses which data to keep encrypted.

“We could use hardware to encrypt everything,” said Yan Solihin, associate professor of electrical and computer engineering at NC State. “But then the system would run very slowly – because it would constantly be encrypting and decrypting data.

“Instead, we developed an algorithm to detect data that is likely not needed by the processor. This allows us to keep 78% of main memory encrypted during typical operation, and only slows the system’s performance by 3.7%.”

The researchers claimed the i-NVMM tool had additional benefits, including an algorithm that also detects idleness, which meant data not currently in use – such as your credit card number – is automatically encrypted.

And although 22% of “in-use” data is unecnrypted during computation, it is encrypted when the computer is powered down.

“Basically, unless someone accesses your computer while you’re using it, all of your data is protected,” Solihin says. “We’re now seeking industry partners who are interested in this technology.”