TrueCrypt uses Hardware AES that Intel says I don't have?

[frontier204]

Hi all,

I've run into a "smile and nod" moment trying to encrypt my laptop...
Any ideas why TrueCrypt on my laptop with Core i5 2410m seems to be working with some sort of hardware acceleration even when Intel says that CPU has no AES-NI? (See Intel® Core)

This was backed up both by the benchmark, which reports >1GB/s AES speeds and the way the full encryption process + wipe on my Seagate Momentus XT 320GB saturates the drive but doesn't even put 10% load on the CPU. By comparison, my desktop's Core i5 2500k (which definitely has AES-NI) reports >2GB/s AES speed, which is an effect of more cores / cache / clocks.

Do the mobile Sandy Bridges have some other AES accel or partially-enabled AES-NI?
I can't see any other explanation other than the stat sheet is happily wrong, given that TrueCrypt doesn't seem to support other hardware encryption methods:
TrueCrypt - Free Open-Source Disk Encryption - Documentation - Hardware Acceleration

As a secondary question, would this mean I can try out an soft-encrypted SSD on my laptop without worrying about being CPU bound?

[Trevayne10]

Hi, Frontier204 -

Hello from Montgomery Village MD (USA) here -

The answer is: We lucked out!

The intel core i5-2410M CPU in your Asus laptop indeed has AES-NI implemented in hardware. The key is: the coding of your OEM BIOS. Apparently Asus wrote your laptop's BIOS with AES-NI fully enabled. You're one of the lucky few.

I have an early i5-2410M CPU-based Toshiba laptop (Satellite L755-S5258), and I lucked out, as well. My BIOS was written to recognize my laptop's AES-NI hardware.

When I run TruCrypt, it shows 1.3 GBs, throughput (50 MB), which is clearly a hardware encryption metric. In other words, AES-NI is running at full bore in the CPU hardware.

Intel burned the full AES-NI encryption instruction set right onto the i5-2410M die, but left it up to all the various notebook/laptop OEM's whether to enable it or not. Obviously Asus & Toshiba chose to.

Go to this link, and read the very last line of fine print at the bottom of the website:

http://ark.intel.com/products/52224/...up-to-2_90-GHz)

"Some products can support AES New Instructions with a Processor Configuration update, in particular, i7-2630QM/i7-2635QM, i7-2670QM/i7-2675QM, i5-2430M/i5-2435M, i5-2410M/i5-2415M. Please contact OEM for the BIOS that includes the latest Processor configuration update."

Enjoy!

-Trev