Hardware Acceleration
Some processors (CPUs) support hardware-accelerated
AES encryption,* which is typically 4-8 times faster than encryption performed by the purely software implementation on the same processors.
By default, TrueCrypt uses hardware-accelerated AES on computers that have a processor where the Intel AES-NI instructions are available. Specifically, TrueCrypt uses the AES-NI instructions that perform so-called AES rounds (i.e. the main portions of the AES algorithm).** TrueCrypt does not use any of the AES-NI instructions that perform key generation.
To find out whether TrueCrypt can use hardware-accelerated AES on your computer, select
Settings >
Performance and check the field labeled '
Processor (CPU) in this computer provides hardware acceleration for AES'.
To find out whether a processor you want to purchase supports the Intel AES-NI instructions (also called "AES New Instructions"), which TrueCrypt uses for hardware-accelerated AES, please check the documentation for the processor or contact the vendor/manufacturer.
The following are examples of desktop processors where TrueCrypt should be able to use hardware-accelerated AES. Note: This list is
not exhaustive. There are many other processors that support hardware-accelerated AES. (Last updated July 19, 2010)
- Intel Core i7-980X
- Intel Core i7-970
- Intel Core i5-650
- Intel Core i5-655K
- Intel Core i5-660
- Intel Core i5-661
- Intel Core i5-670
- Intel Core i5-680
The following are examples of mobile-device processors where TrueCrypt should be able to use hardware-accelerated AES. Note: This list is
not exhaustive. (Last updated July 19, 2010)
- Intel Core i7-620LM
- Intel Core i7-620M
- Intel Core i7-620UM
- Intel Core i7-640LM
- Intel Core i7-640UM
- Intel Core i7-660UM
- Intel Core i5-520E
- Intel Core i5-520M
- Intel Core i5-520UM
- Intel Core i5-540M
- Intel Core i5-540UM
- Intel Core i7-610E
If you want to disable hardware acceleration of AES (e.g. because you want TrueCrypt to use only a fully open-source implementation of AES), you can do so by selecting
Settings >
Performance and disabling the option '
Accelerate AES encryption/decryption by using the AES instructions of the processor'. Note that when this setting is changed, the operating system needs to be restarted to ensure that all TrueCrypt components internally perform the requested change of mode. Also note that when you create a TrueCrypt Rescue Disk, the state of this option is written to the Rescue Disk and used whenever you boot from it (affecting the pre-boot and initial boot phase). To create a new TrueCrypt Rescue Disk, select
System >
Create Rescue Disk.
Note: Support for hardware acceleration was introduced in TrueCrypt 7.0.
