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, VeraCrypt uses hardware-accelerated AES on computers that have a processor where the Intel AES-NI instructions are available. Specifically, VeraCrypt uses the AES-NI instructions that perform so-called AES rounds (i.e. the main portions of the AES + algorithm).** VeraCrypt does not use any of the AES-NI instructions that perform key generation.

+Note: By default, VeraCrypt uses hardware-accelerated AES also when an encrypted Windows system is booting or resuming from hibernation (provided that the processor supports the Intel AES-NI instructions).

+To find out whether VeraCrypt can use hardware-accelerated AES on your computer, select +Settings > Performance/Driver Configuration and check the field labeled 'Processor (CPU) in this computer supports 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 VeraCrypt uses for hardware-accelerated AES, please check the documentation for the processor or contact the vendor/manufacturer. + Alternatively, click +here to view an official list of Intel processors that support the AES-NI instructions. However, note that some Intel processors, which the Intel website lists as AES-NI-supporting, actually support the AES-NI instructions only with a Processor Configuration + update (for example, i7-2630/2635QM, i7-2670/2675QM, i5-2430/2435M, i5-2410/2415M). In such cases, you should contact the manufacturer of the motherboard/computer for a BIOS update that includes the latest Processor Configuration update for the processor.

+If you want to disable hardware acceleration of AES (e.g. because you want VeraCrypt to use only a fully open-source implementation of AES), you can do so by selecting Settings > +Performance and Driver Options 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 VeraCrypt components internally perform the requested change of mode. Also note that when you create a VeraCrypt 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 VeraCrypt Rescue Disk, select +System > Create Rescue Disk.

* In this chapter, the word 'encryption' also refers to decryption.
+** Those instructions are +AESENC, AESENCLAST, +AESDEC, and AESDECLAST and they perform the following AES transformations: +ShiftRows, SubBytes, +MixColumns, InvShiftRows, +InvSubBytes, InvMixColumns, and +AddRoundKey (for more details about these transformations, see [3]).