esp_hal::aes::dma

Struct AesDmaBackend

pub struct AesDmaBackend<'d> { /* private fields */ }

Expand description

DMA-enabled AES processing backend.

The backend will try its best to use hardware acceleration as much as possible. It will fall back to CPU-driven processing (equivalent to AesBackend) in some cases, including:

When the block cipher is not implemented in hardware.
When the data is not correctly aligned to the needs of the hardware (e.g. when using a stream cipher mode, the data length is not an integer multiple of 16 bytes).

§Example

use esp_hal::aes::{AesContext, Operation, cipher_modes::Ecb, dma::AesDmaBackend};
let dma_channel = peripherals.DMA_CH0;
let mut aes = AesDmaBackend::new(peripherals.AES, dma_channel);
// Start the backend, which allows processing AES operations.
let _backend = aes.start();

// Create a new context with a 128-bit key. The context will use the ECB block cipher mode.
// The key length must be supported by the hardware.
let mut ecb_encrypt = AesContext::new(Ecb, Operation::Encrypt, *b"SUp4SeCp@sSw0rd\0");

// Process a block of data in this context. The ECB mode of operation requires that
// the length of the data is a multiple of the block (16 bytes) size.
let input_buffer: [u8; 16] = *b"message\0\0\0\0\0\0\0\0\0";
let mut output_buffer: [u8; 16] = [0; 16];

let operation_handle = ecb_encrypt
    .process(&input_buffer, &mut output_buffer)
    .unwrap();
operation_handle.wait_blocking();

// output_buffer now contains the ciphertext
assert_eq!(
    output_buffer,
    [
        0xb3, 0xc8, 0xd2, 0x3b, 0xa7, 0x36, 0x5f, 0x18, 0x61, 0x70, 0x0, 0x3e, 0xd9, 0x3a,
        0x31, 0x96,
    ]
);

Implementations§

Source §

impl<'d> AesDmaBackend<'d>

Source

pub fn new(aes: AES<'d>, dma: impl DmaChannelFor<AES<'d>>) -> Self

Creates a new DMA-enabled AES backend.

The backend needs to be started before it can execute AES operations.

§Example

use esp_hal::aes::dma::AesDmaBackend;

let dma_channel = peripherals.DMA_CH0;
let mut aes = AesDmaBackend::new(peripherals.AES, dma_channel);

Source

pub fn start(&mut self) -> AesDmaWorkQueueDriver<'_, 'd>

Registers the DMA-driven AES driver to process AES operations.

The driver stops operating when the returned object is dropped.

§Example

use esp_hal::aes::dma::AesDmaBackend;

let dma_channel = peripherals.DMA_CH0;
let mut aes = AesDmaBackend::new(peripherals.AES, dma_channel);
let _handle = aes.start();