Struct AesContext

Source

pub struct AesContext { /* private fields */ }

Expand description

An AES work queue user.

Implementations§

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impl AesContext

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pub fn new( cipher_mode: impl Into<CipherState>, operation: Operation, key: impl Into<Key>, ) -> Self

Creates a new context to encrypt or decrypt data with the given block cipher mode of operation.

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pub fn process<'t>( &'t mut self, input: &'t [u8], output: &'t mut [u8], ) -> Result<AesHandle<'t>, Error>

Starts transforming the input buffer, and writes the result into the output buffer.

For encryption the input is the plaintext, the output is the ciphertext.
For decryption the input is the ciphertext, the output is the plaintext.

The returned Handle must be polled until it returns true. Dropping the handle before the operation finishes will cancel the operation.

For an example, see the documentation of AesBackend.

§Errors

Error when the lengths of the input and output buffers do not match.
Error when ECB or OFB cipher modes are used and the data length is not a multiple of the block size (16).

Source

pub fn process_in_place<'t>( &'t mut self, buffer: &'t mut [u8], ) -> Result<AesHandle<'t>, Error>

Starts transforming the buffer.

The processed data is written back to the buffer.

The returned Handle must be polled until it returns true. Dropping the handle before the operation finishes will cancel the operation.

Operates similarly to AesContext::process, but overwrites the data buffer with the result of the transformation.

§Examples

use esp_hal::aes::{AesBackend, AesContext, Operation, cipher_modes::Ecb};
let mut aes = AesBackend::new(peripherals.AES);
// Start the backend, which pins it in place and 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, in place. The ECB mode of operation requires that
// the length of the data is a multiple of the block (16 bytes) size.
let mut buffer: [u8; 16] = *b"message\0\0\0\0\0\0\0\0\0";

let operation_handle = ecb_encrypt.process_in_place(&mut buffer)?;
operation_handle.wait_blocking();

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