Trait Cipher 

pub trait Cipher<'c> {
    const BLOCK_SIZE: usize = 16usize;
    const REQUIRES_PADDING: bool = false;

    // Required methods
    fn key(&self) -> &[u8];
    fn iv(&self) -> &[u8];
    fn set_mode(&self, p: Aes);

    // Provided methods
    fn key_size(&self) -> KeySize { ... }
    fn datatype(&self) -> u8 { ... }
    fn prepare_key(&self, _p: Aes, _dir: Direction) { ... }
    fn init_phase_blocking<T: Instance, M: Mode>(
        &self,
        _p: Aes,
        _aes: &Aes<'_, T, M>,
    ) { ... }
    async fn init_phase<T: Instance>(
        &self,
        _p: Aes,
        _aes: &mut Aes<'_, T, Async>,
    ) { ... }
    fn pre_final(
        &self,
        _p: Aes,
        _dir: Direction,
        _padding_len: usize,
    ) -> [u32; 4] { ... }
    fn post_final_blocking<T: Instance, M: Mode>(
        &self,
        _p: Aes,
        _aes: &Aes<'_, T, M>,
        _dir: Direction,
        _int_data: &mut [u8; 16],
        _temp1: [u32; 4],
        _padding_mask: [u8; 16],
    ) { ... }
    async fn post_final<T: Instance>(
        &self,
        _p: Aes,
        _aes: &mut Aes<'_, T, Async>,
        _dir: Direction,
        _int_data: &mut [u8; 16],
        _temp1: [u32; 4],
        _padding_mask: [u8; 16],
    ) { ... }
    fn get_header_block(&self) -> &[u8] { ... }
    fn uses_gcm_phases(&self) -> bool { ... }
    fn is_ccm_mode(&self) -> bool { ... }
    fn ccm_b0(&self) -> Option<&[u8; 16]> { ... }
    fn ccm_format_aad_header(&self, aad_len: usize) -> ([u8; 10], usize) { ... }
}

This trait encapsulates all cipher-specific behavior.

Provided Associated Constants

const BLOCK_SIZE: usize = 16usize

Processing block size (always 16 bytes for AES).

const REQUIRES_PADDING: bool = false

Indicates whether the cipher requires the application to provide padding.

Required Methods

fn key(&self) -> &[u8]

Returns the symmetric key.

fn iv(&self) -> &[u8]

Returns the initialization vector.

fn set_mode(&self, p: Aes)

Sets the cipher mode (CHMOD field).

Provided Methods

fn key_size(&self) -> KeySize

Returns the key size.

fn datatype(&self) -> u8

Returns the data type setting for this cipher mode.

• 0 = NO_SWAP (32-bit words, no swapping) - Default for all modes

Note: The ST HAL uses different DATATYPE values (BYTE_SWAP for CBC, BIT_SWAP for CTR) with pre-swapped test vectors. This driver uses NO_SWAP consistently with big-endian byte conversion (from_be_bytes/to_be_bytes) for direct NIST test vector compatibility.

fn prepare_key(&self, _p: Aes, _dir: Direction)

Performs any key preparation within the processor, if necessary.

fn init_phase_blocking<T: Instance, M: Mode>( &self, _p: Aes, _aes: &Aes<'_, T, M>, )

Performs any cipher-specific initialization.

async fn init_phase<T: Instance>(&self, _p: Aes, _aes: &mut Aes<'_, T, Async>)

Performs any cipher-specific initialization (async).

fn pre_final(&self, _p: Aes, _dir: Direction, _padding_len: usize) -> [u32; 4]

Called prior to processing the last data block for cipher-specific operations.

fn post_final_blocking<T: Instance, M: Mode>( &self, _p: Aes, _aes: &Aes<'_, T, M>, _dir: Direction, _int_data: &mut [u8; 16], _temp1: [u32; 4], _padding_mask: [u8; 16], )

Called after processing the last data block for cipher-specific operations.

async fn post_final<T: Instance>( &self, _p: Aes, _aes: &mut Aes<'_, T, Async>, _dir: Direction, _int_data: &mut [u8; 16], _temp1: [u32; 4], _padding_mask: [u8; 16], )

Called after processing the last data block for cipher-specific operations (async).

fn get_header_block(&self) -> &[u8]

Returns the AAD header block as required by the cipher (for authenticated modes).

fn uses_gcm_phases(&self) -> bool

Indicates whether this cipher mode uses GCM/CCM phases (init, header, payload, final).

fn is_ccm_mode(&self) -> bool

Indicates whether this is CCM mode (which has different final phase handling). CCM doesn’t use a length block in the final phase, unlike GCM.

fn ccm_b0(&self) -> Option<&[u8; 16]>

Returns the pre-computed B0 block for CCM mode (None for other modes).

fn ccm_format_aad_header(&self, aad_len: usize) -> ([u8; 10], usize)

Returns the formatted AAD length prefix for CCM mode. CCM requires AAD to be prefixed with its length encoding.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<'c, const KEY_SIZE: usize> Cipher<'c> for AesCbc<'c, KEY_SIZE>

const REQUIRES_PADDING: bool = true

impl<'c, const KEY_SIZE: usize> Cipher<'c> for AesCtr<'c, KEY_SIZE>

const REQUIRES_PADDING: bool = false

impl<'c, const KEY_SIZE: usize> Cipher<'c> for AesEcb<'c, KEY_SIZE>

const REQUIRES_PADDING: bool = true

impl<'c, const KEY_SIZE: usize> Cipher<'c> for AesGcm<'c, KEY_SIZE>

const REQUIRES_PADDING: bool = false

impl<'c, const KEY_SIZE: usize> Cipher<'c> for AesGmac<'c, KEY_SIZE>

const REQUIRES_PADDING: bool = false

impl<'c, const KEY_SIZE: usize, const IV_SIZE: usize, const TAG_SIZE: usize> Cipher<'c> for AesCcm<'c, KEY_SIZE, IV_SIZE, TAG_SIZE>

const REQUIRES_PADDING: bool = false