Struct MacCtx 

pub struct MacCtx { /* private fields */ }

Stateful MAC context (EVP_MAC_CTX*).

!Clone — use fork() to duplicate mid-stream state. All stateful operations require &mut self.

Implementations

impl MacCtx

pub fn new(alg: &MacAlg) -> Result<Self, ErrorStack>

Create a new (uninitialised) MAC context from an algorithm descriptor.

Call MacCtx::init with a key before feeding data.

Errors

pub fn init( &mut self, key: &[u8], params: Option<&Params<'_>>, ) -> Result<(), ErrorStack>

Initialise (or re-initialise) with a key and optional parameters.

key is always copied into the MAC context by EVP_MAC_init. HMAC additionally pads the key into IPAD/OPAD. The copy is unavoidable.

Errors

pub fn update(&mut self, data: &[u8]) -> Result<(), ErrorStack>

Feed data into the ongoing MAC computation.

Errors

pub fn finish(&mut self, out: &mut [u8]) -> Result<usize, ErrorStack>

Finalise the MAC and write into out.

out must be at least self.mac_size() bytes. Returns the number of bytes written.

Errors

pub fn finish_xof(&mut self, out: &mut [u8]) -> Result<(), ErrorStack>

Finalise with variable-length XOF output (KMAC-128, KMAC-256).

Errors

pub fn mac_size(&self) -> usize

Expected MAC output length in bytes. Available after init.

pub fn block_size(&self) -> usize

Block size of the underlying MAC algorithm in bytes.

For HMAC, this is the block size of the underlying hash (e.g. 64 for SHA-256, 128 for SHA-384/SHA-512). Required by protocols that derive IPAD/OPAD or align buffers to the hash block size.

Returns 0 before MacCtx::init is called.

pub fn alg(&self) -> Option<MacAlg>

Return the algorithm descriptor associated with this context.

Bumps the algorithm’s reference count so the returned MacAlg is independently owned and may outlive the context.

Returns None if no algorithm is associated (e.g. context was just allocated but not yet bound to an algorithm).

pub fn fork(&self) -> Result<MacCtx, ErrorStack>

Fork the current mid-stream state into a new context (EVP_MAC_CTX_dup).

Named fork (not clone) to signal this is a potentially expensive deep copy.

Errors

Trait Implementations

impl Drop for MacCtx

fn drop(&mut self)

Executes the destructor for this type.

impl Send for MacCtx