Struct HmacSha256 

pub struct HmacSha256 { /* private fields */ }

Available on (crate features mac-hmac or mac-blake3) and crate feature mac-hmac only.

Streaming HMAC-SHA256 for inputs that don’t fit in memory.

Construct with HmacSha256::new, absorb data with update, finalise with finalize (returns the 32-byte tag) or verify (constant-time compare against an expected tag).

Example

use crypt_io::mac::HmacSha256;

let mut m = HmacSha256::new(b"shared key")?;
m.update(b"first chunk ");
m.update(b"second chunk");
let tag = m.finalize();
assert_eq!(tag.len(), 32);

Implementations

impl HmacSha256

pub fn new(key: &[u8]) -> Result<Self>

Construct a fresh hasher under key.

Errors

Returns Error::Mac if the upstream hmac crate refuses the key. Unreachable in practice (HMAC accepts any key length).

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

Absorb data into the running MAC. Returns &mut Self so calls can chain.

pub fn finalize(self) -> [u8; 32]

Finalise the MAC and return the 32-byte tag. Consumes the hasher.

pub fn verify(self, expected_tag: &[u8]) -> bool

Finalise and verify against expected_tag in constant time. Returns true iff the computed tag matches expected_tag. Consumes the hasher.

Trait Implementations

impl Clone for HmacSha256

fn clone(&self) -> HmacSha256

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for HmacSha256

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.