Struct StreamingHashHmac 

pub struct StreamingHashHmac<H, F>
where
    H: StreamingHash,
    F: Fn() -> H + Send,
{ /* private fields */ }

Generic HMAC over any StreamingHash implementation.

The type parameter H is the underlying hash; F is the factory that creates fresh instances of H. Both H and F must be Send to allow the MAC to cross thread boundaries.

Construction

Use StreamingHashHmac::new to provide a key, block size, and hash factory. The resulting value implements one-shot StreamingHashHmac::mac_oneshot and incremental StreamingHashHmac::streaming_session.

Example

use oxicrypto_hash::Sha256Streaming;
use oxicrypto_mac::hmac_streaming_hash::StreamingHashHmac;

let key = b"secret-key-for-hmac";
let msg = b"hello, world";
let mut tag = [0u8; 32];
let mut hmac = StreamingHashHmac::new(key, 64, || Sha256Streaming::new())?;
hmac.mac_oneshot(msg, &mut tag)?;

Implementations

impl<H, F> StreamingHashHmac<H, F>

where H: StreamingHash, F: Fn() -> H + Send,

pub fn new( key: &[u8], block_size: usize, output_len: usize, factory: F, ) -> Result<Self, CryptoError>

Construct an HMAC instance with the given key, hash block_size, and output_len of the underlying H.

• If key.len() > block_size the key is pre-hashed using a fresh hasher from factory.
• The padded key is zero-extended to exactly block_size bytes.

Errors

Returns CryptoError::BadInput when block_size or output_len is zero, or when key pre-hashing would write into a zero-length buffer.

pub fn mac_oneshot(&self, msg: &[u8], out: &mut [u8]) -> Result<(), CryptoError>

Compute a one-shot HMAC tag over msg, writing into out.

out.len() must be at least self.output_len().

Errors

• CryptoError::BufferTooSmall if out.len() < output_len.

pub fn output_len(&self) -> usize

The hash output length in bytes.

pub fn block_size(&self) -> usize

The hash block size in bytes.

pub fn verify(&self, msg: &[u8], expected: &[u8]) -> Result<(), CryptoError>

Constant-time verification: compute the HMAC and compare to expected.

Returns Ok(()) if they match, CryptoError::InvalidTag otherwise.

pub fn streaming_session(&self) -> StreamingHashHmacSession<H, F>

where F: Clone,

Create an incremental streaming HMAC session.

Returns a StreamingHashHmacSession that accepts data via update() and produces the final tag via finalize().