Struct HkdfSha256 

pub struct HkdfSha256 { /* private fields */ }

HKDF-SHA-256 (RFC 5869).

Built on HmacSha256, so it is served by whichever driver is registered for it; see driver.

Example

let hk = HkdfSha256::new(b"salt", b"input key material");
let mut okm = [0u8; 42];
hk.expand(b"context", &mut okm)?;

// Or keep the pseudorandom key to expand later:
let (prk, _) = HkdfSha256::extract(b"salt", b"input key material");
HkdfSha256::from_prk(&prk)?.expand(b"context", &mut okm)?;

Implementations

impl HkdfSha256

pub const PRK_SIZE: usize = HmacSha256::OUTPUT_SIZE

Size of the pseudorandom key, in bytes.

pub const MAX_OUTPUT_SIZE: usize

Largest output expand can produce, in bytes.

pub fn new(salt: &[u8], ikm: &[u8]) -> Self

Extract a pseudorandom key from ikm with salt.

An empty salt is equivalent to the RFC’s default of PRK_SIZE zeros.

pub fn extract(salt: &[u8], ikm: &[u8]) -> ([u8; 32], Self)

Like new, also returning the pseudorandom key.

pub fn from_prk(prk: &[u8]) -> Result<Self, Error>

Skip the extract step, using prk as the pseudorandom key.

Returns Error::InvalidKey if prk is shorter than PRK_SIZE.

pub fn expand(&self, info: &[u8], okm: &mut [u8]) -> Result<(), Error>

Fill okm with output keying material bound to info.

Returns Error::InvalidInput if okm is longer than MAX_OUTPUT_SIZE.

Trait Implementations

impl Clone for HkdfSha256

fn clone(&self) -> HkdfSha256

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for HkdfSha256

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

Formats the value using the given formatter.