Struct Hkdf

pub struct Hkdf<H: BitcoinHash> {
    pub(crate) prk: Hmac<H>,
}

Implements the RFC5869 hash based key derivation function using the hash function H.

Fields

prk: Hmac<H>

Implementations

impl<H: BitcoinHash> Hkdf<H>

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

Run HKDF-extract and keep the resulting pseudo random key as internal state

Inputs

• ikm: Input keying material, secret key material our keys will be derived from
• salt: Optional salt value, if not required set to &[0; H::LEN]. As noted in the RFC the salt value can also be a secret.

pub fn from_prk(prk: Hmac<H>) -> Self

Construct the HKDF from a pseudo random key that has the correct distribution and length already (e.g. because it’s the output of a previous HKDF round), skipping the HKDF-extract step. If in doubt, please use Hkdf::new instead!

See also Hkdf::derive_hmac.

pub fn derive<const LEN: usize>(&self, info: &[u8]) -> [u8; LEN]

Run HKDF-expand to generate new key material

Inputs

• info: Defines which key to derive. Different values lead to different keys.
• LEN: Defines the length of the key material to generate in octets. Note that LEN <= H::LEN * 255 has to be true.

Panics

If LEN > H::LEN * 255.

pub fn derive_hmac(&self, info: &[u8]) -> Hmac<H>

Run HKDF-expand to generate new key material with L = H::LEN

See Hkdf::derive for more information.

Trait Implementations

impl<H: Clone + BitcoinHash> Clone for Hkdf<H>

fn clone(&self) -> Hkdf<H>

Returns a copy of the value.

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

Performs copy-assignment from source.