Struct Blake3 

pub struct Blake3;

BLAKE3 single-stage KDF (unofficial KDF id 0xFF01).

BLAKE3 is an extendable-output function, so it is used exactly like Shake256: the key schedule is built from a single Kdf::labeled_derive call whose Derive primitive is the BLAKE3 XOF. The output size is 32 bytes.

Interoperability

BLAKE3 is not registered in the IANA “HPKE KDF Identifiers” registry and is not specified by any HPKE standard. The identifier 0xFF01 is an stdx-private, unofficial value chosen to stay clear of the low IDs IANA is likely to assign to future official KDFs; ciphersuites using this KDF only interoperate with implementations that adopt the same convention.

Example

use hpke::kdf::{Blake3, Kdf};

let suite_id = b"HPKE\x64\x7a\xff\x01\x00\x03";
let mut output_keying_material = [0u8; 32];
Blake3::labeled_derive(&mut output_keying_material, &[b"ikm"], suite_id, b"label", &[b"info"]).unwrap();

Trait Implementations

impl Clone for Blake3

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Blake3

impl Debug for Blake3

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

Formats the value using the given formatter.

impl Eq for Blake3

impl Kdf for Blake3

const HPKE_KDF_ID: u16 = 0xFF01

The HPKE KDF identifier (draft-ietf-hpke-hpke-05 Section 7.2, IANA “HPKE KDF Identifiers”), used to build the ciphersuite suite_id.

const SINGLE_STAGE: bool = true

Whether this is a single-stage KDF (draft-ietf-hpke-hpke-05 Section 4).

type Hash = Blake3

The hash function underlying the default HKDF construction.

fn labeled_derive( out: &mut [u8], input_keying_material: &[&[u8]], suite_id: &[u8], label: &[u8], context: &[&[u8]], ) -> Result<(), HpkeError>

draft-ietf-hpke-hpke-05 Section 4.4 LabeledDerive(input_keying_material, label, context, L): Derive(input_keying_material || "HPKE-v1" || suite_id || I2OSP(len(label), 2) || label || I2OSP(L, 2) || context, L), where L == out.len() and the elements of input_keying_material and context are absorbed in order.

const OUTPUT_SIZE: usize = <Self::Hash as crypto::Hasher>::OUTPUT_SIZE

Output size of the extract step (the hash output size).

fn labeled_extract( salt: &[u8], suite_id: &[u8], label: &[u8], input_keying_material: &[u8], ) -> Hash

draft-ietf-hpke-hpke-05 Section 4.4 LabeledExtract(salt, label, input_keying_material): Extract(salt, "HPKE-v1" || suite_id || label || input_keying_material).

fn labeled_expand( out: &mut [u8], pseudorandom_key: &[u8], suite_id: &[u8], label: &[u8], info: &[u8], ) -> Result<(), HpkeError>

draft-ietf-hpke-hpke-05 Section 4.4 LabeledExpand(pseudorandom_key, label, info, L): Expand(pseudorandom_key, I2OSP(L, 2) || "HPKE-v1" || suite_id || label || info, L), where L == out.len(). The info string is absorbed incrementally, so it may be arbitrarily long.

impl PartialEq for Blake3

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Blake3