Struct DerivableSecret

pub struct DerivableSecret {
    pub(crate) level: usize,
    pub(crate) kdf: Hkdf<Sha512>,
}

A secret that can have child-subkey derived from it.

Fields

level: usize

Derivation level, root = 0, every child_key increments it

kdf: Hkdf<Sha512>

An instance of the HKDF (Hash-based Key Derivation Function) with SHA-512 as the underlying hash function. It is used to derive child keys.

Implementations

impl DerivableSecret

pub fn new_root(root_key: &[u8], salt: &[u8]) -> Self

Derive root secret key from a secret material and salt.

The salt is just additional data t used as an additional input to the HKDF.

pub fn level(&self) -> usize

Get derivation level

This is useful for ensuring a correct derivation level is used, in various places.

Root keys start at 0, and every derived key increments it.

pub fn child_key(&self, cid: ChildId) -> DerivableSecret

pub fn federation_key(&self, federation_id: &FederationId) -> DerivableSecret

Derive a federation-ID-based child key from self.

This is useful to ensure that the same root secret is not reused across multiple fedimint-client instances for different federations.

We reset the level to 0 here since fedimint-client expects its root secret to be at that level.

pub fn to_secp_key<C: Signing>(self, ctx: &Secp256k1<C>) -> Keypair

secp256k1 keys are used for bitcoin deposit addresses, redeem keys and contract keys for lightning.

pub fn to_bls12_381_key(&self) -> Scalar

bls12-381 keys are used for the guardians’ threshold signature scheme, and most importantly for its use for the blinding keys for e-cash notes.

pub fn to_chacha20_poly1305_key_raw(&self) -> [u8; 32]

pub fn to_chacha20_poly1305_key(&self) -> UnboundKey

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

Generate a pseudo-random byte array from the derivable secret.

Trait Implementations

impl Clone for DerivableSecret

fn clone(&self) -> DerivableSecret

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for DerivableSecret

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

Formats the value using the given formatter.