Struct MutationChain 

pub struct MutationChain { /* private fields */ }

HYDRA mutation chain — each token mutation ratchets a SHA3-256 hash chain. This provides Post-Compromise Security (PCS): a stolen token becomes invalid once the legitimate holder advances the chain.

Implementations

impl MutationChain

pub fn new(seed: [u8; 32]) -> Self

Initialise from a random 32-byte seed (should be CSPRNG output).

pub fn from_state(state: [u8; 32], counter: u64) -> Self

Restore from persisted state.

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

Advance the chain once and return the new epoch tag. The new state is SHA3-256(old_state || counter_bytes).

pub fn current_counter(&self) -> u64

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

pub fn check_token_counter(&self, token_ctr: u64) -> QVResult<()>

Verify a token’s mutation counter is strictly greater than the stored chain counter. Enforces monotonicity — replay of any previous token is immediately rejected.