Struct StateKey 

pub struct StateKey(/* private fields */);

The key a server seals requestState under.

Thirty-two bytes, the HMAC-SHA256 block-size recommendation’s lower bound, supplied by the caller rather than generated here: this layer may not draw from a random source itself. The transports fill one from the OS CSPRNG when the server was built without one.

Implementations

impl StateKey

pub const fn from_bytes(bytes: [u8; 32]) -> Self

A key from raw bytes.

For a deployment running several replicas behind one endpoint, every replica must be given the same key, or a retry routed to a different replica will find its state refused as tampered.

pub fn seal(&self, state: &str) -> Option<String>

Seals state so that any change to it is detectable.

The format is <hex mac>.<state>: the MAC is fixed-width, so the first . always ends it and a state containing dots of its own needs no escaping.

pub fn open<'a>(&self, sealed: &'a str) -> Option<&'a str>

The state a sealed value carries, or None if it was altered.

The comparison is the MAC crate’s own, which is constant-time; a byte-by-byte == would tell an attacker how many leading bytes of a forged MAC were right.

Trait Implementations

impl Clone for StateKey

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for StateKey

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

Never prints the key.