Struct NonceLog 

pub struct NonceLog { /* private fields */ }

A record of already used pairing nonces, used to reject replays.

What it protects against

The pairing protocol already makes each session single-use (PendingSession::accept takes self, and every begin generates a fresh ephemeral key and nonce). This record covers the layer above: a caller that persists nonces can still recognise “this QR code / this session has already been handled” after a restart, instead of accepting it again because in-memory state was lost.

Bounded capacity

Pairing happens at the pace of manual user actions, so a few hundred entries are plenty. An unbounded record would be a resource an attacker could exhaust by starting pairings it never finishes. When the record is full the oldest entry is evicted; the session behind an evicted nonce ended long ago, so replaying it could not succeed anyway.

Implementations

impl NonceLog

pub const DEFAULT_CAPACITY: usize = 256

Number of nonces kept by default.

pub fn new() -> Self

Create an empty record.

pub fn len(&self) -> usize

Number of entries.

pub fn is_empty(&self) -> bool

Whether the record is empty.

pub fn is_used(&self, nonce: &[u8; 32]) -> bool

Whether this nonce has already been used.

pub fn record(&mut self, nonce: [u8; 32]) -> bool

Record a nonce.

false means this nonce was recorded before (that is, this is a replay) and the caller should reject the operation; true means it was recorded.

Trait Implementations

impl Clone for NonceLog

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 NonceLog

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

Formats the value using the given formatter.

impl Default for NonceLog

fn default() -> Self

Returns the “default value” for a type.