Struct RecoveryCodes 

pub struct RecoveryCodes { /* private fields */ }

A freshly generated set of recovery codes, in the clear.

The one moment they exist readably. Show them once, tell the person to print them, store only hashed — exactly like a password, and for the same reason: each one is a complete bypass of the second factor.

Implementations

impl RecoveryCodes

pub fn generate(count: usize) -> RecoveryCodes

Mint count codes. Ten is the usual number, and what Laravel issues.

pub fn codes(&self) -> &[String]

The codes, to show once and never again.

pub fn into_codes(self) -> Vec<String>

pub fn hashed(&self) -> Vec<String>

What to store: an argon2 hash of each code.

Argon2 rather than SHA-256, unlike crate::tokens, and the difference is deliberate. An API token is 256 bits of CSPRNG output, so there is nothing to search; a recovery code is fifty bits and is typed by a person, which means it may well be written down, photographed, or entered into the wrong box. Fifty bits is beyond an online attacker but it is not beyond somebody who has stolen the table, and a KDF is what makes the difference. They are also verified once, on a rare path, so the cost buys the protection without being felt.

pub fn hashed_with(&self, cost: Cost) -> Vec<String>

hashed at an explicit cost, for tests. See Cost::FAST, and do not store real codes hashed with it.

Trait Implementations

impl Clone for RecoveryCodes

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 RecoveryCodes

Redacted, for the reason Totp’s is.

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

Formats the value using the given formatter.