Struct Cost 

pub struct Cost {
    pub memory_kib: u32,
    pub iterations: u32,
    pub parallelism: u32,
}

How much work one password hash costs.

Fields

memory_kib: u32

Memory used per hash, in kibibytes.

iterations: u32

Passes over that memory.

parallelism: u32

Lanes hashed in parallel.

Implementations

impl Cost

pub const DEFAULT: Cost

The default: 19 MiB of memory, two passes, one lane.

This is OWASP’s first recommended argon2id configuration. Memory is the parameter that actually defends against attackers: a GPU or ASIC can pipeline iterations cheaply but has to buy 19 MiB of fast memory per guess, which is what collapses their parallelism advantage. Two passes is the minimum argon2id allows at this memory size, and one lane keeps the cost predictable on a busy web server that is already running one request per core.

On a modern server this lands around 40 ms per hash — slow enough to make offline cracking expensive, fast enough that a login request does not feel it.

pub const FAST: Cost

The cheapest configuration argon2 accepts.

Deliberately far too weak for real passwords. It exists because a test suite that hashes a dozen passwords at the real cost spends its whole runtime inside argon2, and a slow suite is a suite that stops being run. Never use this to store a password.

Trait Implementations

impl Clone for Cost

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Cost

impl Debug for Cost

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

Formats the value using the given formatter.

impl Default for Cost

fn default() -> Self

Returns the “default value” for a type.

impl Eq for Cost

impl PartialEq for Cost

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Cost