Struct KdfLimit 

#[non_exhaustive]
pub struct KdfLimit {
    pub max_mem_cost_kib: u32,
    pub max_time_cost: u32,
    pub max_lanes: u32,
}

Local policy limit for Argon2id work accepted during decryption.

A v1 file or private.key stores its Argon2id parameters in the cleartext header. When processing untrusted input, KdfLimit prevents a malicious header from forcing arbitrarily expensive key derivation: any structurally valid input whose memory cost, time cost, or lane count exceeds the configured cap is rejected before Argon2id runs. If no limit is configured on a decryptor, the library applies KdfLimit::default: memory is capped at the writer’s default (1 GiB), while time cost and lanes are capped at the v1 format maximum, so those two reject nothing the structural check would not already reject.

Construct with KdfLimit::new for KiB or KdfLimit::from_mib for MiB, optionally tighten time cost or lanes with KdfLimit::with_max_time_cost / KdfLimit::with_max_lanes, then pass the result to crate::PassphraseDecryptor::kdf_limit or crate::PrivateKeyDecryptor::kdf_limit. The struct is #[non_exhaustive] so future releases can add further limit dimensions without a breaking change.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

max_mem_cost_kib: u32

Maximum accepted memory cost in KiB.

max_time_cost: u32

Maximum accepted time cost (Argon2id iteration count). Defaults to the v1 format maximum, so it rejects nothing the structural check accepts unless tightened with KdfLimit::with_max_time_cost.

max_lanes: u32

Maximum accepted lane count (Argon2id parallelism). Defaults to the v1 format maximum, so it rejects nothing the structural check accepts unless tightened with KdfLimit::with_max_lanes.

Implementations

impl KdfLimit

pub fn new(max_mem_cost_kib: u32) -> Self

Builds a limit from a KiB memory value, leaving the time-cost and lane caps at their defaults (the v1 format maximum). Only memory is constrained unless with_max_time_cost or with_max_lanes tightens the others.

pub fn from_mib(mib: u32) -> Result<Self, CryptoError>

Builds a limit from MiB, leaving the time-cost and lane caps at their defaults (the v1 format maximum).

Errors

Returns CryptoError::InvalidInput if mib * 1024 overflows u32.

pub fn with_max_time_cost(self, max_time_cost: u32) -> Self

Sets the accepted Argon2id time-cost cap. Values at or above the v1 format maximum are equivalent to the structural maximum, because the structural check already rejects anything higher. Lower values make decryption refuse an otherwise-valid header whose iteration count exceeds the cap.

pub fn with_max_lanes(self, max_lanes: u32) -> Self

Sets the accepted Argon2id lane-count cap. Values at or above the v1 format maximum are equivalent to the structural maximum; lower values make decryption refuse an otherwise-valid header whose lane count exceeds the cap.

Trait Implementations

impl Clone for KdfLimit

fn clone(&self) -> KdfLimit

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for KdfLimit

impl Debug for KdfLimit

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

Formats the value using the given formatter.

impl Default for KdfLimit

fn default() -> Self

Returns the “default value” for a type.

impl Eq for KdfLimit

impl PartialEq for KdfLimit

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for KdfLimit