Struct ZeroizingGuard 

pub struct ZeroizingGuard<T>
where
    T: FastZeroizable + ZeroizationProbe + Default,
{ /* private fields */ }

RAII guard for owned values that automatically zeroizes on drop.

ZeroizingGuard wraps an owned value T in a Box and ensures that it is zeroized when the guard is dropped. This is useful for returning sensitive data from functions while guaranteeing automatic cleanup.

Design

• Wraps Box<T> (owns the value on the heap, avoiding stack copies)
• Takes &mut T in constructor and swaps with T::default(), zeroizing the source
• Implements Deref and DerefMut for convenient access
• Zeroizes inner on drop
• Contains ZeroizeOnDropSentinel to verify zeroization happened

Usage

use redoubt_zero_core::{ZeroizingGuard, ZeroizationProbe, FastZeroizable};

fn create_sensitive_data() -> ZeroizingGuard<u64> {
    let mut value = 12345u64;
    ZeroizingGuard::from_mut(&mut value)
}

{
    let guard = create_sensitive_data();
    assert_eq!(*guard, 12345);
} // guard drops here → value is zeroized

Panics

The guard panics on drop if the wrapped value’s ZeroizeOnDropSentinel was not marked as zeroized. This ensures zeroization invariants are enforced.

Implementations

impl<T> ZeroizingGuard<T>

where T: FastZeroizable + ZeroizationProbe + Default,

pub fn from_mut(value: &mut T) -> Self

Creates a new guard by swapping the value from the source and zeroizing it.

The source location is swapped with T::default() and then zeroized, ensuring no copies of the sensitive data remain on the stack. The value is stored in a Box on the heap.

Example

use redoubt_zero_core::{ZeroizingGuard, ZeroizationProbe};

let mut value = 42u32;
let guard = ZeroizingGuard::from_mut(&mut value);
assert_eq!(*guard, 42);
assert!(value.is_zeroized()); // source is zeroized

pub fn from_default() -> Self

Creates a new guard with the default value of T.

This is a convenience method equivalent to:

let mut value = T::default();
ZeroizingGuard::from_mut(&mut value)

Example

use redoubt_zero_core::{ZeroizingGuard, ZeroizationProbe};

let guard: ZeroizingGuard<u64> = ZeroizingGuard::from_default();
assert!(guard.is_zeroized());

Trait Implementations

impl<T> AssertZeroizeOnDrop for ZeroizingGuard<T>

where T: FastZeroizable + ZeroizationProbe + Default,

fn clone_sentinel(&self) -> ZeroizeOnDropSentinel

Clones the internal ZeroizeOnDropSentinel for verification.

fn assert_zeroize_on_drop(self)

Asserts that zeroization happens when this value is dropped.

impl<T> Debug for ZeroizingGuard<T>

where T: FastZeroizable + ZeroizationProbe + Default,

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

Formats the value using the given formatter.

impl<T> Deref for ZeroizingGuard<T>

where T: FastZeroizable + ZeroizationProbe + Default,

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T> DerefMut for ZeroizingGuard<T>

where T: FastZeroizable + ZeroizationProbe + Default,

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<T> Drop for ZeroizingGuard<T>

where T: FastZeroizable + ZeroizationProbe + Default,

fn drop(&mut self)

Executes the destructor for this type.

impl<T> FastZeroizable for ZeroizingGuard<T>

where T: FastZeroizable + ZeroizationProbe + Default,

fn fast_zeroize(&mut self)

Zeroizes the value in place.

impl<T> ZeroizationProbe for ZeroizingGuard<T>

where T: FastZeroizable + ZeroizationProbe + Default,

fn is_zeroized(&self) -> bool

Returns true if the value is zeroized (all bytes are 0).