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Trait subtle::ConditionallySelectable

source · [−]
pub trait ConditionallySelectable: Copy {
    fn conditional_select(a: &Self, b: &Self, choice: Choice) -> Self;

    fn conditional_assign(&mut self, other: &Self, choice: Choice) { ... }
    fn conditional_swap(a: &mut Self, b: &mut Self, choice: Choice) { ... }
}
Expand description

A type which can be conditionally selected in constant time.

This trait also provides generic implementations of conditional assignment and conditional swaps.

Required Methods

Select a or b according to choice.

Returns
  • a if choice == Choice(0);
  • b if choice == Choice(1).

This function should execute in constant time.

Example
use subtle::ConditionallySelectable;
let x: u8 = 13;
let y: u8 = 42;

let z = u8::conditional_select(&x, &y, 0.into());
assert_eq!(z, x);
let z = u8::conditional_select(&x, &y, 1.into());
assert_eq!(z, y);

Provided Methods

Conditionally assign other to self, according to choice.

This function should execute in constant time.

Example
use subtle::ConditionallySelectable;
let mut x: u8 = 13;
let mut y: u8 = 42;

x.conditional_assign(&y, 0.into());
assert_eq!(x, 13);
x.conditional_assign(&y, 1.into());
assert_eq!(x, 42);

Conditionally swap self and other if choice == 1; otherwise, reassign both unto themselves.

This function should execute in constant time.

Example
use subtle::ConditionallySelectable;
let mut x: u8 = 13;
let mut y: u8 = 42;

u8::conditional_swap(&mut x, &mut y, 0.into());
assert_eq!(x, 13);
assert_eq!(y, 42);
u8::conditional_swap(&mut x, &mut y, 1.into());
assert_eq!(x, 42);
assert_eq!(y, 13);

Implementations on Foreign Types

Implementors