tc_constant_time 0.1.0

Constant-time selection, comparison, and conditional arithmetic primitives.
Documentation 
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//! Constant-time comparison and conditional updates for fixed-size arrays.

use crate::{Choice, ConditionallyNegatable, ConditionallySelectable, ConstantTimeEq};

impl<T: ConditionallySelectable, const N: usize> ConditionallySelectable for [T; N] {
    fn conditional_select(a: &Self, b: &Self, choice: Choice) -> Self {
        core::array::from_fn(|i| T::conditional_select(&a[i], &b[i], choice))
    }

    fn conditional_assign(&mut self, other: &Self, choice: Choice) {
        for (value, source) in self.iter_mut().zip(other) {
            value.conditional_assign(source, choice);
        }
    }

    fn conditional_swap(a: &mut Self, b: &mut Self, choice: Choice) {
        for (left, right) in a.iter_mut().zip(b) {
            T::conditional_swap(left, right, choice);
        }
    }
}

impl<T: ConditionallyNegatable, const N: usize> ConditionallyNegatable for [T; N] {
    fn conditional_negate(&mut self, choice: Choice) {
        for value in self {
            value.conditional_negate(choice);
        }
    }
}

impl<T: ConstantTimeEq, const N: usize> ConstantTimeEq for [T; N] {
    fn ct_eq(&self, rhs: &Self) -> Choice {
        self.as_slice().ct_eq(rhs.as_slice())
    }
}