Struct Choice 

pub struct Choice(/* private fields */);

A boolean that can be combined and consumed without secret-dependent branching.

Internally a u8 that is always 0 (false) or 1 (true). Combine choices with the bitwise operators (&, |, ^, !); turn one into a real bool only at the end of a computation, once the result is public — that conversion is not constant time.

Implementations

impl Choice

pub fn unwrap_u8(self) -> u8

Returns the inner 0/1 byte.

Trait Implementations

impl BitAnd for Choice

type Output = Choice

The resulting type after applying the & operator.

fn bitand(self, rhs: Choice) -> Choice

Performs the & operation.

impl BitAndAssign for Choice

fn bitand_assign(&mut self, rhs: Choice)

Performs the &= operation.

impl BitOr for Choice

type Output = Choice

The resulting type after applying the | operator.

fn bitor(self, rhs: Choice) -> Choice

Performs the | operation.

impl BitOrAssign for Choice

fn bitor_assign(&mut self, rhs: Choice)

Performs the |= operation.

impl BitXor for Choice

type Output = Choice

The resulting type after applying the ^ operator.

fn bitxor(self, rhs: Choice) -> Choice

Performs the ^ operation.

impl BitXorAssign for Choice

fn bitxor_assign(&mut self, rhs: Choice)

Performs the ^= operation.

impl Clone for Choice

fn clone(&self) -> Choice

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl ConditionallySelectable for Choice

fn conditional_select(a: &Choice, b: &Choice, choice: Choice) -> Choice

Returns a if choice is true, otherwise b, without a secret-dependent branch.

fn conditional_assign(&mut self, other: &Self, choice: Choice)

Sets self to other if choice is true, otherwise leaves it unchanged.

fn conditional_swap(a: &mut Self, b: &mut Self, choice: Choice)

Swaps a and b if choice is true, otherwise leaves them unchanged.

impl ConstantTimeEq for Choice

fn ct_eq(&self, other: &Choice) -> Choice

Returns a Choice that is true iff self and other are equal.

fn ct_ne(&self, other: &Self) -> Choice

Returns a Choice that is true iff self and other differ.

impl Copy for Choice

impl Debug for Choice

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

Formats the value using the given formatter.

impl Default for Choice

fn default() -> Choice

Returns the “default value” for a type.

impl From<Choice> for bool

fn from(choice: Choice) -> Self

Converts to a plain bool. Not constant time — use only on values that are no longer secret.

impl From<u8> for Choice

fn from(value: u8) -> Self

Wraps a 0/1 byte as a Choice.

Debug builds assert the input is 0 or 1. Release builds mask value & 1 so an out-of-domain byte is silently coerced to a valid Choice rather than corrupting downstream constant-time selects. (Internal callers should still keep the bit clean — the mask is a safety net, not a license to pass arbitrary bytes.)

impl Not for Choice

type Output = Choice

The resulting type after applying the ! operator.

fn not(self) -> Choice

Performs the unary ! operation.