Struct oberon::inner_types::elliptic_curve::bigint::subtle::Choice
source · pub struct Choice(_);Expand description
The Choice struct represents a choice for use in conditional assignment.
It is a wrapper around a u8, which should have the value either 1 (true)
or 0 (false).
The conversion from u8 to Choice passes the value through an optimization
barrier, as a best-effort attempt to prevent the compiler from inferring that
the Choice value is a boolean. This strategy is based on Tim Maclean’s
work on rust-timing-shield, which attempts to provide
a more comprehensive approach for preventing software side-channels in Rust
code.
The Choice struct implements operators for AND, OR, XOR, and NOT, to allow
combining Choice values. These operations do not short-circuit.
Implementations§
Trait Implementations§
source§impl BitAndAssign<Choice> for Choice
impl BitAndAssign<Choice> for Choice
source§fn bitand_assign(&mut self, rhs: Choice)
fn bitand_assign(&mut self, rhs: Choice)
Performs the
&= operation. Read moresource§impl BitOrAssign<Choice> for Choice
impl BitOrAssign<Choice> for Choice
source§fn bitor_assign(&mut self, rhs: Choice)
fn bitor_assign(&mut self, rhs: Choice)
Performs the
|= operation. Read moresource§impl BitXorAssign<Choice> for Choice
impl BitXorAssign<Choice> for Choice
source§fn bitxor_assign(&mut self, rhs: Choice)
fn bitxor_assign(&mut self, rhs: Choice)
Performs the
^= operation. Read moresource§impl ConditionallySelectable for Choice
impl ConditionallySelectable for Choice
source§impl ConstantTimeEq for Choice
impl ConstantTimeEq for Choice
source§impl From<Choice> for bool
impl From<Choice> for bool
source§fn from(source: Choice) -> bool
fn from(source: Choice) -> bool
Convert the Choice wrapper into a bool, depending on whether
the underlying u8 was a 0 or a 1.
Note
This function exists to avoid having higher-level cryptographic protocol implementations duplicating this pattern.
The intended use case for this conversion is at the end of a
higher-level primitive implementation: for example, in checking a keyed
MAC, where the verification should happen in constant-time (and thus use
a Choice) but it is safe to return a bool at the end of the
verification.
impl Copy for Choice
Auto Trait Implementations§
impl RefUnwindSafe for Choice
impl Send for Choice
impl Sync for Choice
impl Unpin for Choice
impl UnwindSafe for Choice
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