Struct Fn 

pub struct Fn(pub [u64; 4]);

The P-256 scalar ring, Z/nZ where n is the order of the base point.

Values are held in Montgomery form (a * R mod m). Arithmetic is branch-free and carries no data-dependent memory access.

Tuple Fields

0: [u64; 4]

Implementations

impl Fn

pub const MODULUS: [u64; 4]

The modulus, as little-endian 64-bit limbs.

pub const fn to_mont(limbs: [u64; 4]) -> Self

Convert a plain integer into Montgomery form.

pub const fn from_mont(&self) -> [u64; 4]

Convert out of Montgomery form.

pub fn square_n(&self, n: usize) -> Self

Repeated squaring, self^(2^n).

pub fn pow(&self, exponent: &[u64; 4]) -> Self

Exponentiation by a public exponent, square-and-multiply.

The exponent is always a fixed constant here (m - 2 for inversion, (p + 1) / 4 for square roots), so branching on its bits leaks nothing; the base stays secret throughout.

Trait Implementations

impl Clone for Fn

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for Fn

impl Debug for Fn

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

Formats the value using the given formatter.

impl Eq for Fn

impl Field for Fn

const ZERO: Self

The additive identity.

const ONE: Self

The multiplicative identity.

const BYTE_LEN: usize = 32

Width of Self::Bytes.

type Bytes = [u8; 32]

The canonical big-endian byte encoding.

fn add(&self, other: &Self) -> Self

Ring addition.

fn sub(&self, other: &Self) -> Self

Ring subtraction.

fn mul(&self, other: &Self) -> Self

Ring multiplication.

fn square(&self) -> Self

Squaring.

fn double(&self) -> Self

Doubling, cheaper than a general addition.

fn triple(&self) -> Self

Tripling, used by the a = -3 doubling formula.

fn neg(&self) -> Self

Negation.

fn invert(&self) -> Self

Multiplicative inverse, with inverse(0) == 0.

fn from_bytes(bytes: &Self::Bytes) -> Option<Self>

Decode a canonical encoding, rejecting values at or above the modulus.

fn from_bytes_reduced(bytes: &Self::Bytes) -> Self

Decode, reducing rather than rejecting.

fn to_bytes(&self) -> Self::Bytes

Encode canonically.

fn zero_bytes() -> Self::Bytes

Build a zeroed byte buffer of the right width.

fn is_zero(&self) -> Choice

Constant-time test for zero.

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

Constant-time equality.

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

Constant-time conditional move.

fn is_odd(&self) -> Choice

Whether the canonical integer is odd — the SEC1 compression sign bit.

impl PartialEq for Fn

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for Fn