Struct Fp 

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

Canonical field element modulo 2^255 - 19, four little-endian words.

Every operation returns a fully reduced value, so == on the words is field equality and the low bit is the Ed25519 sign.

Tuple Fields

0: [u64; 4]

Implementations

impl Fp

pub const ZERO: Fp

Zero.

pub const ONE: Fp

One.

pub fn from_bytes(bytes: &[u8; 32]) -> Fp

Canonical value from 32 little-endian bytes (reduced modulo p).

Bit 255 is included in the value, so callers decoding a point must clear the sign bit first.

pub fn to_bytes(self) -> [u8; 32]

Canonical little-endian encoding.

pub fn add(self, o: Fp) -> Fp

Sum modulo p.

pub fn sub(self, o: Fp) -> Fp

Difference modulo p.

pub fn mul(self, o: Fp) -> Fp

Product modulo p.

pub fn square(self) -> Fp

Square modulo p.

pub fn pow2k(self, k: u32) -> Fp

self^(2^k).

pub fn invert(self) -> Fp

Multiplicative inverse (zero maps to zero).

Fermat’s little theorem, self^(p-2), by plain square-and-multiply.

pub fn neg(self) -> Fp

Negation modulo p.

pub fn is_negative(self) -> bool

Least-significant bit of the canonical value (Ed25519 “negative”).

pub fn digits17(self) -> [u32; 15]

Fifteen 17-bit digits of the canonical value, least significant first.

This is the digit layout of the RHDL field units (15 x 17 = 255 bits).

pub fn from_digits17(d: &[u32; 15]) -> Fp

Inverse of Self::digits17; the digits must encode a value below p.

The value is not reduced, so out-of-range digits give a non-canonical Fp.

Trait Implementations

impl Clone for Fp

fn clone(&self) -> Fp

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Fp

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

Formats the value using the given formatter.

impl Default for Fp

fn default() -> Fp

Returns the “default value” for a type.

impl PartialEq for Fp

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Copy for Fp

impl Eq for Fp

impl StructuralPartialEq for Fp