Struct Point 

pub struct Point(EdwardsPoint);

A decompressed point on the Ed25519 elliptic curve.

Tuple Fields

0: EdwardsPoint

Implementations

impl Point

pub fn biased_hash(bytes: [u8; 32]) -> Point

Sample a biased point via a hash function.

This is comparable to Monero’s hash_to_ec function.

This achieves parity with https://github.com/monero-project/monero /blob/389e3ba1df4a6df4c8f9d116aa239d4c00f5bc78/src/crypto/crypto.cpp#L611, inlining the ge_fromfe_frombytes_vartime function (https://github.com/monero-project/monero /blob/389e3ba1df4a6df4c8f9d116aa239d4c00f5bc78/src/crypto/crypto-ops.c#L2309). This implementation runs in constant time.

According to the original authors (https://web.archive.org/web/20201028121818/https://cryptonote.org/whitepaper.pdf), this would implement https://arxiv.org/abs/0706.1448. Shen Noether also describes the algorithm (https://web.getmonero.org/resources/research-lab/pubs/ge_fromfe.pdf), yet without reviewing its security and in a very straight-forward fashion.

In reality, this implements Elligator 2 as detailed in “Elligator: Elliptic-curve points indistinguishable from uniform random strings” (https://eprint.iacr.org/2013/325). Specifically, Section 5.5 details the application of Elligator 2 to Curve25519, after which the result is mapped to Ed25519.

As this only applies Elligator 2 once, it’s limited to a subset of points where a certain derivative of their u coordinates (in Montgomery form) are quadratic residues. It’s biased accordingly. The yielded points SHOULD still have uniform relations to each other however.

pub fn compress(self) -> CompressedPoint

Compress a point to a CompressedPoint.

#[doc(hidden)] pub fn from(point: EdwardsPoint) -> Point

Create a Point from a curve25519_dalek::EdwardsPoint.

This is hidden as it is not part of our API commitment. No guarantees are made for it.

#[doc(hidden)] pub fn into(self) -> EdwardsPoint

Create a curve25519_dalek::EdwardsPoint from a Point.

This is hidden as it is not part of our API commitment. No guarantees are made for it.

#[doc(hidden)] pub fn key_image(self) -> Option<EdwardsPoint>

Interpret a point as a key image.

This is hidden as it is not part of our API commitment. No guarantees are made for it.

Trait Implementations

impl Clone for Point

fn clone(&self) -> Point

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl ConditionallySelectable for Point

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

Select a or b according to choice.

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

Conditionally assign other to self, according to choice.

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

Conditionally swap self and other if choice == 1; otherwise, reassign both unto themselves.

impl ConstantTimeEq for Point

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

Determine if two items are equal.

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

Determine if two items are NOT equal.

impl Debug for Point

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

Formats the value using the given formatter.

impl Eq for Point

#[doc(hidden)] fn assert_receiver_is_total_eq(&self)

impl PartialEq for Point

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

This defers to ConstantTimeEq::ct_eq.

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 Zeroize for Point

fn zeroize(&mut self)

Zero out this object from memory using Rust intrinsics which ensure the zeroization operation is not “optimized away” by the compiler.

impl Copy for Point

impl TrivialClone for Point