Struct dalek_ff_group::EdwardsPoint

pub struct EdwardsPoint(pub EdwardsPoint);

Wrapper around the dalek Point type. For Ed25519, this is restricted to the prime subgroup.

Tuple Fields

0: EdwardsPoint

Implementations

impl EdwardsPoint

pub fn mul_by_cofactor(&self) -> EdwardsPoint

Methods from Deref<Target = DEdwardsPoint>

pub fn to_montgomery(&self) -> MontgomeryPoint

Convert this EdwardsPoint on the Edwards model to the corresponding MontgomeryPoint on the Montgomery model.

This function has one exceptional case; the identity point of the Edwards curve is sent to the 2-torsion point \((0,0)\) on the Montgomery curve.

Note that this is a one-way conversion, since the Montgomery model does not retain sign information.

pub fn compress(&self) -> CompressedEdwardsY

Compress this point to CompressedEdwardsY format.

pub fn mul_by_cofactor(&self) -> EdwardsPoint

Multiply by the cofactor: return \([8]P\).

pub fn is_small_order(&self) -> bool

Determine if this point is of small order.

Return

• true if self is in the torsion subgroup \( \mathcal E[8] \);
• false if self is not in the torsion subgroup \( \mathcal E[8] \).

Example

use curve25519_dalek::constants;

// Generator of the prime-order subgroup
let P = constants::ED25519_BASEPOINT_POINT;
// Generator of the torsion subgroup
let Q = constants::EIGHT_TORSION[1];

// P has large order
assert_eq!(P.is_small_order(), false);

// Q has small order
assert_eq!(Q.is_small_order(), true);

pub fn is_torsion_free(&self) -> bool

Determine if this point is “torsion-free”, i.e., is contained in the prime-order subgroup.

Return

• true if self has zero torsion component and is in the prime-order subgroup;
• false if self has a nonzero torsion component and is not in the prime-order subgroup.

Example

use curve25519_dalek::constants;

// Generator of the prime-order subgroup
let P = constants::ED25519_BASEPOINT_POINT;
// Generator of the torsion subgroup
let Q = constants::EIGHT_TORSION[1];

// P is torsion-free
assert_eq!(P.is_torsion_free(), true);

// P + Q is not torsion-free
assert_eq!((P+Q).is_torsion_free(), false);

Trait Implementations

impl<'a> Add<&'a EdwardsPoint> for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the + operator.

fn add(self, other: &'a EdwardsPoint) -> Self::Output

Performs the + operation.

impl Add for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the + operator.

fn add(self, other: EdwardsPoint) -> Self::Output

Performs the + operation.

impl<'a> AddAssign<&'a EdwardsPoint> for EdwardsPoint

fn add_assign(&mut self, other: &'a EdwardsPoint)

Performs the += operation.

impl AddAssign for EdwardsPoint

fn add_assign(&mut self, other: EdwardsPoint)

Performs the += operation.

impl Borrow<EdwardsPoint> for &EdwardsPoint

fn borrow(&self) -> &DEdwardsPoint

Immutably borrows from an owned value.

impl Borrow<EdwardsPoint> for EdwardsPoint

fn borrow(&self) -> &DEdwardsPoint

Immutably borrows from an owned value.

impl Clone for EdwardsPoint

fn clone(&self) -> EdwardsPoint

Returns a copy of the value.

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

Performs copy-assignment from source.

impl ConditionallySelectable for EdwardsPoint

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

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 EdwardsPoint

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

Determine if two items are equal.

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

Determine if two items are NOT equal.

impl Debug for EdwardsPoint

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

Formats the value using the given formatter.

impl Deref for EdwardsPoint

type Target = EdwardsPoint

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl Group for EdwardsPoint

type Scalar = Scalar

Scalars modulo the order of this group’s scalar field.

fn random(rng: impl RngCore) -> Self

Returns an element chosen uniformly at random from the non-identity elements of this group.

fn identity() -> Self

Returns the additive identity, also known as the “neutral element”.

fn generator() -> Self

Returns a fixed generator of the prime-order subgroup.

fn is_identity(&self) -> Choice

Determines if this point is the identity.

fn double(&self) -> Self

Doubles this element.

impl GroupEncoding for EdwardsPoint

type Repr = [u8; 32]

The encoding of group elements.

fn from_bytes(bytes: &Self::Repr) -> CtOption<Self>

Attempts to deserialize a group element from its encoding.

fn from_bytes_unchecked(bytes: &Self::Repr) -> CtOption<Self>

Attempts to deserialize a group element, not checking if the element is valid.

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

Converts this element into its byte encoding. This may or may not support encoding the identity.

impl Hash for EdwardsPoint

fn hash<H: Hasher>(&self, state: &mut H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl<'a> Mul<&'a Scalar> for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the * operator.

fn mul(self, other: &'a Scalar) -> Self::Output

Performs the * operation.

impl Mul<Scalar> for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the * operator.

fn mul(self, other: Scalar) -> Self::Output

Performs the * operation.

impl<'a> MulAssign<&'a Scalar> for EdwardsPoint

fn mul_assign(&mut self, other: &'a Scalar)

Performs the *= operation.

impl MulAssign<Scalar> for EdwardsPoint

fn mul_assign(&mut self, other: Scalar)

Performs the *= operation.

impl Neg for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn neg(self) -> Self::Output

Performs the unary - operation.

impl PartialEq for EdwardsPoint

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

This method tests for self and other values to be equal, and is used by ==.

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

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

impl<'a> Sub<&'a EdwardsPoint> for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn sub(self, other: &'a EdwardsPoint) -> Self::Output

Performs the - operation.

impl Sub for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn sub(self, other: EdwardsPoint) -> Self::Output

Performs the - operation.

impl<'a> SubAssign<&'a EdwardsPoint> for EdwardsPoint

fn sub_assign(&mut self, other: &'a EdwardsPoint)

Performs the -= operation.

impl SubAssign for EdwardsPoint

fn sub_assign(&mut self, other: EdwardsPoint)

Performs the -= operation.

impl<'a> Sum<&'a EdwardsPoint> for EdwardsPoint

fn sum<I: Iterator<Item = &'a EdwardsPoint>>(iter: I) -> EdwardsPoint

Method which takes an iterator and generates Self from the elements by “summing up” the items.

impl Sum for EdwardsPoint

fn sum<I: Iterator<Item = EdwardsPoint>>(iter: I) -> EdwardsPoint

Method which takes an iterator and generates Self from the elements by “summing up” the items.

impl Zeroize for EdwardsPoint

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 EdwardsPoint

impl Eq for EdwardsPoint

impl PrimeGroup for EdwardsPoint

impl StructuralPartialEq for EdwardsPoint