Struct curve25519_dalek::edwards::EdwardsPoint

pub struct EdwardsPoint { /* private fields */ }

An EdwardsPoint represents a point on the Edwards form of Curve25519.

Implementations

impl EdwardsPoint

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 nonspec_map_to_curve<D>(bytes: &[u8]) -> EdwardsPoint

where D: Digest<OutputSize = U64> + Default,

👎Deprecated since 4.0.0: previously named hash_from_bytes, this is not a secure hash function

Available on crate feature digest only.

Maps the digest of the input bytes to the curve. This is NOT a hash-to-curve function, as it produces points with a non-uniform distribution. Rather, it performs something that resembles (but is not) half of the hash_to_curve function from the Elligator2 spec.

impl EdwardsPoint

pub fn mul_base(scalar: &Scalar) -> Self

Fixed-base scalar multiplication by the Ed25519 base point.

Uses precomputed basepoint tables when the precomputed-tables feature is enabled, trading off increased code size for ~4x better performance.

pub fn mul_clamped(self, bytes: [u8; 32]) -> Self

Multiply this point by clamp_integer(bytes). For a description of clamping, see clamp_integer.

pub fn mul_base_clamped(bytes: [u8; 32]) -> Self

Multiply the basepoint by clamp_integer(bytes). For a description of clamping, see clamp_integer.

impl EdwardsPoint

pub fn vartime_double_scalar_mul_basepoint( a: &Scalar, A: &EdwardsPoint, b: &Scalar, ) -> EdwardsPoint

Compute \(aA + bB\) in variable time, where \(B\) is the Ed25519 basepoint.

impl EdwardsPoint

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, 'b> Add<&'b AffineNielsPoint> for &'a EdwardsPoint

type Output = CompletedPoint

The resulting type after applying the + operator.

fn add(self, other: &'b AffineNielsPoint) -> CompletedPoint

Performs the + operation.

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

type Output = EdwardsPoint

The resulting type after applying the + operator.

fn add(self, other: &'b EdwardsPoint) -> EdwardsPoint

Performs the + operation.

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

type Output = EdwardsPoint

The resulting type after applying the + operator.

fn add(self, rhs: &'b EdwardsPoint) -> EdwardsPoint

Performs the + operation.

impl<'a, 'b> Add<&'b ProjectiveNielsPoint> for &'a EdwardsPoint

type Output = CompletedPoint

The resulting type after applying the + operator.

fn add(self, other: &'b ProjectiveNielsPoint) -> CompletedPoint

Performs the + operation.

impl Add<&SubgroupPoint> for &EdwardsPoint

Available on crate feature group only.

type Output = EdwardsPoint

The resulting type after applying the + operator.

fn add(self, other: &SubgroupPoint) -> EdwardsPoint

Performs the + operation.

impl<'b> Add<&'b SubgroupPoint> for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the + operator.

fn add(self, rhs: &'b SubgroupPoint) -> EdwardsPoint

Performs the + operation.

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

type Output = EdwardsPoint

The resulting type after applying the + operator.

fn add(self, rhs: EdwardsPoint) -> EdwardsPoint

Performs the + operation.

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

type Output = EdwardsPoint

The resulting type after applying the + operator.

fn add(self, rhs: SubgroupPoint) -> EdwardsPoint

Performs the + operation.

impl Add<SubgroupPoint> for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the + operator.

fn add(self, rhs: SubgroupPoint) -> EdwardsPoint

Performs the + operation.

impl Add for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the + operator.

fn add(self, rhs: EdwardsPoint) -> EdwardsPoint

Performs the + operation.

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

fn add_assign(&mut self, _rhs: &'b EdwardsPoint)

Performs the += operation.

impl AddAssign<&SubgroupPoint> for EdwardsPoint

Available on crate feature group only.

fn add_assign(&mut self, rhs: &SubgroupPoint)

Performs the += operation.

impl AddAssign<SubgroupPoint> for EdwardsPoint

fn add_assign(&mut self, rhs: SubgroupPoint)

Performs the += operation.

impl AddAssign for EdwardsPoint

fn add_assign(&mut self, rhs: EdwardsPoint)

Performs the += operation.

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 CofactorGroup for EdwardsPoint

Available on crate feature group only.

Ristretto has a cofactor of 1.

type Subgroup = SubgroupPoint

The large prime-order subgroup in which cryptographic operations are performed. If Self implements PrimeGroup, then Self::Subgroup may be Self.

fn clear_cofactor(&self) -> Self::Subgroup

Maps self to the prime-order subgroup by multiplying this element by some k-multiple of the cofactor.

fn into_subgroup(self) -> CtOption<Self::Subgroup>

Returns self if it is contained in the prime-order subgroup.

fn is_torsion_free(&self) -> Choice

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

fn is_small_order(&self) -> Choice

Determines if this element is of small order.

impl ConditionallySelectable for EdwardsPoint

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

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: &EdwardsPoint) -> 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 Default for EdwardsPoint

fn default() -> EdwardsPoint

Returns the “default value” for a type.

impl From<EdwardsPoint> for ExtendedPoint

Available on nightly and curve25519_dalek_backend="simd" only.

fn from(P: EdwardsPoint) -> ExtendedPoint

Converts to this type from the input type.

impl From<ExtendedPoint> for EdwardsPoint

Available on nightly and curve25519_dalek_backend="simd" only.

fn from(P: ExtendedPoint) -> EdwardsPoint

Converts to this type from the input type.

impl From<SubgroupPoint> for EdwardsPoint

Available on crate feature group only.

fn from(p: SubgroupPoint) -> Self

Converts to this type from the input type.

impl Group for EdwardsPoint

Available on crate feature group only.

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

Available on crate feature group only.

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 Identity for EdwardsPoint

fn identity() -> EdwardsPoint

Returns the identity element of the curve. Can be used as a constructor.

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

fn mul(self, point: &'b EdwardsPoint) -> EdwardsPoint

Scalar multiplication: compute scalar * self.

For scalar multiplication of a basepoint, EdwardsBasepointTable is approximately 4x faster.

type Output = EdwardsPoint

The resulting type after applying the * operator.

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

type Output = EdwardsPoint

The resulting type after applying the * operator.

fn mul(self, rhs: &'b EdwardsPoint) -> EdwardsPoint

Performs the * operation.

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

fn mul(self, scalar: &'b Scalar) -> EdwardsPoint

Scalar multiplication: compute scalar * self.

For scalar multiplication of a basepoint, EdwardsBasepointTable is approximately 4x faster.

type Output = EdwardsPoint

The resulting type after applying the * operator.

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

type Output = EdwardsPoint

The resulting type after applying the * operator.

fn mul(self, rhs: &'b Scalar) -> EdwardsPoint

Performs the * operation.

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

type Output = EdwardsPoint

The resulting type after applying the * operator.

fn mul(self, rhs: EdwardsPoint) -> EdwardsPoint

Performs the * operation.

impl Mul<EdwardsPoint> for Scalar

type Output = EdwardsPoint

The resulting type after applying the * operator.

fn mul(self, rhs: EdwardsPoint) -> EdwardsPoint

Performs the * operation.

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

type Output = EdwardsPoint

The resulting type after applying the * operator.

fn mul(self, rhs: Scalar) -> EdwardsPoint

Performs the * operation.

impl Mul<Scalar> for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the * operator.

fn mul(self, rhs: Scalar) -> EdwardsPoint

Performs the * operation.

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

fn mul_assign(&mut self, scalar: &'b Scalar)

Performs the *= operation.

impl MulAssign<Scalar> for EdwardsPoint

fn mul_assign(&mut self, rhs: Scalar)

Performs the *= operation.

impl MultiscalarMul for EdwardsPoint

Available on crate feature alloc only.

type Point = EdwardsPoint

The type of point being multiplied, e.g., RistrettoPoint.

fn multiscalar_mul<I, J>(scalars: I, points: J) -> EdwardsPoint

where I: IntoIterator, I::Item: Borrow<Scalar>, J: IntoIterator, J::Item: Borrow<EdwardsPoint>,

Given an iterator of (possibly secret) scalars and an iterator of public points, compute $$ Q = c_1 P_1 + \cdots + c_n P_n. $$

impl<'a> Neg for &'a EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn neg(self) -> EdwardsPoint

Performs the unary - operation.

impl Neg for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn neg(self) -> EdwardsPoint

Performs the unary - operation.

impl PartialEq for EdwardsPoint

fn eq(&self, other: &EdwardsPoint) -> 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<'a, 'b> Sub<&'b AffineNielsPoint> for &'a EdwardsPoint

type Output = CompletedPoint

The resulting type after applying the - operator.

fn sub(self, other: &'b AffineNielsPoint) -> CompletedPoint

Performs the - operation.

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

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn sub(self, other: &'b EdwardsPoint) -> EdwardsPoint

Performs the - operation.

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

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn sub(self, rhs: &'b EdwardsPoint) -> EdwardsPoint

Performs the - operation.

impl<'a, 'b> Sub<&'b ProjectiveNielsPoint> for &'a EdwardsPoint

type Output = CompletedPoint

The resulting type after applying the - operator.

fn sub(self, other: &'b ProjectiveNielsPoint) -> CompletedPoint

Performs the - operation.

impl Sub<&SubgroupPoint> for &EdwardsPoint

Available on crate feature group only.

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn sub(self, other: &SubgroupPoint) -> EdwardsPoint

Performs the - operation.

impl<'b> Sub<&'b SubgroupPoint> for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn sub(self, rhs: &'b SubgroupPoint) -> EdwardsPoint

Performs the - operation.

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

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn sub(self, rhs: EdwardsPoint) -> EdwardsPoint

Performs the - operation.

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

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn sub(self, rhs: SubgroupPoint) -> EdwardsPoint

Performs the - operation.

impl Sub<SubgroupPoint> for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn sub(self, rhs: SubgroupPoint) -> EdwardsPoint

Performs the - operation.

impl Sub for EdwardsPoint

type Output = EdwardsPoint

The resulting type after applying the - operator.

fn sub(self, rhs: EdwardsPoint) -> EdwardsPoint

Performs the - operation.

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

fn sub_assign(&mut self, _rhs: &'b EdwardsPoint)

Performs the -= operation.

impl SubAssign<&SubgroupPoint> for EdwardsPoint

Available on crate feature group only.

fn sub_assign(&mut self, rhs: &SubgroupPoint)

Performs the -= operation.

impl SubAssign<SubgroupPoint> for EdwardsPoint

fn sub_assign(&mut self, rhs: SubgroupPoint)

Performs the -= operation.

impl SubAssign for EdwardsPoint

fn sub_assign(&mut self, rhs: EdwardsPoint)

Performs the -= operation.

impl<T> Sum<T> for EdwardsPoint

where T: Borrow<EdwardsPoint>,

fn sum<I>(iter: I) -> Self

where I: Iterator<Item = T>,

Takes an iterator and generates Self from the elements by “summing up” the items.

impl VartimeMultiscalarMul for EdwardsPoint

Available on crate feature alloc only.

type Point = EdwardsPoint

The type of point being multiplied, e.g., RistrettoPoint.

fn optional_multiscalar_mul<I, J>(scalars: I, points: J) -> Option<EdwardsPoint>

where I: IntoIterator, I::Item: Borrow<Scalar>, J: IntoIterator<Item = Option<EdwardsPoint>>,

Given an iterator of public scalars and an iterator of Options of points, compute either Some(Q), where $$ Q = c_1 P_1 + \cdots + c_n P_n, $$ if all points were Some(P_i), or else return None.

fn vartime_multiscalar_mul<I, J>(scalars: I, points: J) -> Self::Point

where I: IntoIterator, I::Item: Borrow<Scalar>, J: IntoIterator, J::Item: Borrow<Self::Point>, Self::Point: Clone,

Given an iterator of public scalars and an iterator of public points, compute $$ Q = c_1 P_1 + \cdots + c_n P_n, $$ using variable-time operations.

impl Zeroize for EdwardsPoint

Available on crate feature zeroize only.

fn zeroize(&mut self)

Reset this CompressedEdwardsPoint to the identity element.

impl Copy for EdwardsPoint

impl Eq for EdwardsPoint

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference's “Type Layout” chapter for details on type layout guarantees.

Size: 160 bytes