Crate dusk_jubjub

This crate provides an implementation of the Jubjub elliptic curve and its associated field arithmetic. See README.md

API

• AffinePoint / ExtendedPoint which are implementations of Jubjub group arithmetic
• AffineNielsPoint / ExtendedNielsPoint which are pre-processed Jubjub points
• Fq, which is the base field of Jubjub
• Fr, which is the scalar field of Jubjub
• batch_normalize for converting many ExtendedPoints into AffinePoints efficiently.

Constant Time

All operations are constant time unless explicitly noted; these functions will contain "vartime" in their name and they will be documented as variable time.

This crate uses the subtle crate to perform constant-time operations.

Modules

elgamal

Implementation of ElGamal encryption scheme with JubJub

Structs

AffineNielsPoint	This is a pre-processed version of an affine point (x, y) in the form (y + x, y - x, x * y * 2d). This can be added to an ExtendedPoint.
AffinePoint	This represents a Jubjub point in the affine (x, y) coordinates.
ExtendedNielsPoint	This is a pre-processed version of an extended point (X, Y, Z, T1, T2) in the form (Y + X, Y - X, Z, T1 * T2 * 2d).
ExtendedPoint	This represents an extended point (X, Y, Z, T1, T2) with Z nonzero, corresponding to the affine point (X/Z, Y/Z). We always have T1 * T2 = XY/Z.
Fq	Represents an element of the scalar field $\mathbb{F}_q$ of the BLS12-381 elliptic curve construction.
Fr	Represents an element of the scalar field $\mathbb{F}_r$ of the Jubjub elliptic curve construction.

Constants

EDWARDS_D	d = -(10240/10241)
EDWARDS_D2	2*EDWARDS_D
GENERATOR	Use a fixed generator point. The point is then reduced according to the prime field. We need only to state the coordinates, so users can exploit its properties which are proven by tests, checking:
GENERATOR_EXTENDED	GENERATOR in ExtendedPoint form
GENERATOR_NUMS	GENERATOR NUMS which is obtained following the specs in: https://app.gitbook.com/@dusk-network/s/specs/specifications/poseidon/pedersen-commitment-scheme The counter = 18 and the hash function used to compute it was blake2b Using: x = 0x5e67b8f316f414f7bd9514c773fd4456931e316a39fe4541921710179df76377
GENERATOR_NUMS_EXTENDED	GENERATOR_NUMS in ExtendedPoint form

Functions

batch_normalize	This takes a mutable slice of ExtendedPoints and "normalizes" them using only a single inversion for the entire batch. This normalization results in all of the points having a Z-coordinate of one. Further, an iterator is returned which can be used to obtain AffinePoints for each element in the slice.
dhke	Compute a shared secret secret · public using DHKE protocol

Type Definitions

Scalar

A better name than Fr.