Crate dusk_jubjub

source ·
Expand description

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

§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.
  • JubJubAffine / JubJubExtended as convenient type aliases.

§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.

Structs§

  • AffineNielsPoint
    This is a pre-processed version of an affine point (u, v) in the form (v + u, v - u, u * v * 2d). This can be added to an ExtendedPoint.
  • AffinePoint
    This represents a Jubjub point in the affine (u, v) coordinates.
  • BlsScalar
    Represents an element of the scalar field $\mathbb{F}_q$ of the BLS12-381 elliptic curve construction.
  • ExtendedNielsPoint
    This is a pre-processed version of an extended point (U, V, Z, T1, T2) in the form (V + U, V - U, Z, T1 * T2 * 2d).
  • ExtendedPoint
    This represents an extended point (U, V, Z, T1, T2) with Z nonzero, corresponding to the affine point (U/Z, V/Z). We always have T1 * T2 = UV/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.
  • SubgroupPoint
    This represents a point in the prime-order subgroup of Jubjub, in extended coordinates.

Constants§

  • EDWARDS_D
    d = -(10240/10241)
  • 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 JubJubExtended 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 y = 0x43d80eb3b2f3eb1b7b162dbeeb3b34fd9949ba0f82a5507a6705b707162e3ef8
  • GENERATOR_NUMS_EXTENDED
    GENERATOR_NUMS in JubJubExtended 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 Aliases§