eddsa

Documentation

Overview

Package eddsa provides a ZKP-circuit function to verify a EdDSA signature.

Index

• func Verify(api frontend.API, sig Signature, msg frontend.Variable, pubKey PublicKey) error
• type PublicKey
• type Signature

Functions

func Verify

func Verify(api frontend.API, sig Signature, msg frontend.Variable, pubKey PublicKey) error

Verify verifies an eddsa signature cf https://en.wikipedia.org/wiki/EdDSA

Types

type PublicKey

type PublicKey struct {
	A     twistededwards.Point
	Curve twistededwards.EdCurve
}

PublicKey stores an eddsa public key (to be used in gnark circuit)

type Signature

type Signature struct {
	R twistededwards.Point
	S frontend.Variable
}

Signature stores a signature (to be used in gnark circuit) An EdDSA signature is a tuple (R,S) where R is a point on the twisted Edwards curve and S a scalar. Since the base field of the twisted Edwards is Fr, the number of points N on the Edwards is < r+1+2sqrt(r)+2 (since the curve has 2 points of multiplicity 2). The subgroup l used in eddsa is <1/2N, so the reduction mod l ensures S < r, therefore there is no risk of overflow.