eddsa

Documentation

Overview

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

Index

• func Verify(cs *frontend.ConstraintSystem, sig Signature, msg frontend.Variable, ...) error
• type PublicKey
• type Signature

Functions

func Verify

func Verify(cs *frontend.ConstraintSystem, 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
	S1, S2 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. S can be greater than r, the size of the zk snark field, and must not be reduced modulo r. Therefore it is split in S1 and S2, such that if r is n-bits long, S = 2^(n/2)*S1 + S2. In other words, S is written S1S2 in basis 2^(n/2).