ed25519

A drop-in replacement for crypto/ed25519 (godoc, github) with additional functionality. Uses SHA-512 and ECDSA signing algorithm.

Motivation

In order to verify the validity of a given signature, the validator should posses the public key of the signer. It can be sent along with the message and its signature, which means that the overall data being sent includes 256 bits of the public key. Our function allows to extract the public key from the signature (and the message), thus the public key may not be sent, resulting in a smaller transferred data. Note: there's a computational cost for extracting the public key, so one should consider the trade-off between computations and data size.

Usage

import "github.com/spacemeshos/ed25519"

Import package ed25519 from github.com/spacemeshos/ed25519 instead of crypto/ed25519.

Sign2

Sign2 signs the message with privateKey and returns a signature. The signature may be verified using Verify2(), if the signer's public key is known. The signature returned by this method can be used together with the message to extract the public key using ExtractPublicKey() It will panic if len(privateKey) is not PrivateKeySize.

func Sign2(privateKey PrivateKey, message []byte) []byte

ExtractPublicKey

ExtractPublicKey extracts the signer's public key given a message and its signature. It will panic if len(sig) is not SignatureSize.

func ExtractPublicKey(message, sig []byte) PublicKey

Verify2

Verify2 verifies a signature created with Sign2(), assuming the verifier possesses the public key.

func Verify2(publicKey PublicKey, message, sig []byte) bool

Building

go build

Testing

go test ./... -v

Benchmarking

go test -bench=.
go test -bench . github.com/spacemeshos/ed25519/internal/edwards25519

BenchmarkPublicKeyExtraction-12             3000            447515 ns/op

BenchmarkSigning-12                        30000             46100 ns/op
BenchmarkSigningExt-12                     30000             45357 ns/op

BenchmarkKeyGeneration-12                  30000             44649 ns/op

BenchmarkVerification-12                   10000            120082 ns/op
BenchmarkVerificationExt-12                10000            118761 ns/op

Client Example

https://github.com/spacemeshos/ed25519-client