mirror of
https://source.quilibrium.com/quilibrium/ceremonyclient.git
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321 lines
8.2 KiB
Go
321 lines
8.2 KiB
Go
//
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// Copyright Coinbase, Inc. All Rights Reserved.
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//
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// SPDX-License-Identifier: Apache-2.0
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//
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// This file implements the Ed25519 signature algorithm. See
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// https://ed25519.cr.yp.to/.
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//
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// These functions are also compatible with the “Ed25519” function defined in
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// RFC 8032. However, unlike RFC 8032's formulation, this package's private key
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// representation includes a public key suffix to make multiple signing
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// operations with the same key more efficient. This package refers to the RFC
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// 8032 private key as the “seed”.
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// This code is a port of the public domain, “ref10” implementation of ed25519
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// from SUPERCOP.
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package nem
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import (
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"bytes"
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"crypto"
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cryptorand "crypto/rand"
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"fmt"
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"io"
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"strconv"
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"filippo.io/edwards25519"
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"golang.org/x/crypto/sha3"
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"source.quilibrium.com/quilibrium/monorepo/nekryptology/internal"
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)
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const (
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// PublicKeySize is the size, in bytes, of public keys as used in this package.
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PublicKeySize = 32
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// PrivateKeySize is the size, in bytes, of private keys as used in this package.
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PrivateKeySize = 64
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// SignatureSize is the size, in bytes, of signatures generated and verified by this package.
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SignatureSize = 64
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// SeedSize is the size, in bytes, of private key seeds. These are the private key representations used by RFC 8032.
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SeedSize = 32
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)
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// PublicKey is the type of Ed25519 public keys.
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type PublicKey []byte
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// PrivateKey is the type of Ed25519 private keys. It implements crypto.Signer.
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type PrivateKey []byte
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// Bytes returns the publicKey in byte array
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func (p PublicKey) Bytes() []byte {
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return p
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}
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// Public returns the PublicKey corresponding to priv.
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func (priv PrivateKey) Public() crypto.PublicKey {
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publicKey := make([]byte, PublicKeySize)
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copy(publicKey, priv[32:])
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return PublicKey(publicKey)
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}
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func Keccak512(data []byte) ([]byte, error) {
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k512 := sha3.NewLegacyKeccak512()
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_, err := k512.Write(data)
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if err != nil {
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return nil, err
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}
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return k512.Sum(nil), nil
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}
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// Seed returns the private key seed corresponding to priv. It is provided for
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// interoperability with RFC 8032. RFC 8032's private keys correspond to seeds
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// in this package.
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func (priv PrivateKey) Seed() []byte {
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seed := make([]byte, SeedSize)
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copy(seed, priv[:32])
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return seed
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}
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// Sign signs the given message with priv.
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// Ed25519 performs two passes over messages to be signed and therefore cannot
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// handle pre-hashed messages. Thus opts.HashFunc() must return zero to
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// indicate the message hasn't been hashed. This can be achieved by passing
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// crypto.Hash(0) as the value for opts.
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func (priv PrivateKey) Sign(rand io.Reader, message []byte, opts crypto.SignerOpts) (signature []byte, err error) {
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if opts.HashFunc() != crypto.Hash(0) {
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return nil, fmt.Errorf("ed25519: cannot sign hashed message")
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}
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sig, err := Sign(priv, message)
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if err != nil {
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return nil, err
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}
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return sig, nil
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}
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// GenerateKey generates a public/private key pair using entropy from rand.
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// If rand is nil, crypto/rand.Reader will be used.
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func GenerateKey(rand io.Reader) (PublicKey, PrivateKey, error) {
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if rand == nil {
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rand = cryptorand.Reader
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}
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seed := make([]byte, SeedSize)
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if _, err := io.ReadFull(rand, seed); err != nil {
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return nil, nil, err
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}
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privateKey, err := NewKeyFromSeed(seed)
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if err != nil {
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return nil, nil, err
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}
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publicKey := make([]byte, PublicKeySize)
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copy(publicKey, privateKey[32:])
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return publicKey, privateKey, nil
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}
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// NewKeyFromSeed calculates a private key from a seed. It will panic if
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// len(seed) is not SeedSize. This function is provided for interoperability
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// with RFC 8032. RFC 8032's private keys correspond to seeds in this
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// package.
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func NewKeyFromSeed(seed []byte) (PrivateKey, error) {
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// Outline the function body so that the returned key can be stack-allocated.
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privateKey := make([]byte, PrivateKeySize)
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err := newKeyFromSeed(privateKey, seed)
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if err != nil {
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return nil, err
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}
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return privateKey, nil
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}
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func newKeyFromSeed(privateKey, seed []byte) error {
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if l := len(seed); l != SeedSize {
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return fmt.Errorf("ed25519: bad seed length: " + strconv.Itoa(l))
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}
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// Weird required step to get compatibility with the NEM test vectors
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// Have to reverse the bytes from the given seed
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digest, err := Keccak512(internal.ReverseScalarBytes(seed))
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if err != nil {
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return err
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}
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sc, err := edwards25519.NewScalar().SetBytesWithClamping(digest[:32])
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if err != nil {
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return err
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}
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A := edwards25519.Point{}
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A.ScalarBaseMult(sc)
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publicKeyBytes := A.Bytes()
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copy(privateKey, seed)
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copy(privateKey[32:], publicKeyBytes[:])
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return nil
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}
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// Sign signs the message with privateKey and returns a signature. It will
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// panic if len(privateKey) is not PrivateKeySize.
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func Sign(privateKey PrivateKey, message []byte) ([]byte, error) {
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// Outline the function body so that the returned signature can be
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// stack-allocated.
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signature := make([]byte, SignatureSize)
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err := sign(signature, privateKey, message)
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if err != nil {
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return nil, err
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}
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return signature, nil
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}
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func sign(signature, privateKey, message []byte) error {
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if l := len(privateKey); l != PrivateKeySize {
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return fmt.Errorf("ed25519: bad private key length: " + strconv.Itoa(l))
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}
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seed := privateKey[:32]
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digest, err := Keccak512(internal.ReverseScalarBytes(seed))
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if err != nil {
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return err
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}
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// H(seed) ie. privkey
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expandedSecretKey := digest[:32]
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sc, err := edwards25519.NewScalar().SetBytesWithClamping(expandedSecretKey)
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if err != nil {
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return err
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}
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// r = H(H(seed) + msg)
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hEngine := sha3.NewLegacyKeccak512()
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_, err = hEngine.Write(digest[32:])
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if err != nil {
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return err
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}
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_, err = hEngine.Write(message)
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if err != nil {
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return err
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}
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var hOut1 [64]byte
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hEngine.Sum(hOut1[:0])
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// hash output -> scalar
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// Take 64 byte output from keccak512 so need to set bytes as long
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r, err := edwards25519.NewScalar().SetUniformBytes(hOut1[:])
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if err != nil {
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return err
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}
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// R = r*G
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R := edwards25519.Point{}
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R.ScalarBaseMult(r)
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RBytes := R.Bytes()
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// s = H(R + pubkey + msg)
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hEngine.Reset()
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_, err = hEngine.Write(RBytes)
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if err != nil {
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return err
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}
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_, err = hEngine.Write(privateKey[32:])
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if err != nil {
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return err
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}
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_, err = hEngine.Write(message)
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if err != nil {
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return err
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}
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var hOut2 [64]byte
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hEngine.Sum(hOut2[:0])
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// hash output -> scalar
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// Take 64 byte output from keccak512 so need to set bytes as long
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h, err := edwards25519.NewScalar().SetUniformBytes(hOut2[:])
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if err != nil {
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return err
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}
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// s = (r + h * privKey)
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s := edwards25519.NewScalar().MultiplyAdd(h, sc, r)
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copy(signature[:], RBytes)
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copy(signature[32:], s.Bytes())
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return nil
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}
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// Verify reports whether sig is a valid signature of message by publicKey. It
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// will panic if len(publicKey) is not PublicKeySize.
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// Previously publicKey is of type PublicKey
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func Verify(publicKey PublicKey, message, sig []byte) (bool, error) {
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if l := len(publicKey); l != PublicKeySize {
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return false, fmt.Errorf("ed25519: bad public key length: " + strconv.Itoa(l))
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}
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if len(sig) != SignatureSize || sig[63]&224 != 0 {
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return false, fmt.Errorf("ed25519: bad signature size: " + strconv.Itoa(len(sig)))
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}
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RBytes := sig[:32]
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sBytes := sig[32:]
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var publicKeyBytes [32]byte
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copy(publicKeyBytes[:], publicKey)
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A := edwards25519.Point{}
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_, err := A.SetBytes(publicKeyBytes[:])
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if err != nil {
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return false, err
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}
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negA := edwards25519.Point{}
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negA.Negate(&A)
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// h = H(R + pubkey + msg)
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hEngine := sha3.NewLegacyKeccak512()
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_, err = hEngine.Write(RBytes)
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if err != nil {
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return false, err
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}
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_, err = hEngine.Write(publicKeyBytes[:])
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if err != nil {
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return false, err
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}
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_, err = hEngine.Write(message)
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if err != nil {
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return false, err
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}
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var hOut1 [64]byte
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hEngine.Sum(hOut1[:0])
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// hash output -> scalar
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// Take 64 byte output from keccak512 so need to set bytes as long
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h, err := edwards25519.NewScalar().SetUniformBytes(hOut1[:])
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if err != nil {
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return false, err
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}
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// s was generated in sign so can set as canonical
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s, err := edwards25519.NewScalar().SetCanonicalBytes(sBytes)
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if err != nil {
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return false, err
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}
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// R' = s*G - h*Pubkey = h*negPubkey + s*G
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RPrime := edwards25519.Point{}
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RPrime.VarTimeDoubleScalarBaseMult(h, &negA, s)
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RPrimeBytes := RPrime.Bytes()
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// Check R == R'
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return bytes.Equal(RBytes, RPrimeBytes), nil
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}
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