mirror of
https://source.quilibrium.com/quilibrium/ceremonyclient.git
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289 lines
7.6 KiB
Go
289 lines
7.6 KiB
Go
// Copyright 2016 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package ted25519 implements the Ed25519 signature algorithm. See 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 ted25519
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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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"crypto/sha512"
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"fmt"
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"io"
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"strconv"
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"source.quilibrium.com/quilibrium/monorepo/nekryptology/pkg/core/curves"
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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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// 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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digest := sha512.Sum512(seed)
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digest[0] &= 248
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digest[31] &= 127
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digest[31] |= 64
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var hBytes [32]byte
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copy(hBytes[:], digest[:])
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h, err := new(curves.ScalarEd25519).SetBytesClamping(hBytes[:])
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if err != nil {
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return err
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}
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ed25519 := curves.ED25519()
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A := ed25519.ScalarBaseMult(h)
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publicKeyBytes := A.ToAffineCompressed()
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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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var err error
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h := sha512.New()
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_, err = h.Write(privateKey[:32])
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if err != nil {
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return err
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}
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var digest1, messageDigest, hramDigest [64]byte
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var expandedSecretKey [32]byte
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_ = h.Sum(digest1[:0])
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copy(expandedSecretKey[:], digest1[:])
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expandedSecretKey[0] &= 248
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expandedSecretKey[31] &= 63
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expandedSecretKey[31] |= 64
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h.Reset()
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_, err = h.Write(digest1[32:])
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if err != nil {
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return err
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}
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_, _ = h.Write(message)
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if err != nil {
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return err
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}
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_ = h.Sum(messageDigest[:0])
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r, err := new(curves.ScalarEd25519).SetBytesWide(messageDigest[:])
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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 := curves.ED25519().Point.Generator().Mul(r)
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encodedR := R.ToAffineCompressed()
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h.Reset()
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_, err = h.Write(encodedR[:])
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if err != nil {
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return err
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}
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_, err = h.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 = h.Write(message)
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if err != nil {
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return err
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}
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_ = h.Sum(hramDigest[:0])
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// Set k and s
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k, err := new(curves.ScalarEd25519).SetBytesWide(hramDigest[:])
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if err != nil {
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return err
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}
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s, err := new(curves.ScalarEd25519).SetBytesClamping(expandedSecretKey[:])
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if err != nil {
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return err
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}
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// S = k*s + r
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S := k.MulAdd(s, r)
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copy(signature[:], encodedR[:])
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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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var publicKeyBytes [32]byte
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copy(publicKeyBytes[:], publicKey)
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A, err := new(curves.PointEd25519).FromAffineCompressed(publicKeyBytes[:])
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if err != nil {
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return false, err
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}
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// Negate sets A = -A, and returns A. It actually negates X and T but keep Y and Z
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negA := A.Neg()
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h := sha512.New()
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_, err = h.Write(sig[:32])
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if err != nil {
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panic(err)
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}
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_, err = h.Write(publicKey[:])
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if err != nil {
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return false, err
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}
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_, err = h.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 digest [64]byte
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_ = h.Sum(digest[:0])
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hReduced, err := new(curves.ScalarEd25519).SetBytesWide(digest[:])
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if err != nil {
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return false, err
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}
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var s [32]byte
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copy(s[:], sig[32:])
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sScalar, err := new(curves.ScalarEd25519).SetBytesCanonical(s[:])
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if err != nil {
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return false, err
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}
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// R' = hash * A + s * BasePoint
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R := new(curves.PointEd25519).VarTimeDoubleScalarBaseMult(hReduced, negA, sScalar)
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// Check R == R'
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return bytes.Equal(sig[:32], R.ToAffineCompressed()), nil
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}
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