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ed25519: drop Go 1.12 compatibility
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x/crypto/ed25519 moved to the standard library in Go 1.13. This change
drops the compatibility wrapper we were keeping around to make Go 1.12
and earlier work.

Change-Id: I860ed963a0660753d01c89014c21360b239a38ac
Reviewed-on: https://go-review.googlesource.com/c/crypto/+/317169
Trust: Filippo Valsorda <[email protected]>
Run-TryBot: Filippo Valsorda <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Katie Hockman <[email protected]>
Trust: Katie Hockman <[email protected]>
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@FiloSottile
FiloSottile committed Feb 8, 2022
1 parent 30dcbda commit 20e1d8d
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188 changes: 18 additions & 170 deletions ed25519/ed25519.go
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Original file line number Diff line number Diff line change
@@ -1,13 +1,7 @@
// Copyright 2016 The Go Authors. All rights reserved.
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// In Go 1.13, the ed25519 package was promoted to the standard library as
// crypto/ed25519, and this package became a wrapper for the standard library one.
//
//go:build !go1.13
// +build !go1.13

// Package ed25519 implements the Ed25519 signature algorithm. See
// https://ed25519.cr.yp.to/.
//
Expand All @@ -16,21 +10,15 @@
// representation includes a public key suffix to make multiple signing
// operations with the same key more efficient. This package refers to the RFC
// 8032 private key as the “seed”.
//
// Beginning with Go 1.13, the functionality of this package was moved to the
// standard library as crypto/ed25519. This package only acts as a compatibility
// wrapper.
package ed25519

// This code is a port of the public domain, “ref10” implementation of ed25519
// from SUPERCOP.

import (
"bytes"
"crypto"
cryptorand "crypto/rand"
"crypto/sha512"
"errors"
"crypto/ed25519"
"io"
"strconv"

"golang.org/x/crypto/ed25519/internal/edwards25519"
)

const (
Expand All @@ -45,179 +33,39 @@ const (
)

// PublicKey is the type of Ed25519 public keys.
type PublicKey []byte
//
// This type is an alias for crypto/ed25519's PublicKey type.
// See the crypto/ed25519 package for the methods on this type.
type PublicKey = ed25519.PublicKey

// PrivateKey is the type of Ed25519 private keys. It implements crypto.Signer.
type PrivateKey []byte

// Public returns the PublicKey corresponding to priv.
func (priv PrivateKey) Public() crypto.PublicKey {
publicKey := make([]byte, PublicKeySize)
copy(publicKey, priv[32:])
return PublicKey(publicKey)
}

// Seed returns the private key seed corresponding to priv. It is provided for
// interoperability with RFC 8032. RFC 8032's private keys correspond to seeds
// in this package.
func (priv PrivateKey) Seed() []byte {
seed := make([]byte, SeedSize)
copy(seed, priv[:32])
return seed
}

// Sign signs the given message with priv.
// Ed25519 performs two passes over messages to be signed and therefore cannot
// handle pre-hashed messages. Thus opts.HashFunc() must return zero to
// indicate the message hasn't been hashed. This can be achieved by passing
// crypto.Hash(0) as the value for opts.
func (priv PrivateKey) Sign(rand io.Reader, message []byte, opts crypto.SignerOpts) (signature []byte, err error) {
if opts.HashFunc() != crypto.Hash(0) {
return nil, errors.New("ed25519: cannot sign hashed message")
}

return Sign(priv, message), nil
}
//
// This type is an alias for crypto/ed25519's PrivateKey type.
// See the crypto/ed25519 package for the methods on this type.
type PrivateKey = ed25519.PrivateKey

// GenerateKey generates a public/private key pair using entropy from rand.
// If rand is nil, crypto/rand.Reader will be used.
func GenerateKey(rand io.Reader) (PublicKey, PrivateKey, error) {
if rand == nil {
rand = cryptorand.Reader
}

seed := make([]byte, SeedSize)
if _, err := io.ReadFull(rand, seed); err != nil {
return nil, nil, err
}

privateKey := NewKeyFromSeed(seed)
publicKey := make([]byte, PublicKeySize)
copy(publicKey, privateKey[32:])

return publicKey, privateKey, nil
return ed25519.GenerateKey(rand)
}

// NewKeyFromSeed calculates a private key from a seed. It will panic if
// len(seed) is not SeedSize. This function is provided for interoperability
// with RFC 8032. RFC 8032's private keys correspond to seeds in this
// package.
func NewKeyFromSeed(seed []byte) PrivateKey {
if l := len(seed); l != SeedSize {
panic("ed25519: bad seed length: " + strconv.Itoa(l))
}

digest := sha512.Sum512(seed)
digest[0] &= 248
digest[31] &= 127
digest[31] |= 64

var A edwards25519.ExtendedGroupElement
var hBytes [32]byte
copy(hBytes[:], digest[:])
edwards25519.GeScalarMultBase(&A, &hBytes)
var publicKeyBytes [32]byte
A.ToBytes(&publicKeyBytes)

privateKey := make([]byte, PrivateKeySize)
copy(privateKey, seed)
copy(privateKey[32:], publicKeyBytes[:])

return privateKey
return ed25519.NewKeyFromSeed(seed)
}

// Sign signs the message with privateKey and returns a signature. It will
// panic if len(privateKey) is not PrivateKeySize.
func Sign(privateKey PrivateKey, message []byte) []byte {
if l := len(privateKey); l != PrivateKeySize {
panic("ed25519: bad private key length: " + strconv.Itoa(l))
}

h := sha512.New()
h.Write(privateKey[:32])

var digest1, messageDigest, hramDigest [64]byte
var expandedSecretKey [32]byte
h.Sum(digest1[:0])
copy(expandedSecretKey[:], digest1[:])
expandedSecretKey[0] &= 248
expandedSecretKey[31] &= 63
expandedSecretKey[31] |= 64

h.Reset()
h.Write(digest1[32:])
h.Write(message)
h.Sum(messageDigest[:0])

var messageDigestReduced [32]byte
edwards25519.ScReduce(&messageDigestReduced, &messageDigest)
var R edwards25519.ExtendedGroupElement
edwards25519.GeScalarMultBase(&R, &messageDigestReduced)

var encodedR [32]byte
R.ToBytes(&encodedR)

h.Reset()
h.Write(encodedR[:])
h.Write(privateKey[32:])
h.Write(message)
h.Sum(hramDigest[:0])
var hramDigestReduced [32]byte
edwards25519.ScReduce(&hramDigestReduced, &hramDigest)

var s [32]byte
edwards25519.ScMulAdd(&s, &hramDigestReduced, &expandedSecretKey, &messageDigestReduced)

signature := make([]byte, SignatureSize)
copy(signature[:], encodedR[:])
copy(signature[32:], s[:])

return signature
return ed25519.Sign(privateKey, message)
}

// Verify reports whether sig is a valid signature of message by publicKey. It
// will panic if len(publicKey) is not PublicKeySize.
func Verify(publicKey PublicKey, message, sig []byte) bool {
if l := len(publicKey); l != PublicKeySize {
panic("ed25519: bad public key length: " + strconv.Itoa(l))
}

if len(sig) != SignatureSize || sig[63]&224 != 0 {
return false
}

var A edwards25519.ExtendedGroupElement
var publicKeyBytes [32]byte
copy(publicKeyBytes[:], publicKey)
if !A.FromBytes(&publicKeyBytes) {
return false
}
edwards25519.FeNeg(&A.X, &A.X)
edwards25519.FeNeg(&A.T, &A.T)

h := sha512.New()
h.Write(sig[:32])
h.Write(publicKey[:])
h.Write(message)
var digest [64]byte
h.Sum(digest[:0])

var hReduced [32]byte
edwards25519.ScReduce(&hReduced, &digest)

var R edwards25519.ProjectiveGroupElement
var s [32]byte
copy(s[:], sig[32:])

// https://tools.ietf.org/html/rfc8032#section-5.1.7 requires that s be in
// the range [0, order) in order to prevent signature malleability.
if !edwards25519.ScMinimal(&s) {
return false
}

edwards25519.GeDoubleScalarMultVartime(&R, &hReduced, &A, &s)

var checkR [32]byte
R.ToBytes(&checkR)
return bytes.Equal(sig[:32], checkR[:])
return ed25519.Verify(publicKey, message, sig)
}
74 changes: 0 additions & 74 deletions ed25519/ed25519_go113.go
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