Use stdlib when possible

README.md

@@ -1,8 +1,6 @@
 # ed25519
 
-A drop-in replacement for `golang/crypto/ed25519` ([godoc](https://godoc.org/golang.org/x/crypto/ed25519),
-[github](https://github.com/golang/crypto/tree/master/ed25519))
- with additional functionality. Uses SHA-512 and ECDSA signing algorithm.
+A drop-in replacement for `crypto/ed25519` ([godoc](https://godoc.org/golang.org/x/crypto/ed25519), [github](https://github.com/golang/crypto/tree/master/ed25519)) with additional functionality. Uses SHA-512 and ECDSA signing algorithm.
 
 ## Motivation
 
@@ -14,7 +12,7 @@ In order to verify the validity of a given signature, the validator should posse
 import "github.com/spacemeshos/ed25519"
 ```
 
-Import package `ed25519` from `github.com/spacemeshos/ed25519` instead of `golang.org/x/crypto/ed25519`.
+Import package `ed25519` from `github.com/spacemeshos/ed25519` instead of `crypto/ed25519`.
 
 ## Sign2
 

ed25519.go

@@ -8,210 +8,54 @@
 // These functions are also compatible with the “Ed25519” function defined in
 // RFC 8032. However, unlike RFC 8032's formulation, this package's private key
 // 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”.
+// operations with the same key more efficient.
 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"
 	"io"
-	"strconv"
 
-	"github.com/spacemeshos/ed25519/internal/edwards25519"
+	"crypto/ed25519"
 )
 
 const (
 	// PublicKeySize is the size, in bytes, of public keys as used in this package.
-	PublicKeySize = 32
+	PublicKeySize = ed25519.PublicKeySize
 	// PrivateKeySize is the size, in bytes, of private keys as used in this package.
-	PrivateKeySize = 64
+	PrivateKeySize = ed25519.PrivateKeySize
 	// SignatureSize is the size, in bytes, of signatures generated and verified by this package.
-	SignatureSize = 64
+	SignatureSize = ed25519.SignatureSize
 	// SeedSize is the size, in bytes, of private key seeds. These are the private key representations used by RFC 8032.
-	SeedSize = 32
+	SeedSize = ed25519.SeedSize
 )
 
 // PublicKey is the type of Ed25519 public keys.
-type PublicKey []byte
+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
-}
+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)
 }

ed25519_ext.go

@@ -17,7 +17,6 @@ import (
 // Note that signature must be created using Sign2() and NOT using Sign().
 // It will panic if len(sig) is not SignatureSize.
 func ExtractPublicKey(message, sig []byte) (PublicKey, error) {
-
 	if l := len(sig); l != SignatureSize || sig[63]&224 != 0 {
 		return nil, errors.New("ed25519: bad signature format")
 	}