From aa73420207cba02a68befdbb8667f1e6ceed3f4d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?P=C3=A9ter=20Szil=C3=A1gyi?= <peterke@gmail.com>
Date: Tue, 23 May 2017 14:58:03 +0300
Subject: accounts/keystore, crypto: enforce 256 bit keys on import

---
 crypto/crypto.go | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

(limited to 'crypto/crypto.go')

diff --git a/crypto/crypto.go b/crypto/crypto.go
index 0b8c06008..d38ffd0d5 100644
--- a/crypto/crypto.go
+++ b/crypto/crypto.go
@@ -22,12 +22,14 @@ import (
 	"crypto/rand"
 	"encoding/hex"
 	"errors"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"math/big"
 	"os"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/math"
 	"github.com/ethereum/go-ethereum/crypto/sha3"
 	"github.com/ethereum/go-ethereum/rlp"
 )
@@ -76,23 +78,22 @@ func CreateAddress(b common.Address, nonce uint64) common.Address {
 }
 
 // ToECDSA creates a private key with the given D value.
-func ToECDSA(prv []byte) *ecdsa.PrivateKey {
-	if len(prv) == 0 {
-		return nil
-	}
-
+func ToECDSA(d []byte) (*ecdsa.PrivateKey, error) {
 	priv := new(ecdsa.PrivateKey)
 	priv.PublicKey.Curve = S256()
-	priv.D = new(big.Int).SetBytes(prv)
-	priv.PublicKey.X, priv.PublicKey.Y = priv.PublicKey.Curve.ScalarBaseMult(prv)
-	return priv
+	if 8*len(d) != priv.Params().BitSize {
+		return nil, fmt.Errorf("invalid length, need %d bits", priv.Params().BitSize)
+	}
+	priv.D = new(big.Int).SetBytes(d)
+	priv.PublicKey.X, priv.PublicKey.Y = priv.PublicKey.Curve.ScalarBaseMult(d)
+	return priv, nil
 }
 
 func FromECDSA(prv *ecdsa.PrivateKey) []byte {
 	if prv == nil {
 		return nil
 	}
-	return prv.D.Bytes()
+	return math.PaddedBigBytes(prv.D, 32)
 }
 
 func ToECDSAPub(pub []byte) *ecdsa.PublicKey {
@@ -116,10 +117,7 @@ func HexToECDSA(hexkey string) (*ecdsa.PrivateKey, error) {
 	if err != nil {
 		return nil, errors.New("invalid hex string")
 	}
-	if len(b) != 32 {
-		return nil, errors.New("invalid length, need 256 bits")
-	}
-	return ToECDSA(b), nil
+	return ToECDSA(b)
 }
 
 // LoadECDSA loads a secp256k1 private key from the given file.
@@ -139,8 +137,7 @@ func LoadECDSA(file string) (*ecdsa.PrivateKey, error) {
 	if err != nil {
 		return nil, err
 	}
-
-	return ToECDSA(key), nil
+	return ToECDSA(key)
 }
 
 // SaveECDSA saves a secp256k1 private key to the given file with
-- 
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