Set both key generation and ECDSA nonce to use mixed entropy

* Move random entropy functions to new package randentropy
* Add function to get n bytes entropy where up to first 32
  bytes are mixed with OS entropy sources

4 files changed, 92 insertions, 18 deletions

diff --git a/crypto/key_store_passphrase.go b/crypto/key_store_passphrase.go
index 0862b7886..74408f874 100644
--- a/crypto/key_store_passphrase.go
+++ b/crypto/key_store_passphrase.go
@@ -68,10 +68,10 @@ import (
 	"code.google.com/p/go.crypto/scrypt"
 	"crypto/aes"
 	"crypto/cipher"
-	crand "crypto/rand"
 	"encoding/hex"
 	"encoding/json"
 	"errors"
+	"github.com/ethereum/go-ethereum/crypto/randentropy"
 	"io"
 	"os"
 	"path"
@@ -116,7 +116,7 @@ func (ks keyStorePassphrase) GetKeyAddresses() (addresses [][]byte, err error) {
 
 func (ks keyStorePassphrase) StoreKey(key *Key, auth string) (err error) {
 	authArray := []byte(auth)
-	salt := GetEntropyCSPRNG(32)
+	salt := randentropy.GetEntropyMixed(32)
 	derivedKey, err := scrypt.Key(authArray, salt, scryptN, scryptr, scryptp, scryptdkLen)
 	if err != nil {
 		return err
@@ -131,7 +131,7 @@ func (ks keyStorePassphrase) StoreKey(key *Key, auth string) (err error) {
 		return err
 	}
 
-	iv := GetEntropyCSPRNG(aes.BlockSize) // 16
+	iv := randentropy.GetEntropyMixed(aes.BlockSize) // 16
 	AES256CBCEncrypter := cipher.NewCBCEncrypter(AES256Block, iv)
 	cipherText := make([]byte, len(toEncrypt))
 	AES256CBCEncrypter.CryptBlocks(cipherText, toEncrypt)
@@ -196,12 +196,3 @@ func DecryptKey(ks keyStorePassphrase, keyAddr []byte, auth string) (keyBytes []
 	}
 	return keyBytes, keyId, err
 }
-
-func GetEntropyCSPRNG(n int) []byte {
-	mainBuff := make([]byte, n)
-	_, err := io.ReadFull(crand.Reader, mainBuff)
-	if err != nil {
-		panic("key generation: reading from crypto/rand failed: " + err.Error())
-	}
-	return mainBuff
-}
diff --git a/crypto/key_store_test.go b/crypto/key_store_test.go
index 0d229ab65..a136ba992 100644
--- a/crypto/key_store_test.go
+++ b/crypto/key_store_test.go
@@ -1,7 +1,7 @@
 package crypto
 
 import (
-	crand "crypto/rand"
+	"github.com/ethereum/go-ethereum/crypto/randentropy"
 	"reflect"
 	"testing"
 )
@@ -9,7 +9,7 @@ import (
 func TestKeyStorePlain(t *testing.T) {
 	ks := NewKeyStorePlain(DefaultDataDir())
 	pass := "" // not used but required by API
-	k1, err := ks.GenerateNewKey(crand.Reader, pass)
+	k1, err := ks.GenerateNewKey(new(randentropy.RandEntropy), pass)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -37,7 +37,7 @@ func TestKeyStorePlain(t *testing.T) {
 func TestKeyStorePassphrase(t *testing.T) {
 	ks := NewKeyStorePassphrase(DefaultDataDir())
 	pass := "foo"
-	k1, err := ks.GenerateNewKey(crand.Reader, pass)
+	k1, err := ks.GenerateNewKey(new(randentropy.RandEntropy), pass)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -63,7 +63,7 @@ func TestKeyStorePassphrase(t *testing.T) {
 func TestKeyStorePassphraseDecryptionFail(t *testing.T) {
 	ks := NewKeyStorePassphrase(DefaultDataDir())
 	pass := "foo"
-	k1, err := ks.GenerateNewKey(crand.Reader, pass)
+	k1, err := ks.GenerateNewKey(new(randentropy.RandEntropy), pass)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/crypto/randentropy/rand_entropy.go b/crypto/randentropy/rand_entropy.go
new file mode 100644
index 000000000..28181030c
--- /dev/null
+++ b/crypto/randentropy/rand_entropy.go
@@ -0,0 +1,82 @@
+package randentropy
+
+import (
+	crand "crypto/rand"
+	"encoding/binary"
+	"github.com/ethereum/go-ethereum/crypto/sha3"
+	"io"
+	"os"
+	"strings"
+	"time"
+)
+
+type RandEntropy struct {
+}
+
+func (*RandEntropy) Read(bytes []byte) (n int, err error) {
+	readBytes := GetEntropyMixed(len(bytes))
+	copy(bytes, readBytes)
+	return len(bytes), nil
+}
+
+// TODO: copied from crypto.go , move to sha3 package?
+func Sha3(data []byte) []byte {
+	d := sha3.NewKeccak256()
+	d.Write(data)
+
+	return d.Sum(nil)
+}
+
+// TODO: verify. this needs to be audited
+// we start with crypt/rand, then XOR in additional entropy from OS
+func GetEntropyMixed(n int) []byte {
+	startTime := time.Now().UnixNano()
+	// for each source, we take SHA3 of the source and use it as seed to math/rand
+	// then read bytes from it and XOR them onto the bytes read from crypto/rand
+	mainBuff := GetEntropyCSPRNG(n)
+	// 1. OS entropy sources
+	startTimeBytes := make([]byte, 32)
+	binary.PutVarint(startTimeBytes, startTime)
+	startTimeHash := Sha3(startTimeBytes)
+	mixBytes(mainBuff, startTimeHash)
+
+	pid := os.Getpid()
+	pidBytes := make([]byte, 32)
+	binary.PutUvarint(pidBytes, uint64(pid))
+	pidHash := Sha3(pidBytes)
+	mixBytes(mainBuff, pidHash)
+
+	osEnv := os.Environ()
+	osEnvBytes := []byte(strings.Join(osEnv, ""))
+	osEnvHash := Sha3(osEnvBytes)
+	mixBytes(mainBuff, osEnvHash)
+
+	// not all OS have hostname in env variables
+	osHostName, err := os.Hostname()
+	if err != nil {
+		osHostNameBytes := []byte(osHostName)
+		osHostNameHash := Sha3(osHostNameBytes)
+		mixBytes(mainBuff, osHostNameHash)
+	}
+	return mainBuff
+}
+
+func GetEntropyCSPRNG(n int) []byte {
+	mainBuff := make([]byte, n)
+	_, err := io.ReadFull(crand.Reader, mainBuff)
+	if err != nil {
+		panic("reading from crypto/rand failed: " + err.Error())
+	}
+	return mainBuff
+}
+
+func mixBytes(buff []byte, mixBuff []byte) []byte {
+	bytesToMix := len(buff)
+	if bytesToMix > 32 {
+		bytesToMix = 32
+	}
+	for i := 0; i < bytesToMix; i++ {
+		buff[i] ^= mixBuff[i]
+	}
+	return buff
+}
diff --git a/crypto/secp256k1/secp256.go b/crypto/secp256k1/secp256.go
index c01598b84..c1e37629e 100644
--- a/crypto/secp256k1/secp256.go
+++ b/crypto/secp256k1/secp256.go
@@ -15,6 +15,7 @@ import "C"
 import (
 	"bytes"
 	"errors"
+	"github.com/ethereum/go-ethereum/crypto/randentropy"
 	"unsafe"
 )
 
@@ -68,7 +69,7 @@ func GenerateKeyPair() ([]byte, []byte) {
 	const seckey_len = 32
 
 	var pubkey []byte = make([]byte, pubkey_len)
-	var seckey []byte = RandByte(seckey_len)
+	var seckey []byte = randentropy.GetEntropyMixed(seckey_len)
 
 	var pubkey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&pubkey[0]))
 	var seckey_ptr *C.uchar = (*C.uchar)(unsafe.Pointer(&seckey[0]))
@@ -124,7 +125,7 @@ int secp256k1_ecdsa_sign_compact(const unsigned char *msg, int msglen,
 */
 
 func Sign(msg []byte, seckey []byte) ([]byte, error) {
-	nonce := RandByte(32)
+	nonce := randentropy.GetEntropyMixed(32)
 
 	var sig []byte = make([]byte, 65)
 	var recid C.int