whisper: key generation updated

whisper/whisperv5/message.go

@@ -130,7 +130,7 @@ func (msg *SentMessage) appendPadding(params *MessageParams) {
 			panic("please fix the padding algorithm before releasing new version")
 		}
 		buf := make([]byte, padSize)
-		randomize(buf[1:]) // change to: err = mrand.Read(buf[1:])
+		randomize(buf[1:])
 		buf[0] = byte(padSize)
 		if params.Padding != nil {
 			copy(buf[1:], params.Padding)
@@ -208,7 +208,10 @@ func (msg *SentMessage) encryptSymmetric(key []byte) (salt []byte, nonce []byte,
 	_, err = crand.Read(nonce)
 	if err != nil {
 		return nil, nil, err
+	} else if !validateSymmetricKey(nonce) {
+		return nil, nil, errors.New("crypto/rand failed to generate nonce")
 	}
+
 	msg.Raw = aesgcm.Seal(nil, nonce, msg.Raw, nil)
 	return salt, nonce, nil
 }

whisper/whisperv5/whisper.go

@@ -22,6 +22,7 @@ import (
 	crand "crypto/rand"
 	"crypto/sha256"
 	"fmt"
+	mrand "math/rand"
 	"sync"
 	"time"
 
@@ -82,6 +83,9 @@ func NewWhisper(server MailServer) *Whisper {
 		Run:     whisper.HandlePeer,
 	}
 
+	seed := time.Now().Unix()
+	mrand.Seed(seed)
+
 	return whisper
 }
 
@@ -177,12 +181,23 @@ func (w *Whisper) GetIdentity(pubKey string) *ecdsa.PrivateKey {
 }
 
 func (w *Whisper) GenerateSymKey(name string) error {
-	buf := make([]byte, aesKeyLength*2)
+	const size = aesKeyLength * 2
-	_, err := crand.Read(buf) // todo: check how safe is this function
+	buf := make([]byte, size)
+	buf2 := make([]byte, size)
+	_, err := crand.Read(buf)
 	if err != nil {
 		return err
 	} else if !validateSymmetricKey(buf) {
-		return fmt.Errorf("crypto/rand failed to generate random data")
+		return fmt.Errorf("error in GenerateSymKey: crypto/rand failed to generate random data")
+	}
+
+	randomize(buf2)
+	if !validateSymmetricKey(buf2) {
+		return fmt.Errorf("error in GenerateSymKey: math/rand failed to generate random data")
+	}
+
+	for i := 0; i < size; i++ {
+		buf[i] ^= buf2[i]
 	}
 
 	key := buf[:aesKeyLength]