trie, whisper/whisperv5: use math/rand Read function

whisper/whisperv5/message.go

@@ -128,7 +128,7 @@ func (msg *SentMessage) appendPadding(params *MessageParams) {
 			panic("please fix the padding algorithm before releasing new version")
 		}
 		buf := make([]byte, padSize)
-		randomize(buf[1:])
+		mrand.Read(buf[1:])
 		buf[0] = byte(padSize)
 		if params.Padding != nil {
 			copy(buf[1:], params.Padding)
@@ -365,19 +365,3 @@ func (msg *ReceivedMessage) hash() []byte {
 	}
 	return crypto.Keccak256(msg.Raw)
 }
-
-// rand.Rand provides a Read method in Go 1.7 and later,
-// but we can't use it yet.
-func randomize(b []byte) {
-	cnt := 0
-	val := mrand.Int63()
-	for n := 0; n < len(b); n++ {
-		b[n] = byte(val)
-		val >>= 8
-		cnt++
-		if cnt >= 7 {
-			cnt = 0
-			val = mrand.Int63()
-		}
-	}
-}