create RNG in token module

common/token/token.go

@@ -1,13 +1,22 @@
 package token
 
-import "math/rand"
+import (
+	"math/rand"
+	"time"
+)
 
 // Generate returns an alphanumeric token of specified length
 func Generate(length int) string {
+	rng := RNG()
 	var chars = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
 	b := make([]rune, length)
 	for i := range b {
-		b[i] = chars[rand.Intn(len(chars))]
+		b[i] = chars[rng.Intn(len(chars))]
 	}
 	return string(b)
 }
+
+// RNG returns a new RNG generator
+func RNG() *rand.Rand {
+	return rand.New(rand.NewSource(time.Now().UnixNano()))
+}