diff --git a/ate/utils.py b/ate/utils.py
index 6004f55b..de99935f 100644
--- a/ate/utils.py
+++ b/ate/utils.py
@@ -1,8 +1,22 @@
+import hashlib
 import json
-import yaml
 import os.path
+import random
+import string
+
+import yaml
+
 from ate.exception import ParamsError
 
+
+def gen_random_string(str_len):
+    return ''.join(
+        random.choice(string.ascii_letters + string.digits) for _ in range(str_len))
+
+def gen_md5(str_list):
+    authorization_str = "".join(str_list)
+    return hashlib.md5(authorization_str.encode('utf-8')).hexdigest()
+
 def load_yaml_file(yaml_file):
     with open(yaml_file, 'r+') as stream:
         return yaml.load(stream)
diff --git a/test/base.py b/test/base.py
index c02d5287..40376c83 100644
--- a/test/base.py
+++ b/test/base.py
@@ -1,10 +1,8 @@
-import hashlib
 import multiprocessing
-import random
-import string
 import time
 import unittest
 
+from ate import utils
 from . import api_server
 
 
@@ -29,11 +27,9 @@ class ApiServerUnittest(unittest.TestCase):
 
     def prepare_headers(self, data=""):
         token = api_server.TOKEN
-        random_str = ''.join(
-            random.choice(string.ascii_uppercase + string.digits) for _ in range(5))
+        random_str = utils.gen_random_string(5)
+        authorization = utils.gen_md5([token, data, random_str])
 
-        authorization_str = "".join([token, data, random_str])
-        authorization = hashlib.md5(authorization_str.encode('utf-8')).hexdigest()
         headers = {
             'authorization': authorization,
             'random': random_str