diff --git a/shadowsocks/obfsplugin/auth.py b/shadowsocks/obfsplugin/auth.py
index 82031dd..5c88a29 100755
--- a/shadowsocks/obfsplugin/auth.py
+++ b/shadowsocks/obfsplugin/auth.py
@@ -37,6 +37,9 @@ from shadowsocks import common, lru_cache, encrypt
 from shadowsocks.obfsplugin import plain
 from shadowsocks.common import to_bytes, to_str, ord, chr
 
+def create_auth_simple(method):
+    return auth_simple(method)
+
 def create_auth_sha1(method):
     return auth_sha1(method)
 
@@ -56,6 +59,7 @@ def create_auth_aes128_sha1(method):
     return auth_aes128_sha1(method, hashlib.sha1)
 
 obfs_map = {
+        'auth_simple': (create_auth_simple,),
         'auth_sha1': (create_auth_sha1,),
         'auth_sha1_compatible': (create_auth_sha1,),
         'auth_sha1_v2': (create_auth_sha1_v2,),
@@ -207,6 +211,162 @@ class obfs_auth_data(object):
         else:
             return self.client_id[client_id].insert(connection_id)
 
+class auth_simple(auth_base):
+    def __init__(self, method):
+        super(auth_simple, self).__init__(method)
+        self.recv_buf = b''
+        self.unit_len = 8100
+        self.decrypt_packet_num = 0
+        self.raw_trans = False
+        self.has_sent_header = False
+        self.has_recv_header = False
+        self.client_id = 0
+        self.connection_id = 0
+        self.max_time_dif = 60 * 5 # time dif (second) setting
+
+    def init_data(self):
+        return obfs_auth_data()
+
+    def set_server_info(self, server_info):
+        self.server_info = server_info
+        try:
+            max_client = int(server_info.protocol_param)
+        except:
+            max_client = 16
+        self.server_info.data.set_max_client(max_client)
+
+    def pack_data(self, buf):
+        rnd_data = os.urandom(common.ord(os.urandom(1)[0]) % 16)
+        data = common.chr(len(rnd_data) + 1) + rnd_data + buf
+        data = struct.pack('>H', len(data) + 6) + data
+        crc = (0xffffffff - binascii.crc32(data)) & 0xffffffff
+        data += struct.pack('<I', crc)
+        return data
+
+    def auth_data(self):
+        utc_time = int(time.time()) & 0xFFFFFFFF
+        if self.server_info.data.connection_id > 0xFF000000:
+            self.server_info.data.local_client_id = b''
+        if not self.server_info.data.local_client_id:
+            self.server_info.data.local_client_id = os.urandom(4)
+            logging.debug("local_client_id %s" % (binascii.hexlify(self.server_info.data.local_client_id),))
+            self.server_info.data.connection_id = struct.unpack('<I', os.urandom(4))[0] & 0xFFFFFF
+        self.server_info.data.connection_id += 1
+        return b''.join([struct.pack('<I', utc_time),
+                self.server_info.data.local_client_id,
+                struct.pack('<I', self.server_info.data.connection_id)])
+
+    def client_pre_encrypt(self, buf):
+        ret = b''
+        if not self.has_sent_header:
+            head_size = self.get_head_size(buf, 30)
+            datalen = min(len(buf), random.randint(0, 31) + head_size)
+            ret += self.pack_data(self.auth_data() + buf[:datalen])
+            buf = buf[datalen:]
+            self.has_sent_header = True
+        while len(buf) > self.unit_len:
+            ret += self.pack_data(buf[:self.unit_len])
+            buf = buf[self.unit_len:]
+        ret += self.pack_data(buf)
+        return ret
+
+    def client_post_decrypt(self, buf):
+        if self.raw_trans:
+            return buf
+        self.recv_buf += buf
+        out_buf = b''
+        while len(self.recv_buf) > 2:
+            length = struct.unpack('>H', self.recv_buf[:2])[0]
+            if length >= 8192 or length < 7:
+                self.raw_trans = True
+                self.recv_buf = b''
+                raise Exception('client_post_decrypt data error')
+            if length > len(self.recv_buf):
+                break
+
+            if (binascii.crc32(self.recv_buf[:length]) & 0xffffffff) != 0xffffffff:
+                self.raw_trans = True
+                self.recv_buf = b''
+                raise Exception('client_post_decrypt data uncorrect CRC32')
+
+            pos = common.ord(self.recv_buf[2]) + 2
+            out_buf += self.recv_buf[pos:length - 4]
+            self.recv_buf = self.recv_buf[length:]
+
+        if out_buf:
+            self.decrypt_packet_num += 1
+        return out_buf
+
+    def server_pre_encrypt(self, buf):
+        ret = b''
+        while len(buf) > self.unit_len:
+            ret += self.pack_data(buf[:self.unit_len])
+            buf = buf[self.unit_len:]
+        ret += self.pack_data(buf)
+        return ret
+
+    def server_post_decrypt(self, buf):
+        if self.raw_trans:
+            return (buf, False)
+        self.recv_buf += buf
+        out_buf = b''
+        while len(self.recv_buf) > 2:
+            length = struct.unpack('>H', self.recv_buf[:2])[0]
+            if length >= 8192 or length < 7:
+                self.raw_trans = True
+                self.recv_buf = b''
+                if self.decrypt_packet_num == 0:
+                    logging.info('auth_simple: over size')
+                    return (b'E', False)
+                else:
+                    raise Exception('server_post_decrype data error')
+            if length > len(self.recv_buf):
+                break
+
+            if (binascii.crc32(self.recv_buf[:length]) & 0xffffffff) != 0xffffffff:
+                logging.info('auth_simple: crc32 error, data %s' % (binascii.hexlify(self.recv_buf[:length]),))
+                self.raw_trans = True
+                self.recv_buf = b''
+                if self.decrypt_packet_num == 0:
+                    return (b'E', False)
+                else:
+                    raise Exception('server_post_decrype data uncorrect CRC32')
+
+            pos = common.ord(self.recv_buf[2]) + 2
+            out_buf += self.recv_buf[pos:length - 4]
+            if not self.has_recv_header:
+                if len(out_buf) < 12:
+                    self.raw_trans = True
+                    self.recv_buf = b''
+                    logging.info('auth_simple: too short')
+                    return (b'E', False)
+                utc_time = struct.unpack('<I', out_buf[:4])[0]
+                client_id = struct.unpack('<I', out_buf[4:8])[0]
+                connection_id = struct.unpack('<I', out_buf[8:12])[0]
+                time_dif = common.int32((int(time.time()) & 0xffffffff) - utc_time)
+                if time_dif < -self.max_time_dif or time_dif > self.max_time_dif \
+                        or common.int32(utc_time - self.server_info.data.startup_time) < 0:
+                    self.raw_trans = True
+                    self.recv_buf = b''
+                    logging.info('auth_simple: wrong timestamp, time_dif %d, data %s' % (time_dif, binascii.hexlify(out_buf),))
+                    return (b'E', False)
+                elif self.server_info.data.insert(client_id, connection_id):
+                    self.has_recv_header = True
+                    out_buf = out_buf[12:]
+                    self.client_id = client_id
+                    self.connection_id = connection_id
+                else:
+                    self.raw_trans = True
+                    self.recv_buf = b''
+                    logging.info('auth_simple: auth fail, data %s' % (binascii.hexlify(out_buf),))
+                    return (b'E', False)
+            self.recv_buf = self.recv_buf[length:]
+
+        if out_buf:
+            self.server_info.data.update(self.client_id, self.connection_id)
+            self.decrypt_packet_num += 1
+        return (out_buf, False)
+
 class auth_sha1(auth_base):
     def __init__(self, method):
         super(auth_sha1, self).__init__(method)