diff --git a/setup.py b/setup.py
index e6a7ff7..ba61ad3 100644
--- a/setup.py
+++ b/setup.py
@@ -7,7 +7,7 @@ with codecs.open('README.rst', encoding='utf-8') as f:
 
 setup(
     name="shadowsocks",
-    version="2.8.2",
+    version="2.9.0",
     license='http://www.apache.org/licenses/LICENSE-2.0',
     description="A fast tunnel proxy that help you get through firewalls",
     author='clowwindy',
diff --git a/shadowsocks/crypto/sodium.py b/shadowsocks/crypto/sodium.py
index ae86fef..6caea02 100644
--- a/shadowsocks/crypto/sodium.py
+++ b/shadowsocks/crypto/sodium.py
@@ -29,7 +29,7 @@ loaded = False
 
 buf_size = 2048
 
-# for salsa20 and chacha20
+# for salsa20 and chacha20 and chacha20-ietf
 BLOCK_SIZE = 64
 
 
@@ -51,6 +51,11 @@ def load_libsodium():
                                                         c_ulonglong,
                                                         c_char_p, c_ulonglong,
                                                         c_char_p)
+    libsodium.crypto_stream_chacha20_ietf_xor_ic.restype = c_int
+    libsodium.crypto_stream_chacha20_ietf_xor_ic.argtypes = (c_void_p, c_char_p,
+                                                        c_ulonglong,
+                                                        c_char_p, c_ulong,
+                                                        c_char_p)
 
     buf = create_string_buffer(buf_size)
     loaded = True
@@ -68,6 +73,8 @@ class SodiumCrypto(object):
             self.cipher = libsodium.crypto_stream_salsa20_xor_ic
         elif cipher_name == 'chacha20':
             self.cipher = libsodium.crypto_stream_chacha20_xor_ic
+        elif cipher_name == 'chacha20-ietf':
+            self.cipher = libsodium.crypto_stream_chacha20_ietf_xor_ic
         else:
             raise Exception('Unknown cipher')
         # byte counter, not block counter
@@ -97,6 +104,7 @@ class SodiumCrypto(object):
 ciphers = {
     'salsa20': (32, 8, SodiumCrypto),
     'chacha20': (32, 8, SodiumCrypto),
+    'chacha20-ietf': (32, 12, SodiumCrypto),
 }
 
 
@@ -115,6 +123,15 @@ def test_chacha20():
     util.run_cipher(cipher, decipher)
 
 
+def test_chacha20_ietf():
+
+    cipher = SodiumCrypto('chacha20-ietf', b'k' * 32, b'i' * 16, 1)
+    decipher = SodiumCrypto('chacha20-ietf', b'k' * 32, b'i' * 16, 0)
+
+    util.run_cipher(cipher, decipher)
+
+
 if __name__ == '__main__':
+    test_chacha20_ietf()
     test_chacha20()
     test_salsa20()