diff --git a/shadowsocks-csharp/Encryption/MbedTLS.cs b/shadowsocks-csharp/Encryption/MbedTLS.cs
index d29b26e5..01f8fd37 100644
--- a/shadowsocks-csharp/Encryption/MbedTLS.cs
+++ b/shadowsocks-csharp/Encryption/MbedTLS.cs
@@ -51,7 +51,7 @@ namespace Shadowsocks.Encryption
         [DllImport(DLLNAME, CallingConvention = CallingConvention.Cdecl)]
         public static extern int cipher_setup(IntPtr ctx, IntPtr cipher_info);
 
-        // check operation
+        // XXX: Check operation before using it
         [DllImport(DLLNAME, CallingConvention = CallingConvention.Cdecl)]
         public static extern int cipher_setkey(IntPtr ctx, byte[] key, int key_bitlen, int operation);
 
@@ -70,9 +70,6 @@ namespace Shadowsocks.Encryption
         [DllImport(DLLNAME, CallingConvention = CallingConvention.Cdecl)]
         public static extern void md5(byte[] input, uint ilen, byte[] output);
 
-        [DllImport(DLLNAME, CallingConvention = CallingConvention.Cdecl)]
-        public static extern void cipher_set_operation_ex(IntPtr ctx, int operation);
-
         [DllImport(DLLNAME, CallingConvention = CallingConvention.Cdecl)]
         public static extern int cipher_get_size_ex();
     }
diff --git a/shadowsocks-csharp/Encryption/MbedTLSEncryptor.cs b/shadowsocks-csharp/Encryption/MbedTLSEncryptor.cs
index 969b9dd2..0d657f34 100644
--- a/shadowsocks-csharp/Encryption/MbedTLSEncryptor.cs
+++ b/shadowsocks-csharp/Encryption/MbedTLSEncryptor.cs
@@ -76,8 +76,17 @@ namespace Shadowsocks.Encryption
             MbedTLS.cipher_init(ctx);
             if (MbedTLS.cipher_setup( ctx, MbedTLS.cipher_info_from_string( _cipherMbedName ) ) != 0 )
                 throw new Exception();
-            // MbedTLS takes key length by bit
-            // cipher_setkey() will set the correct key schedule
+            /*
+             * MbedTLS takes key length by bit
+             * cipher_setkey() will set the correct key schedule
+             * and operation
+             *
+             *  MBEDTLS_AES_{EN,DE}CRYPT
+             *  == MBEDTLS_BLOWFISH_{EN,DE}CRYPT
+             *  == MBEDTLS_CAMELLIA_{EN,DE}CRYPT
+             *  == MBEDTLS_{EN,DE}CRYPT
+             *  
+             */
             if (MbedTLS.cipher_setkey(ctx, realkey, keyLen * 8, isCipher ? MbedTLS.MBEDTLS_ENCRYPT : MbedTLS.MBEDTLS_DECRYPT) != 0 )
                 throw new Exception();
             if (MbedTLS.cipher_set_iv(ctx, iv, ivLen) != 0)
@@ -102,23 +111,6 @@ namespace Shadowsocks.Encryption
             {
                 ctx = _decryptCtx;
             }
-
-            if (_cipher == CIPHER_AES
-                 || _cipher == CIPHER_BLOWFISH
-                 || _cipher == CIPHER_CAMELLIA)
-            {
-                /*
-                 * operation workaround
-                 *
-                 *  MBEDTLS_AES_{EN,DE}CRYPT
-                 *  == MBEDTLS_BLOWFISH_{EN,DE}CRYPT
-                 *  == MBEDTLS_CAMELLIA_{EN,DE}CRYPT
-                 *  == MBEDTLS_{EN,DE}CRYPT
-                 *  setter code in C:
-                 *      ctx->operation = operation;
-                 */
-                MbedTLS.cipher_set_operation_ex(ctx, isCipher ? MbedTLS.MBEDTLS_ENCRYPT : MbedTLS.MBEDTLS_DECRYPT);
-            }
             if (MbedTLS.cipher_update(ctx, buf, length, outbuf, ref length) != 0 )
                 throw new Exception();
         }
diff --git a/shadowsocks-csharp/Encryption/Sodium.cs b/shadowsocks-csharp/Encryption/Sodium.cs
index 3d20bdea..22a7b7a7 100755
--- a/shadowsocks-csharp/Encryption/Sodium.cs
+++ b/shadowsocks-csharp/Encryption/Sodium.cs
@@ -33,16 +33,16 @@ namespace Shadowsocks.Encryption
         private static extern IntPtr LoadLibrary(string path);
 
         [DllImport(DLLNAME, CallingConvention = CallingConvention.Cdecl)]
-        public extern static int crypto_stream_salsa20_xor_ic(byte[] c, byte[] m, ulong mlen, byte[] n, ulong ic, byte[] k);
+        public static extern int crypto_stream_salsa20_xor_ic(byte[] c, byte[] m, ulong mlen, byte[] n, ulong ic, byte[] k);
 
         [DllImport(DLLNAME, CallingConvention = CallingConvention.Cdecl)]
-        public extern static int crypto_stream_chacha20_xor_ic(byte[] c, byte[] m, ulong mlen, byte[] n, ulong ic, byte[] k);
+        public static extern int crypto_stream_chacha20_xor_ic(byte[] c, byte[] m, ulong mlen, byte[] n, ulong ic, byte[] k);
 
         [DllImport(DLLNAME, CallingConvention = CallingConvention.Cdecl)]
-        public extern static int crypto_stream_chacha20_ietf_xor_ic(byte[] c, byte[] m, ulong mlen, byte[] n, uint ic, byte[] k);
+        public static extern int crypto_stream_chacha20_ietf_xor_ic(byte[] c, byte[] m, ulong mlen, byte[] n, uint ic, byte[] k);
 
         [DllImport(DLLNAME, CallingConvention = CallingConvention.Cdecl)]
-        public extern static void ss_sha1_hmac_ex(byte[] key, uint keylen,
+        public static extern void ss_sha1_hmac_ex(byte[] key, uint keylen,
             byte[] input, int ioff, uint ilen,
             byte[] output);
     }
diff --git a/shadowsocks-csharp/View/ConfigForm.Designer.cs b/shadowsocks-csharp/View/ConfigForm.Designer.cs
index 50207095..e6a15915 100755
--- a/shadowsocks-csharp/View/ConfigForm.Designer.cs
+++ b/shadowsocks-csharp/View/ConfigForm.Designer.cs
@@ -211,7 +211,7 @@
             "bf-cfb",
             "camellia-128-cfb",
             "camellia-192-cfb",
-            "camellia-256-cfb",});
+            "camellia-256-cfb"});
             this.EncryptionSelect.Location = new System.Drawing.Point(83, 87);
             this.EncryptionSelect.Name = "EncryptionSelect";
             this.EncryptionSelect.Size = new System.Drawing.Size(160, 20);