Added SMB 3.0 message signing logic

Utilities/Cryptography/AesCmac.cs

@@ -0,0 +1,96 @@
+/* Based on https://stackoverflow.com/a/30123190/3419770
+ */
+using System;
+using System.IO;
+using System.Security.Cryptography;
+
+namespace Utilities
+{
+    public static class AesCmac
+    {
+        public static byte[] CalculateAesCmac(byte[] key, byte[] buffer, int offset, int length)
+        {
+            byte[] data = ByteReader.ReadBytes(buffer, offset, length);
+            return CalculateAesCmac(key, data);
+        }
+
+        public static byte[] CalculateAesCmac(byte[] key, byte[] data)
+        {
+            // SubKey generation
+            // step 1, AES-128 with key K is applied to an all-zero input block.
+            byte[] L = AESEncrypt(key, new byte[16], new byte[16]);
+
+            // step 2, K1 is derived through the following operation:
+            byte[] FirstSubkey = Rol(L); //If the most significant bit of L is equal to 0, K1 is the left-shift of L by 1 bit.
+            if ((L[0] & 0x80) == 0x80)
+                FirstSubkey[15] ^= 0x87; // Otherwise, K1 is the exclusive-OR of const_Rb and the left-shift of L by 1 bit.
+
+            // step 3, K2 is derived through the following operation:
+            byte[] SecondSubkey = Rol(FirstSubkey); // If the most significant bit of K1 is equal to 0, K2 is the left-shift of K1 by 1 bit.
+            if ((FirstSubkey[0] & 0x80) == 0x80)
+                SecondSubkey[15] ^= 0x87; // Otherwise, K2 is the exclusive-OR of const_Rb and the left-shift of K1 by 1 bit.
+
+            // MAC computing
+            if (((data.Length != 0) && (data.Length % 16 == 0)) == true)
+            {
+                // If the size of the input message block is equal to a positive multiple of the block size (namely, 128 bits),
+                // the last block shall be exclusive-OR'ed with K1 before processing
+                for (int j = 0; j < FirstSubkey.Length; j++)
+                    data[data.Length - 16 + j] ^= FirstSubkey[j];
+            }
+            else
+            {
+                // Otherwise, the last block shall be padded with 10^i
+                byte[] padding = new byte[16 - data.Length % 16];
+                padding[0] = 0x80;
+
+                data = ByteUtils.Concatenate(data, padding);
+
+                // and exclusive-OR'ed with K2
+                for (int j = 0; j < SecondSubkey.Length; j++)
+                    data[data.Length - 16 + j] ^= SecondSubkey[j];
+            }
+
+            // The result of the previous process will be the input of the last encryption.
+            byte[] encResult = AESEncrypt(key, new byte[16], data);
+
+            byte[] HashValue = new byte[16];
+            Array.Copy(encResult, encResult.Length - HashValue.Length, HashValue, 0, HashValue.Length);
+
+            return HashValue;
+        }
+
+        private static byte[] AESEncrypt(byte[] key, byte[] iv, byte[] data)
+        {
+            using (MemoryStream ms = new MemoryStream())
+            {
+                RijndaelManaged aes = new RijndaelManaged();
+                aes.Mode = CipherMode.CBC;
+                aes.Padding = PaddingMode.None;
+
+                using (CryptoStream cs = new CryptoStream(ms, aes.CreateEncryptor(key, iv), CryptoStreamMode.Write))
+                {
+                    cs.Write(data, 0, data.Length);
+                    cs.FlushFinalBlock();
+
+                    return ms.ToArray();
+                }
+            }
+        }
+
+        private static byte[] Rol(byte[] b)
+        {
+            byte[] r = new byte[b.Length];
+            byte carry = 0;
+
+            for (int i = b.Length - 1; i >= 0; i--)
+            {
+                ushort u = (ushort)(b[i] << 1);
+                r[i] = (byte)((u & 0xff) + carry);
+                carry = (byte)((u & 0xff00) >> 8);
+            }
+
+            return r;
+        }
+    }
+}