GenAESCMAC.cs

using System;
using System.IO;
using System.Linq;
using System.Security.Cryptography;

namespace EdgeAuther
{
    class GenAESCMAC
    {
        //Code taken from https://stackoverflow.com/questions/29163493/aes-cmac-calculation-c-sharp
        public static byte[] AESEncrypt(byte[] key, byte[] iv, byte[] data)
        {
            using (MemoryStream ms = new MemoryStream())
            {
                AesCryptoServiceProvider aes = new AesCryptoServiceProvider
                {
                    Mode = CipherMode.CBC,
                    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();
                }
            }
        }
        public 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;
        }
        public static byte[] AESCMAC(byte[] key, byte[] data)
        {
            byte[] L = AESEncrypt(key, new byte[16], new byte[16]);

            byte[] FirstSubkey = Rol(L);
            if ((L[0] & 0x80) == 0x80)
                FirstSubkey[15] ^= 0x87;

            byte[] SecondSubkey = Rol(FirstSubkey);
            if ((FirstSubkey[0] & 0x80) == 0x80)
                SecondSubkey[15] ^= 0x87;

            if (((data.Length != 0) && (data.Length % 16 == 0)) == true)
            {
                for (int j = 0; j < FirstSubkey.Length; j++)
                    data[data.Length - 16 + j] ^= FirstSubkey[j];
            }
            else
            {
                byte[] padding = new byte[16 - data.Length % 16];
                padding[0] = 0x80;

                data = data.Concat<byte>(padding.AsEnumerable()).ToArray();

                for (int j = 0; j < SecondSubkey.Length; j++)
                    data[data.Length - 16 + j] ^= SecondSubkey[j];
            }

            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;
        }
    }
}