Hex.cs

namespace System.Security.Util
{
    internal static class Hex
    {
        private static char HexDigit(int num)
        {
            return (char)((num < 10) ? (num + 48) : (num + 55));
        }

        public static string EncodeHexString(byte[] sArray)
        {
            string result = null;
            if (sArray != null)
            {
                char[] array = new char[sArray.Length * 2];
                int i = 0;
                int num = 0;
                for (; i < sArray.Length; i++)
                {
                    int num2 = (sArray[i] & 0xF0) >> 4;
                    array[num++] = HexDigit(num2);
                    num2 = (sArray[i] & 0xF);
                    array[num++] = HexDigit(num2);
                }
                result = new string(array);
            }
            return result;
        }

        internal static string EncodeHexStringFromInt(byte[] sArray)
        {
            string result = null;
            if (sArray != null)
            {
                char[] array = new char[sArray.Length * 2];
                int num = sArray.Length;
                int num2 = 0;
                while (num-- > 0)
                {
                    int num4 = (sArray[num] & 0xF0) >> 4;
                    array[num2++] = HexDigit(num4);
                    num4 = (sArray[num] & 0xF);
                    array[num2++] = HexDigit(num4);
                }
                result = new string(array);
            }
            return result;
        }

        public static int ConvertHexDigit(char val)
        {
            if (val <= '9' && val >= '0')
            {
                return val - 48;
            }
            if (val >= 'a' && val <= 'f')
            {
                return val - 97 + 10;
            }
            if (val >= 'A' && val <= 'F')
            {
                return val - 65 + 10;
            }
            throw new ArgumentException(Environment.GetResourceString("ArgumentOutOfRange_Index"));
        }

        public static byte[] DecodeHexString(string hexString)
        {
            if (hexString == null)
            {
                throw new ArgumentNullException("hexString");
            }
            bool flag = false;
            int num = 0;
            int num2 = hexString.Length;
            if (num2 >= 2 && hexString[0] == '0' && (hexString[1] == 'x' || hexString[1] == 'X'))
            {
                num2 = hexString.Length - 2;
                num = 2;
            }
            if (num2 % 2 != 0 && num2 % 3 != 2)
            {
                throw new ArgumentException(Environment.GetResourceString("Argument_InvalidHexFormat"));
            }
            byte[] array;
            if (num2 >= 3 && hexString[num + 2] == ' ')
            {
                flag = true;
                array = new byte[num2 / 3 + 1];
            }
            else
            {
                array = new byte[num2 / 2];
            }
            int num3 = 0;
            while (num < hexString.Length)
            {
                int num4 = ConvertHexDigit(hexString[num]);
                int num5 = ConvertHexDigit(hexString[num + 1]);
                array[num3] = (byte)(num5 | (num4 << 4));
                if (flag)
                {
                    num++;
                }
                num += 2;
                num3++;
            }
            return array;
        }
    }
}