HexadecimalExtensions.cs

using System;
using System.Linq;

namespace SystemExtensions
{
    public static class HexadecimalExtensions
    {

        /// <summary>
        /// Converts a byte array to a hexadecimal string.
        /// </summary>
        /// <param name="bytes">The byte array to convert.</param>
        /// <returns>A hexadecimal string.</returns>
        public static string ToHexadecimalString(this byte[] bytes)
        {
            return new string(bytes.SelectMany(x => x.ToString("x2").ToCharArray()).ToArray());
        }

        /// <summary>
        /// Converts a hexadecimal string to a byte array.
        /// </summary>
        /// <param name="hex">The hexadecimal string to convert.</param>
        /// <returns>A byte array.</returns>
        public static byte[] ToByteArray(this string hex)
        {
            return Enumerable.Range(0, hex.Length)
                             .Where(x => x % 2 == 0)
                             .Select(x => Convert.ToByte(hex.Substring(x, 2), 16))
                             .ToArray();
        }

    }
}