How to Convert between byte and Hex string

Please see the function below:

        /// Convert a string of hex digits (ex: E4 CA B2) to a byte array. 
        /// The string containing the hex digits (with or without spaces). 
        /// Returns an array of bytes.
        private byte[] HexStringToByteArray(string s)
        {
            s = s.Replace(" ", "");
            byte[] buffer = new byte[s.Length / 2];
            for (int i = 0; i < s.Length; i += 2)
                buffer[i / 2] = (byte)Convert.ToByte(s.Substring(i, 2), 16);
            return buffer;
        }

        ///  Converts an array of bytes into a formatted string of hex digits (ex: E4 CA B2)
        ///  The array of bytes to be translated into a string of hex digits. 
        ///  Returns a well formatted string of hex digits with spacing. 
        private string ByteArrayToHexString(byte[] data)
        {
            StringBuilder sb = new StringBuilder(data.Length * 3);
            foreach (byte b in data)
                sb.Append(Convert.ToString(b, 16).PadLeft(2, '0').PadRight(3, ' '));
            return sb.ToString().ToUpper();
        }