using System;
using System.Text.RegularExpressions;
 
class Program
{
  static void Main()
  {
    string input = "Random string CA761232-ED42-11CE-BACD-00AA0057B223 random string";
 
    Match match = Regex.Match(input,
      @"((?:(?:\s*\{*\s*(?:0x[\dA-F]+)\}*\,?)+)|(?<![a-f\d])[a-f\d]{32}(?![a-f\d])|" +
      @"(?:\{\(|)(?<![A-F\d])[A-F\d]{8}(?:\-[A-F\d]{4}){3}\-[A-F\d]{12}(?![A-F\d])(?:\}|\)|))");
 
    if (match.Success)
    {
      string key = match.Groups[1].Value;
      Console.WriteLine(key);
    }
    else
    {
      Console.WriteLine("NO MATCH");
    }
  }
}