Generate Random Token in c#

TokenHelper.cs

public class TokenUtil
{
  private const string Alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
  private static readonly Random Random = new Random();

  /// <summary>
  ///     랜덤 토큰 생성기, 시작 시간에 의존됨
  ///     NOTE : 강력한 랜덤 스트링 생성기가 필요하다면
  ///     https://stackoverflow.com/questions/32932679/using-rngcryptoserviceprovider-to-generate-random-string 참고
  /// </summary>
  /// <param name="length"></param>
  /// <returns></returns>
  public static string GenerateToken(int length)
  {
    return GenerateToken(Alphabet, length);
  }

  public static string GenerateToken(string characters, int length)
  {
    return new string(Enumerable
      .Range(0, length)
      .Select(num => characters[Random.Next() % characters.Length])
      .ToArray());
  }

  public static string GenerateHash(string text)
  {
    using (var hash = SHA256.Create())
    {
      return Convert.ToBase64String(hash.ComputeHash(Encoding.UTF8.GetBytes(text)));
    }
  }

  /// <summary>
  ///     해시와 텍스트 비교
  /// </summary>
  /// <param name="hash"></param>
  /// <param name="text"></param>
  /// <returns>텍스트와 해시를 비교하여 같다면 true, 아니라면 false</returns>
  public static bool CompareHash(string hash, string text)
  {
    return GenerateHash(text) == hash;
  }
}