String to Byte Array and Reverse

string helper.cs

public static class StringHelper
{
  public static byte[] ToByteArray(this string str)
  {
      byte[] bytes = new byte[str.Length * sizeof(char)];
      System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
      return bytes;
  }
  
  public static string GetString(this byte[] bytes)
  {
      char[] chars = new char[bytes.Length / sizeof(char)];
      System.Buffer.BlockCopy(bytes, 0, chars, 0, bytes.Length);
      return new string(chars);
  }
}