public static string GetFileMD(string filePath)
     {
       MDCryptoServiceProvider md = new MDCryptoServiceProvider();
       FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
       byte[] result = md.ComputeHash(fs);
       md.Clear();
       StringBuilder sb = new StringBuilder();
       for (int i = ; i < result.Length; i++)
       {
         sb.Append(result[i].ToString("X"));
       }
       return sb.ToString();
     }

 public static string GetFileSHA(string filePath)
     {
       SHA sha = new SHACryptoServiceProvider();
       FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
       byte[] result = sha.ComputeHash(fs);
       sha.Clear();
       StringBuilder sb = new StringBuilder();
       for (int i = ; i < result.Length; i++)
       {
         sb.Append(result[i].ToString("X"));
       }
       return sb.ToString();
     }

public static class ValidHelper
   {
     public static string GetFileHash(string filePath, HashAlgorithm algorithm)
     {
       FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.Read);
       byte[] result = algorithm.ComputeHash(fs);
       algorithm.Clear();
       StringBuilder sb = new StringBuilder();
       for (int i = ; i < result.Length; i++)
       {
         sb.Append(result[i].ToString("X"));
       }
       return sb.ToString();
     }
 
     public static string GetFileMD(string filePath)
     {
       MDCryptoServiceProvider md = new MDCryptoServiceProvider();
       return GetFileHash(filePath, md);
     }
 
     public static string GetFileSHA(string filePath)
     {
       SHA sha = new SHACryptoServiceProvider();
       return GetFileHash(filePath, sha);
     }
 
     public static string GetFileSHA(string filePath)
     {
       SHA sha = SHA.Create();
       return GetFileHash(filePath, sha);
     }
 
     public static string GetFileSHA(string filePath)
     {
       SHA sha = SHA.Create();
       return GetFileHash(filePath, sha);
     }
 
     public static string GetFileSHA(string filePath)
     {
       SHA sha = SHA.Create();
       return GetFileHash(filePath, sha);
     }
   }