public static string GetMD5HashFromFile(string fileName){try{FileStream file = new FileStream(fileName, FileMode.Open);System.Security.Cryptography.MD5 md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();byte[] retVal = md5.ComputeHash(file);file.Close();StringBuilder sb = new StringBuilder();for (int i = 0; i < retVal.Length; i++){sb.Append(retVal[i].ToString("x2"));}return sb.ToString();}catch (Exception ex){throw new Exception("GetMD5HashFromFile() fail,error:" + ex.Message);}}

public static string GetMd5Hash(Stream input){MD5CryptoServiceProvider md5Hasher = new MD5CryptoServiceProvider();byte[] data = md5Hasher.ComputeHash(input);input.Seek(0, SeekOrigin.Begin);StringBuilder sBuilder = new StringBuilder();for (int i = 0; i < data.Length; i++){sBuilder.Append(data[i].ToString("x2"));}return sBuilder.ToString();}

public static string GetMd5Hash(string input){// Create a new instance of the MD5CryptoServiceProvider object.MD5CryptoServiceProvider md5Hasher = new MD5CryptoServiceProvider();// Convert the input string to a byte array and compute the hash.byte[] data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(input));// Create a new Stringbuilder to collect the bytes// and create a string.StringBuilder sBuilder = new StringBuilder();// Loop through each byte of the hashed data // and format each one as a hexadecimal string.for (int i = 0; i < data.Length; i++){sBuilder.Append(data[i].ToString("x2"));}// Return the hexadecimal string.return sBuilder.ToString();}

       // Verify a hash against a string. md5值不区分大小写public static bool VerifyMd5Hash(string input, string hash){// Hash the input.string hashOfInput = getMd5Hash(input);// Create a StringComparer an compare the hashes.StringComparer comparer = StringComparer.OrdinalIgnoreCase;if (0 == comparer.Compare(hashOfInput, hash)){return true;}else{return false;}}