個人程式碼程式庫のC#計算MD5和SHA1

using System;namespace myMethod{    class computeMD5andSHA1    {        /// <summary>        /// 計算檔案的 MD5 值        /// </summary>        /// <param name="fileName">要計算 MD5 值的檔案名稱和路徑</param>        /// <returns>MD5 值16進位字串</returns>        public string MD5File(string fileName)        {            return HashFile(fileName , "md5");        }        /// <summary>        /// 計算檔案的 sha1 值        /// </summary>        /// <param name="fileName">要計算 sha1 值的檔案名稱和路徑</param>        /// <returns>sha1 值16進位字串</returns>        public string SHA1File(string fileName)        {            return HashFile(fileName , "sha1");        }        /// <summary>        /// 計算檔案的雜湊值        /// </summary>        /// <param name="fileName">要計算雜湊值的檔案名稱和路徑</param>        /// <param name="algName">演算法:sha1,md5</param>        /// <returns>雜湊值16進位字串</returns>        private string HashFile(string fileName , string algName)        {            if ( !System.IO.File.Exists(fileName) )                return string.Empty;            System.IO.FileStream fs = new System.IO.FileStream(fileName , System.IO.FileMode.Open , System.IO.FileAccess.Read);            byte[] hashBytes = HashData(fs , algName);            fs.Close();            return ByteArrayToHexString(hashBytes);        }        /// <summary>        /// 計算雜湊值        /// </summary>        /// <param name="stream">要計算雜湊值的 Stream</param>        /// <param name="algName">演算法:sha1,md5</param>        /// <returns>雜湊值位元組數組</returns>        private byte[] HashData(System.IO.Stream stream , string algName)        {            System.Security.Cryptography.HashAlgorithm algorithm;            if ( algName == null )            {                throw new ArgumentNullException("algName 不能為 null");            }            if ( string.Compare(algName , "sha1" , true) == 0 )            {                algorithm = System.Security.Cryptography.SHA1.Create();            }            else            {                if ( string.Compare(algName , "md5" , true) != 0 )                {                    throw new Exception("algName 只能使用 sha1 或 md5");                }                algorithm = System.Security.Cryptography.MD5.Create();            }            return algorithm.ComputeHash(stream);        }        /// <summary>        /// 位元組數群組轉換為16進位表示的字串        /// </summary>        private string ByteArrayToHexString(byte[] buf)        {            return BitConverter.ToString(buf).Replace("-" , "");        }    }}