MD5的C#和Java同步

這是一個普遍的問題，本身md5在實現的時候方式就很多，結果還不一致，更別談跨語言了，今天把兩種各自試了一下，結論如下

1，32位的加密一定要選字元編碼，並且通過與java的測試，發現除了utf8,ascii和default（default對應java的gbk，但這個應該取決於當前作業系統）這幾種編碼方式，其它的編碼方式輸出的結果一個都對不上

2，16位在C#不過是32位裡面截取了一小段

3，想要C#和Java，以及其它語言各自md5後能互相識別，那還是在編碼的時候選擇utf8吧，當然你一定要用ascii和gbk也可以，但是你得知道，C#裡面找個gbk都難找，除非你知道它的code page（http://msdn.microsoft.com/en-us/library/system.text.encoding.codepage.aspx），為了避免麻煩，還是用通行的utf8吧

用C#寫了一個控制台應用，把結果輸出在後面了，各種語言可以自己去對照，英文用的是zkx，中文用的是中科信

using System;using System.Security.Cryptography;using System.Text;using System.Web.Security;namespace temp{    class Program    {        static void Main(string[] args)        {            Console.WriteLine("=======zkx==========");            Console.WriteLine("utf8:"+MD5_32("zkx"));            Console.WriteLine("default: "+MD5_32("zkx", Encoding.Default));            Console.WriteLine("ascii: "+MD5_32("zkx", Encoding.ASCII));            Console.WriteLine("unicode: "+MD5_32("zkx", Encoding.Unicode));            Console.WriteLine("utf32: "+MD5_32("zkx", Encoding.UTF32));            Console.WriteLine("utf7: " + MD5_32("zkx", Encoding.UTF7));            Console.WriteLine("========中科信=========");            Console.WriteLine("utf8:" + MD5_32("中科信"));            Console.WriteLine("default: " + MD5_32("中科信", Encoding.Default));            Console.WriteLine("ascii: " + MD5_32("中科信", Encoding.ASCII));            Console.WriteLine("unicode: " + MD5_32("中科信", Encoding.Unicode));            Console.WriteLine("utf32: " + MD5_32("中科信", Encoding.UTF32));            Console.WriteLine("utf7: " + MD5_32("中科信", Encoding.UTF7));            Console.WriteLine("=============");            Console.WriteLine("zkx@16\t" + MD5_16("zkx"));            Console.WriteLine("zkx@16\t" + MD5_16b("zkx"));            Console.WriteLine("zkx@16\t" + MD5_web("zkx"));            Console.WriteLine("中科信@16\t" + MD5_16("中科信"));            Console.WriteLine("中科信@16\t" + MD5_16b("中科信"));            Console.WriteLine("中科信@16\t" + MD5_web("中科信"));            Console.WriteLine("================");            Console.WriteLine("zkx@16\t" + Encrypt("zkx"));            Console.WriteLine("中科信@16\t" + Encrypt("中科信"));        }        static string MD5_32(string input)        {            return MD5_32(input, null);        }        /// <summary>        /// MD5 32位加密        /// </summary>        /// <param name="input">源字串</param>        /// <param name="encoding">字元編碼，預設（傳入null)為UTF8</param>        /// <returns></returns>        static string MD5_32(string input,Encoding encoding)        {            if (encoding==null)            {                encoding = Encoding.UTF8;            }            //using (MD5CryptoServiceProvider md5Hash = new MD5CryptoServiceProvider())            using (MD5 md5Hash = MD5.Create())            {                // Convert the input string to a byte array and compute the hash.                byte[] data = md5Hash.ComputeHash(encoding.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();            }        }        /// <summary>        /// MD5 16位加密 加密後密碼為大寫        /// </summary>        /// <param name="input"></param>        /// <returns></returns>        public static string MD5_16(string input)        {            using (MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider())            {                string t2 = BitConverter.ToString(md5.ComputeHash(UTF8Encoding.Default.GetBytes(input)), 4, 8);                t2 = t2.Replace("-", "");                return t2;            }        }        /// <summary>        /// MD5 16位加密 加密後密碼為大寫        /// </summary>        /// <param name="input"></param>        /// <returns></returns>        public static string MD5_16b(string input)        {            using (MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider())            {                return BitConverter.ToString(md5.ComputeHash(UTF8Encoding.Default.GetBytes(input)), 4, 8);            }        }        public static string MD5_web(string input)        {            return FormsAuthentication.HashPasswordForStoringInConfigFile(input, "MD5");        }        //等於MD5_32方法每兩位加一個虛線        public static string Encrypt(string password)        {            ///擷取Byte數組            ///顯然，此處也是根據不同的字元編碼產生不同的輸出的，MD5_32方法示範過，此處不再封裝成變數了            Byte[] clearBytes = Encoding.Unicode.GetBytes(password);            ///擷取Hash值            Byte[] hashedBytes = ((HashAlgorithm)CryptoConfig.CreateFromName("MD5")).ComputeHash(clearBytes);            ///擷取加密後的資訊            return BitConverter.ToString(hashedBytes);        }    }}

輸出：