取得 MD5 (SHA1) 的三種方法
取的字串的 MD5(SHA1) 數值的三種方法：
1. 使用 System.Web.Security 命名空間
FormsAuthentication.HashPasswordForStoringInConfigFile 方法
2. 使用 System.Security.Cryptography 命名空間
MD5CryptoServiceProvider 類別、 SHA1CryptoServiceProvider 類別
3. 使用 SQL Server 2005 的內建函數
hashbytes
取得 MD5 範例的程式碼：
1: private void button1_Click(object sender, EventArgs e)
2: {
3: string source = "Test String";
4:
5: // Method 1: FormsAuthentication.HashPasswordForStoringInConfigFile
6: string m1 = FormsAuthentication.HashPasswordForStoringInConfigFile(source, "MD5").ToLower();
7: string m2 = GetMD5(source);
8: string m3 = MD5Sql(source);
9:
10: MessageBox.Show(string.Format("source: {0}, m1:{1}, m22:{2}, m3:{3}", source, m1, m2, m3));
11: }
12:
13: // Method 2: MD5CryptoServiceProvider
14: private string GetMD5(string source)
15: {
16: MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
17: byte[] bytValue = Encoding.UTF8.GetBytes(source);
18: byte[] bytHash = md5.ComputeHash(bytValue);
19: md5.Clear();
20:
21: StringBuilder sb = new StringBuilder();
22: for (int i = 0; i < bytHash.Length; i++)
23: {
24: sb.Append(bytHash[i].ToString("X").PadLeft(2, '0'));
25: }
26:
27: return sb.ToString().ToLower();
28: }
29:
30: // Method 3: SQL Server 2005 MD5
31: public string MD5Sql(string source)
32: {
33: string strConn = @"Connectionstring";
34: SqlConnection conn = new SqlConnection(strConn);
35: SqlCommand cmd = new SqlCommand("select master.sys.fn_VarBinToHexStr(hashbytes('MD5', @sDataIn))", conn);
36: cmd.Parameters.Add("@sDataIn", SqlDbType.VarChar);
37: cmd.Parameters["@sDataIn"].Value = source;
38:
39: conn.Open();
40: string s = cmd.ExecuteScalar().ToString().Substring(2).ToLower();
41: conn.Close();
42:
43: return s;
44: }