CLR函数 SQL直接调用 C# DLL MSSQL DES 加解密

（原 ：http://topic.csdn.net/u/20100929/17/21bfc421-4ace-435f-baea-4d352d1015e3.html）

因业务升级，将原用户DES密文转换为MD5，需要在SQL中进行DES解密操作，故使用CLR函数实现，特此记录，以备后用。--by RYHAN

 C#程序集 dll 文件

using System;
using System.IO;
using System.Text;
using System.Data;
using System.Data.SqlTypes;
using System.Security.Cryptography;
using Microsoft.SqlServer.Server;

public class DES
{
    [SqlFunction(IsDeterministic=true, IsPrecise=true)]
    public static SqlString DESEncrypt(SqlString text, SqlString key)
    {
        if (text.IsNull || key.IsNull || key.Value.Length < 8)
            return null;

        return (SqlString)_DESEncrypt(Encoding.Default.GetBytes((string)text),
            Encoding.Default.GetBytes((string)key), 
            new byte[] { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF });
    }
    // Encrypt with DES
    private static string _DESEncrypt(byte[] text, byte[] key, byte[] iv)
    {
        string entext;

        using (MemoryStream mstream = new MemoryStream())
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            CryptoStream estream = new CryptoStream(mstream, des.CreateEncryptor(key, iv), CryptoStreamMode.Write);
            try
            {
                estream.Write(text, 0, text.Length);
                estream.FlushFinalBlock();
                entext = Convert.ToBase64String(mstream.ToArray());
            }
            finally
            {
                estream.Close();
                des.Clear();
            }
        }

        return entext;
    }

    [SqlFunction(IsDeterministic=true, IsPrecise=true)]
    public static SqlString DESDecrypt(SqlString text, SqlString key)
    {
        if (text.IsNull || key.IsNull || key.Value.Length < 8)
            return null;

        return (SqlString)_DESDecrypt(Convert.FromBase64String((string)text),
            Encoding.Default.GetBytes((string)key),
            new byte[] { 0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF });
    }
    // Decrypt with DES
    private static string _DESDecrypt(byte[] text, byte[] key, byte[] iv)
    {
        string detext;

        using (MemoryStream mstream = new MemoryStream())
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            CryptoStream estream = new CryptoStream(mstream, des.CreateDecryptor(key, iv), CryptoStreamMode.Write);
            try
            {
                estream.Write(text, 0, text.Length);
                estream.FlushFinalBlock();
                detext = Encoding.Default.GetString(mstream.ToArray());
            }
            finally
            {
                estream.Close();
                des.Clear();
            }
        }

        return detext;
    }
}

SQL CLR 函数

 use master 
 go 
 -- 启用 SQL Server 的 CLR 功能 
 exec sp_configure 'show advanced options',1; 
 go 
 reconfigure 
 go 
 exec sp_configure 'clr enabled',1; 
 go 
 reconfigure 
 go 
  
 if object_id('dbo.des_encrypt','FS') is not null 
  drop function dbo.des_encrypt; 
 go 
  
 if object_id('dbo.des_decrypt','FS') is not null 
  drop function dbo.des_decrypt; 
 go 
  
 -- 创建程序集 
 if exists (select * from sys.assemblies where name='DES') 
  drop assembly DES; 
 go 
 create assembly DES authorization dbo 
 from 'C:\clrDES.dll' -- dll 文件路径 
 with permission_set=safe; 
 go 
  
 create function dbo.des_encrypt (@text nvarchar(max), @key nvarchar(128)) 
 returns nvarchar(max) 
 as external name DES.DES.DESEncrypt; 
 go 
  
 -- select dbo.des_encrypt(N'hello world', N'88888888'); 
  
 create function dbo.des_decrypt (@text nvarchar(max), @key nvarchar(128)) 
 returns nvarchar(max) 
 as external name DES.DES.DESDecrypt; 
 go 
  
 -- select dbo.des_decrypt(N'+GeLDT6kAxZlm2pnFX8X4w==',N'88888888'); 

因业务升级，将原用户DES密文转换为MD5，需要在SQL中进行DES解密操作，故使用CLR函数实现，特此记录，以备后用。--by RYHAN