SQL加密函数

using System;
using System.Data;
using System.Text;
using System.IO;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using System.Security.Cryptography;
public partial class UserDefinedFunctions
{
    [Microsoft.SqlServer.Server.SqlFunction]
    public static string Encrypt_ASE(string source, string key)
    {
        string Rst;
        try
        {
            Rijndael ri = Rijndael.Create();
            ri.Key = Encoding.Default.GetBytes(key);
            ri.IV = Encoding.Default.GetBytes(key.Substring(0, 16));
            byte[] ridata = Encoding.Default.GetBytes(source);
            MemoryStream memo = new MemoryStream();
            CryptoStream Cry = new CryptoStream(memo, ri.CreateEncryptor(), CryptoStreamMode.Write);
            Cry.Write(ridata, 0, ridata.Length);
            Cry.FlushFinalBlock();
            Rst = Convert.ToBase64String(memo.ToArray());
        }
        catch
        {
            Rst = null;
        }
        return Rst;
    }
    [Microsoft.SqlServer.Server.SqlFunction]
    public static string Dencrypt_ASE(string source, string key)
    {
        string Rst;
        try
        {
            Rijndael ri = Rijndael.Create();
            ri.Key = Encoding.Default.GetBytes(key);
            ri.IV = Encoding.Default.GetBytes(key.Substring(0, 16));
            byte[] ridata = Convert.FromBase64String(source);
            MemoryStream memo = new MemoryStream();
            CryptoStream Cry = new CryptoStream(memo, ri.CreateDecryptor(), CryptoStreamMode.Write);
            Cry.Write(ridata, 0, ridata.Length);
            Cry.FlushFinalBlock();
            Rst = Encoding.Default.GetString(memo.ToArray());
        }
        catch
        {
            Rst = null;
        }
        return Rst;
    }
    [Microsoft.SqlServer.Server.SqlFunction]
    public static string Encrypt_MD5(string source)
    {
        string Rst = "";
        MD5CryptoServiceProvider MD = new MD5CryptoServiceProvider();
        byte[] mddata = Encoding.Default.GetBytes(source);
        byte[] mdbuff = MD.ComputeHash(mddata);
        foreach (byte b in mdbuff)
            Rst += b.ToString("X").PadLeft(2, '0');
        return Rst;
    }
    [Microsoft.SqlServer.Server.SqlFunction]
    public static string Encrypt_DES(string source, string key)
    {
        string Rst;
        try
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            des.Key = Encoding.Default.GetBytes(key);
            des.IV = Encoding.Default.GetBytes(key);
            byte[] desdata = Encoding.Default.GetBytes(source);
            MemoryStream memo = new MemoryStream();
            CryptoStream Cry = new CryptoStream(memo, des.CreateEncryptor(), CryptoStreamMode.Write);
            Cry.Write(desdata, 0, desdata.Length);
            Cry.FlushFinalBlock();
            Rst = Convert.ToBase64String(memo.ToArray());
        }
        catch
        {
            Rst = null;
        }
        return Rst; 
    }
    [Microsoft.SqlServer.Server.SqlFunction]
    public static string Dencrypt_DES(string source, string key)
    {
        string Rst;
        try
        {
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            des.Key = Encoding.Default.GetBytes(key);
            des.IV = Encoding.Default.GetBytes(key);
            byte[] desdata = Convert.FromBase64String(source);
            MemoryStream memo = new MemoryStream();
            CryptoStream Cry = new CryptoStream(memo, des.CreateDecryptor(), CryptoStreamMode.Write);
            Cry.Write(desdata, 0, desdata.Length);
            Cry.FlushFinalBlock();
            Rst = Encoding.Default.GetString(memo.ToArray());
        }
        catch
        {
            Rst = null;
        }
        return Rst;
    }
    [Microsoft.SqlServer.Server.SqlFunction]
    public static string Encrypt_TripleDES(string source, string key)
    {
        string Rst;
        try
        {
            TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
            tdes.Key = Encoding.Default.GetBytes(key);
            tdes.IV = Encoding.Default.GetBytes(key.Substring(0, 8));
            byte[] tdesdata = Encoding.Default.GetBytes(source);
            MemoryStream memo = new MemoryStream();
            CryptoStream Cry = new CryptoStream(memo, tdes.CreateEncryptor(), CryptoStreamMode.Write);
            Cry.Write(tdesdata, 0, tdesdata.Length);
            Cry.FlushFinalBlock();
            Rst = Convert.ToBase64String(memo.ToArray());  
        }
        catch
        {
            Rst = null;
        }
        return Rst;
    }
    [Microsoft.SqlServer.Server.SqlFunction]
    public static string Dencrypt_TripleDES(string source, string key)
    {
        string Rst;
        try
        {
            TripleDESCryptoServiceProvider tdes = new TripleDESCryptoServiceProvider();
            tdes.Key = Encoding.Default.GetBytes(key);
            tdes.IV = Encoding.Default.GetBytes(key.Substring(0, 8));
            byte[] tdesdata = Convert.FromBase64String(source);
            MemoryStream memo = new MemoryStream();
            CryptoStream Cry = new CryptoStream(memo, tdes.CreateDecryptor(), CryptoStreamMode.Write);
            Cry.Write(tdesdata, 0, tdesdata.Length);
            Cry.FlushFinalBlock();
            Rst = Encoding.Default.GetString(memo.ToArray());
        }
        catch
        {
            Rst = null;
        }
        return Rst;
    }
    [Microsoft.SqlServer.Server.SqlFunction]
    public static string Encrypt_RC2(string source, string key)
    {
        string Rst;
        try
        {
            RC2CryptoServiceProvider rc = new RC2CryptoServiceProvider();
            rc.Key = Encoding.Default.GetBytes(key);
            rc.IV = Encoding.Default.GetBytes(key);
            byte[] rcdata = Encoding.Default.GetBytes(source);
            MemoryStream memo = new MemoryStream();
            CryptoStream Cry = new CryptoStream(memo, rc.CreateEncryptor(), CryptoStreamMode.Write);
            Cry.Write(rcdata, 0, rcdata.Length);
            Cry.FlushFinalBlock();
            Rst = Convert.ToBase64String(memo.ToArray());  
        }
        catch
        {
            Rst = null;
        }
        return Rst;
    }
    [Microsoft.SqlServer.Server.SqlFunction]
    public static string dEncrypt_RC2(string source, string key)
    {
        string Rst;
        try
        {
            RC2CryptoServiceProvider rc = new RC2CryptoServiceProvider();
            rc.Key = Encoding.Default.GetBytes(key);
            rc.IV = Encoding.Default.GetBytes(key);
            byte[] rcdata = Convert.FromBase64String(source);
            MemoryStream memo = new MemoryStream();
            CryptoStream Cry = new CryptoStream(memo, rc.CreateDecryptor(), CryptoStreamMode.Write);
            Cry.Write(rcdata, 0, rcdata.Length);
            Cry.FlushFinalBlock();
            Rst = Encoding.Default.GetString(memo.ToArray());
        }
        catch
        {
            Rst = null; 
        }
        return Rst;
    }
};