使用 Transact-SQL开启CLR

sp_configure 'show advanced options',1
RECONFIGURE

sp_configure 'clr enabled',1
RECONFIGURE

DECLARE @hash AS BINARY(64) = (SELECT HASHBYTES('SHA2_512', (SELECT * FROM OPENROWSET (BULK 'C:\clrDES.dll', SINGLE_BLOB) AS [Data])))

EXEC sp_add_trusted_assembly @hash

编写CLR集成托管DLL

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 });
    }

    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 });
    }

    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;
    }
}

调用示例

select dbo.des_encrypt(N'hello world', N'88888888');
select dbo.des_decrypt(N'+GeLDT6kAxZlm2pnFX8X4w==',N'88888888');