IF EXISTS(SELECT 1 FROM SYSOBJECTS WHERE TYPE='P' AND NAME='P_TEST')
DROP PROCEDURE P_TEST
GO
CREATE PROCEDURE P_TEST(@USERNAME VARCHAR(20),@MSG VARCHAR(20) OUTPUT)
WITH ENCRYPTION
AS
BEGIN
  IF(SELECT COUNT(1) FROM Custs WHERE NAME=@USERNAME)>0
    SET @MSG='此用户名存在'
  ELSE
    SET @MSG='此用户名不存在'
END

Create PROCEDURE Decryption(@procedure sysname = NULL)
AS
SET NOCOUNT ON
DECLARE @intProcSpace bigint, @t bigint, @maxColID smallint,@procNameLength int
select @maxColID = max(subobjid) FROM
sys.sysobjvalues WHERE objid = object_id(@procedure)
--select @maxColID as 'Rows in sys.sysobjvalues'
select @procNameLength = datalength(@procedure) + 29
DECLARE @real_01 nvarchar(max)
DECLARE @fake_01 nvarchar(max)
DECLARE @fake_encrypt_01 nvarchar(max)
DECLARE @real_decrypt_01 nvarchar(max),@real_decrypt_01a nvarchar(max)
declare @objtype varchar(2),@ParentName nvarchar(max)
select @real_decrypt_01a = ''
--提取对象的类型如是存储过程还是函数，如果是触发器，还要得到其父对象的名称
select @objtype=type,@parentname=object_name(parent_object_id)
from sys.objects where [object_id]=object_id(@procedure)
-- 从sys.sysobjvalues里提出加密的imageval记录
SET @real_01=(SELECT top 1 imageval FROM sys.sysobjvalues WHERE objid =
object_id(@procedure) and valclass = 1 order by subobjid)
 
--创建一个临时表
create table #output ( [ident] [int] IDENTITY (1, 1) NOT NULL ,
[real_decrypt] NVARCHAR(MAX) )
--开始一个事务，稍后回滚
BEGIN TRAN
--更改原始的存储过程，用短横线替换
if @objtype='P'
 SET @fake_01='ALTER PROCEDURE '+ @procedure +' WITH ENCRYPTION AS select 1
 /**//*'+REPLICATE(cast('*'as nvarchar(max)), datalength(@real_01) /2 - @procNameLength)+'*/'
else if @objtype='FN'
 SET @fake_01='ALTER FUNCTION '+ @procedure +'() RETURNS INT WITH ENCRYPTION AS BEGIN RETURN 1
 /**//*'+REPLICATE(cast('*'as nvarchar(max)), datalength(@real_01) /2 - @procNameLength)+'*/ END'
else if @objtype='V'
 SET @fake_01='ALTER view '+ @procedure +' WITH ENCRYPTION AS select 1 as col
 /**//*'+REPLICATE(cast('*'as nvarchar(max)), datalength(@real_01) /2 - @procNameLength)+'*/'
else if @objtype='TR'
 SET @fake_01='ALTER trigger '+ @procedure +' ON '+@parentname+'WITH ENCRYPTION AFTER INSERT AS RAISERROR (''N'',16,10)
 /**//*'+REPLICATE(cast('*'as nvarchar(max)), datalength(@real_01) /2 - @procNameLength)+'*/'
EXECUTE (@fake_01)
--从sys.sysobjvalues里提出加密的假的
SET @fake_encrypt_01=(SELECT top 1 imageval FROM sys.sysobjvalues WHERE objid =
object_id(@procedure) and valclass = 1 order by subobjid )
if @objtype='P'
 SET @fake_01='Create PROCEDURE '+ @procedure +' WITH ENCRYPTION AS select 1
 /**//*'+REPLICATE(cast('*'as nvarchar(max)), datalength(@real_01) /2 - @procNameLength)+'*/'
else if @objtype='FN'
 SET @fake_01='CREATE FUNCTION '+ @procedure +'() RETURNS INT WITH ENCRYPTION AS BEGIN RETURN 1
 /**//*'+REPLICATE(cast('*'as nvarchar(max)), datalength(@real_01) /2 - @procNameLength)+'*/ END'
else if @objtype='V'
 SET @fake_01='Create view '+ @procedure +' WITH ENCRYPTION AS select 1 as col
 /**//*'+REPLICATE(cast('*'as nvarchar(max)), datalength(@real_01) /2 - @procNameLength)+'*/'
else if @objtype='TR'
 SET @fake_01='Create trigger '+ @procedure +' ON '+@parentname+'WITH ENCRYPTION AFTER INSERT AS RAISERROR (''N'',16,10)
 /**//*'+REPLICATE(cast('*'as nvarchar(max)), datalength(@real_01) /2 - @procNameLength)+'*/'
--开始计数
SET @intProcSpace=1
--使用字符填充临时变量
SET @real_decrypt_01 = replicate(cast('A'as nvarchar(max)), (datalength(@real_01) /2 ))
--循环设置每一个变量，创建真正的变量
--每次一个字节
SET @intProcSpace=1
--如有必要，遍历每个@real_xx变量并解密
WHILE @intProcSpace<=(datalength(@real_01)/2)
BEGIN
--真的和假的和加密的假的进行异或处理
SET @real_decrypt_01 = stuff(@real_decrypt_01, @intProcSpace, 1,
NCHAR(UNICODE(substring(@real_01, @intProcSpace, 1)) ^
(UNICODE(substring(@fake_01, @intProcSpace, 1)) ^
UNICODE(substring(@fake_encrypt_01, @intProcSpace, 1)))))
SET @intProcSpace=@intProcSpace+1
END
 
 
--通过sp_helptext逻辑向表#output里插入变量
insert #output (real_decrypt) select @real_decrypt_01
--select real_decrypt AS '#output chek' from #output --测试
-- -------------------------------------
--开始从sp_helptext提取
-- -------------------------------------
declare @dbname sysname
,@BlankSpaceAdded int
,@BasePos int
,@CurrentPos int
,@TextLength int
,@LineId int
,@AddOnLen int
,@LFCR int --回车换行的长度
,@DefinedLength int
,@SyscomText nvarchar(max)
,@Line nvarchar(255)
Select @DefinedLength = 255
SELECT @BlankSpaceAdded = 0 --跟踪行结束的空格。注意Len函数忽略了多余的空格
CREATE TABLE #CommentText
(LineId int
,Text nvarchar(255) collate database_default)
--使用#output代替sys.sysobjvalues
DECLARE ms_crs_syscom CURSOR LOCAL
FOR SELECT real_decrypt from #output
ORDER BY ident
FOR READ ONLY
--获取文本
SELECT @LFCR = 2
SELECT @LineId = 1
OPEN ms_crs_syscom
FETCH NEXT FROM ms_crs_syscom into @SyscomText
WHILE @@fetch_status >= 0
BEGIN
SELECT @BasePos = 1
SELECT @CurrentPos = 1
SELECT @TextLength = LEN(@SyscomText)
WHILE @CurrentPos != 0
BEGIN
--通过回车查找行的结束
SELECT @CurrentPos = CHARINDEX(char(13)+char(10), @SyscomText,
@BasePos)
--如果找到回车
IF @CurrentPos != 0
BEGIN
--如果@Lines的长度的新值比设置的大就插入@Lines目前的内容并继续
While (isnull(LEN(@Line),0) + @BlankSpaceAdded +
@CurrentPos-@BasePos + @LFCR) > @DefinedLength
BEGIN
SELECT @AddOnLen = @DefinedLength-(isnull(LEN(@Line),0) +
@BlankSpaceAdded)
INSERT #CommentText VALUES
( @LineId,
isnull(@Line, N'') + isnull(SUBSTRING(@SyscomText,
@BasePos, @AddOnLen), N''))
SELECT @Line = NULL, @LineId = @LineId + 1,
@BasePos = @BasePos + @AddOnLen, @BlankSpaceAdded = 0
END
SELECT @Line = isnull(@Line, N'') +
isnull(SUBSTRING(@SyscomText, @BasePos, @CurrentPos-@BasePos + @LFCR), N'')
SELECT @BasePos = @CurrentPos+2
INSERT #CommentText VALUES( @LineId, @Line )
SELECT @LineId = @LineId + 1
SELECT @Line = NULL
END
ELSE
--如果回车没找到
BEGIN
IF @BasePos <= @TextLength
BEGIN
--如果@Lines长度的新值大于定义的长度
While (isnull(LEN(@Line),0) + @BlankSpaceAdded +
@TextLength-@BasePos+1 ) > @DefinedLength
BEGIN
SELECT @AddOnLen = @DefinedLength -
(isnull(LEN(@Line),0) + @BlankSpaceAdded)
INSERT #CommentText VALUES
( @LineId,
isnull(@Line, N'') + isnull(SUBSTRING(@SyscomText,
@BasePos, @AddOnLen), N''))
SELECT @Line = NULL, @LineId = @LineId + 1,
@BasePos = @BasePos + @AddOnLen, @BlankSpaceAdded =
0
END
SELECT @Line = isnull(@Line, N'') +
isnull(SUBSTRING(@SyscomText, @BasePos, @TextLength-@BasePos+1 ), N'')
if LEN(@Line) < @DefinedLength and charindex(' ',
@SyscomText, @TextLength+1 ) > 0
BEGIN
SELECT @Line = @Line + ' ', @BlankSpaceAdded = 1
END
END
END
END
FETCH NEXT FROM ms_crs_syscom into @SyscomText
END
IF @Line is NOT NULL
INSERT #CommentText VALUES( @LineId, @Line )
select Text from #CommentText order by LineId
CLOSE ms_crs_syscom
DEALLOCATE ms_crs_syscom
DROP TABLE #CommentText
-- -------------------------------------
--结束从sp_helptext提取
-- -------------------------------------
--删除用短横线创建的存储过程并重建原始的存储过程
ROLLBACK TRAN
DROP TABLE #output
GO
启用DAC
SP_CONFIGURE 'remote admin connections';
GO
----0：仅允许本地连接使用 DAC，1：允许远程连接使用 DAC
SP_CONFIGURE 'remote admin connections', 0;
GO
RECONFIGURE WITH OVERRIDE;
GO 

USE TEST
EXEC Decryption P_TEST
GO