SQL 2005 still obfuscates object encryption in a similar manner to SQL 2000.
It is simply an XOR of the encrypted bytes against a known sample to dump
out the real unencrypted bytes. The trick is getting to the the encrypted
bytes. In SQL 2005, instead of querying the SYSCOMMENTS view to get the
binary bytes to decrypt, you need to run the following query from the
dedicated admin connection (DAC) to get the bytes to decrypt:

SELECT imageval FROM sys.sysobjvalues WHERE id = object_id(@procedure) AND
valclass = 1 AND subobjid = 1

alter PROCEDURE dbo.sp_procedure$decrypt
(@procedure sysname = NULL, @revfl int = 1)
AS
SET NOCOUNT ON

IF @revfl = 1
BEGIN
PRINT 'CAUTION: THIS PROCEDURE DELETES AND REBUILDS THE ORIGINAL STORED
PROCEDURE.'
PRINT ' MAKE A BACKUP OF YOUR DATABASE BEFORE RUNNING THIS
PROCEDURE.'
PRINT ' IDEALLY, THIS PROCEDURE SHOULD BE RUN ON A NON-PRODUCTION
COPY OF THE PROCEDURE.'
PRINT ' To run the procedure, change the @revfl parameter to 0'
RETURN 0
END

DECLARE @intProcSpace bigint, @t bigint, @maxColID smallint,@intEncrypted
tinyint,@procNameLength int
--select @maxColID = max(colid),@intEncrypted = encrypted FROM
--sys.sysobjvalues WHERE id = object_id(@procedure)
--GROUP BY encrypted

--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)

select @real_decrypt_01a = ''

-- extract the encrypted imageval rows select* from sys.sysobjvalues
SET @real_01=(SELECT imageval FROM sys.sysobjvalues WHERE objid =
object_id(@procedure) and valclass = 1 and subobjid = 1 )

-- create this table for later use
create table #output ( [ident] [int] IDENTITY (1, 1) NOT NULL ,
[real_decrypt] NVARCHAR(MAX) )

-- We'll begin the transaction and roll it back later
BEGIN TRAN
-- alter the original procedure, replacing with dashes
SET @fake_01='ALTER PROCEDURE '+ @procedure +' WITH ENCRYPTION AS
'+REPLICATE('-', 40003 - @procNameLength)

EXECUTE (@fake_01)

-- extract the encrypted fake imageval rows from sys.sysobjvalues
SET @fake_encrypt_01=(SELECT imageval FROM sys.sysobjvalues WHERE objid =
object_id(@procedure) and valclass = 1 and subobjid = 1)


SET @fake_01='CREATE PROCEDURE '+ @procedure +' WITH ENCRYPTION AS
'+REPLICATE('-', 40003 - @procNameLength)
--start counter
SET @intProcSpace=1
--fill temporary variable with with a filler character
SET @real_decrypt_01 = replicate(N'A', (datalength(@real_01) /2 ))

--loop through each of the variables sets of variables, building the real
--variable
--one byte at a time.
SET @intProcSpace=1

-- Go through each @real_xx variable and decrypt it, as necessary
WHILE @intProcSpace<=(datalength(@real_01)/2)
BEGIN
--xor real & fake & fake encrypted
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


-- Load the variables into #output for handling by sp_helptext logic

insert #output (real_decrypt) select @real_decrypt_01
-- select real_decrypt AS '#output chek' from #output -- Testing

-- -------------------------------------
-- Beginning of extract from sp_helptext
-- -------------------------------------
declare @dbname sysname
,@BlankSpaceAdded int
,@BasePos int
,@CurrentPos int
,@TextLength int
,@LineId int
,@AddOnLen int
,@LFCR int --lengths of line feed carriage return
,@DefinedLength int
,@SyscomText nvarchar(4000)
,@Line nvarchar(255)


Select @DefinedLength = 255
SELECT @BlankSpaceAdded = 0 --Keeps track of blank spaces at end of
--lines. Note Len function ignores trailing blank spaces
CREATE TABLE #CommentText
(LineId int
,Text nvarchar(255) collate database_default)


-- use #output instead of sys.sysobjvalues
DECLARE ms_crs_syscom CURSOR LOCAL
FOR SELECT real_decrypt from #output
ORDER BY ident
FOR READ ONLY


-- Else get the text.

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
--Looking for end of line followed by carriage return
SELECT @CurrentPos = CHARINDEX(char(13)+char(10), @SyscomText,
@BasePos)

--If carriage return found
IF @CurrentPos != 0
BEGIN
--If new value for @Lines length will be > then the
--set length then insert current contents of @line
--and proceed.

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
--else carriage return not found
BEGIN
IF @BasePos <= @TextLength
BEGIN
--If new value for @Lines length will be > then the
--defined length
--
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

-- -------------------------------------
-- End of extract from sp_helptext
-- -------------------------------------

-- Drop the procedure that was setup with dashes and rebuild it with the
---- Version 1.1 mod; makes rebuilding hte proc unnecessary
ROLLBACK TRAN

DROP TABLE #output

GO