difficult to understand algorithm
ZXNet echo conference «code.zx»
Hello, All
there is a task: to write a simple program so that when you poke around in it there will be
It's sooo hard to understand what she's doing.
for example, xorka. if we write it down in its usual form, then we can easily see
what she does and how she does it (it’s just a cycle!). if you play tricks with the code,
like, say, jumping from address to address (using the stack), then this is also not
effective: just sit and you can understand what is being done.
it doesn’t have to be Xorka, it can be any algorithm... the main thing is that it is
It's very difficult to understand how it works. the only thing that comes to my mind is creation
virtual processor, with its own instruction system and its emulation. but even
then, having disassembled the kernel, it will be possible to compile a list of commands and it will be easy to understand
algorithms (example - Speck's calculator in ROM.. you won't see anything disasm, but
knowing the commands you can figure it out (albeit a relatively long time)).
Maybe someone knows how to make the algorithm even more difficult to read? maybe 2
virtual processors?;)
Hello Titus
quite simple:
you write your own assembler, which can assemble each command in different
variations.
let's say: LD HL,100
┌─- code ───
PUSH DE
PUSH BC
EX AF,AF'
PUSH AF
LD B,15
LD HL,85
L0 ADD A,(HL)
SUB B
INC HL
DJNZ L0
POP AF
EX AF,AF'
POP B.C.
POP DE
└── code ───
and so on 4-8 options for each team.
It will slow down and the amount of code will increase, but you will have to really understand it
long time ;)
Hello Titus
Don't waste time on nonsense. The time when it was possible to protect on the Spectrum
the program came and went. A more or less reliable option for protecting program code is
using a hardware key of the type that is inserted into LPT on IBMs. But also
there will be craftsmen here, albeit in smaller numbers, who will hack it.
By the way, what are you planning to defend? Is the object even worthwhile?
Hello Titus
I remember back in school I wrote a program like a tricky scroller, the trick was
memory optimization, i.e. required to be crammed into a minimum volume, in
As an optimizer, a bunch of conditional and unconditional transitions were used.
When a friend sat down to disassemble it “for parts” to see how it works,
the next day he came up with the phrase: “It shouldn’t work, because it’s nonsense, but it WORKS”... ;)
I didn’t even think about any kind of protection then...
Hello, psb
Why such perversions?
They will still crack :v2_wink2: (if necessary)
Hello, psb
psb> no, of course they will crack if they really NEED IT :) but you need to have the desire to CRACK
psb> missing;)
It’s unlikely to disappear, they’ll quit on principle :)
Although why crack if now in any emulator you can stop the program and that’s it
ready.
Hello Titus
Tit> Why such perversions?
Tit> They will still crack (if necessary)
no, of course they will crack if it is absolutely NECESSARY :) but it is necessary that the desire to CRACK disappears;)
Hello Sinus
Sin> write your own assembler...
wow, this is even interesting! :))) damn, it’s a cool idea :)) that’s practically what
necessary :)
Hello new art
You write your own assembler... For such perversions there are MACROES and DEFINE's. B
normal assemblers, at least.
Hello, Jukov
Juk> Don't waste time on nonsense. The time when it was possible on the Spectrum
Juk> protect the program was and gone. A less reliable protection option
Juk> program code, this is the use of a hardware key like those
Juk> is inserted into LPT on IBMs. But there are craftsmen here too, though already in
Juk> in smaller numbers that will hack it.
Juk> By the way, what are you going to defend? Is the object even worthwhile?
Nobody seemed to be talking about Spectrum...
Hello, psb
psb> but it is necessary that the desire to CRACK disappear
it's indestructible!
Hello, Vladimir Kladov
Vla> You write your own assembler... For such perversions there are MACROS and
Vla> DEFINE's. In normal assemblers, at least.
won't help. how will he choose different versions of the same macro.. and the hacker
quickly compile a table of correspondence between pieces of code and initial macros, i.e.
will spend less time than the creator of the protection. actually, in the virmaker's
logs of all kinds of code mutation engines - tons
Hello, psb
Chernov - About one method of masking programs
http:/www.citforum.ru/security/articles/mask/
Hello Orionsoft
On the PC there is quite popular software for which there are no cracks. Nobody argues that
In principle, you can hack anything, but you can cause such hemorrhoids that
the one who breaks it will suffer and decide “well, screw it.”
Hello Orionsoft
On the PC there is quite popular software for which there are no cracks. Nobody argues that
In principle, you can hack anything, but you can cause such hemorrhoids that
the one who breaks it will suffer and decide “well, screw it.”
Hello Sinus
Well.. generally speaking, I don’t need this in relation to the Spectrum.. and not for PROTECTION
programs.. this is of course, those days are already gone.. and I take into account emulators. yes
That’s the crap, that even with an emulator, stupid debugging capabilities,
quacking, etc., it was difficult to understand what was there and how it was calculated..
so that it would be easier to _guess_ the essence of what is happening than to get into the code and understand.
I won’t tell you why exactly yet, but maybe I will when I do;)
Hello, Electrician
you won't be tormented.
It’s just that no one needs such software (reading is not needed for those who can break it)
Hello, psb
Well, here’s a normal option for you: by riveting a ton of macros or ASM, write which
will do the same, only he will also choose at random.
and if there are also left-handed pieces of code (that don’t really do anything), insert such an asm
would be, then he wouldn’t have had a price.
True, then you yourself will hesitate to debug your own code ;)
Hello, Jukov
It won't work in this version, it will work in the next one.
I also know one funny little thing that 90% of emuls will not swallow, well
so what?
Hello Sinus
in general, I roughly figured out what could be done :)
thanks everyone :)
Hello, psb
For any emulator there is a hole. They are not so ideal, I know one Fenka,
which will work on any real world, but will not work on UNREALE.
Hello, psb
psb> there is a task: write a simple program so that when poking around in it
psb> it was sooo hard to understand what she was doing.
psb>
psb> for example, xorka. if we write it down in its usual form, then we
psb> we can easily see what it does and how it does it (it's just a cycle!). if
psb> do tricks with the code, like, say, jump from address to
psb> address (using the stack), then this is also not effective: enough
psb> sit and you can understand what is being done.
psb>
psb> this is not necessarily Xorka, it can be any algorithm... the main thing is
psb> so that it is very difficult to understand how it works. comes to mind
psb> only creating a virtual processor, with its own command system and
psb> its emulation. but even then, having disassembled the kernel, it will be possible to compose
psb> list of commands and it is already easy to understand the algorithms (example - Spekov
psb> calculator in ROM.. you won’t see anything with dissam, but knowing the commands you can
psb> figure it out (even if it takes a relatively long time)).
psb> psb> Maybe someone knows how to make the algorithm even more difficult to read?
psb> maybe 2 virtual processors?;)
I once loved this very much... And I made two of my defenses... the first was in
program http://zxaaa.narod.ru/DEMO/ZXCLUB.ZIP it is simple, but the second one was
based on insanely confusing code
http://www.entire.nm.ru/speccy/PITON.SCL ... As a result, the game takes up 9 kilobytes
the game itself, and 10 kilobytes are occupied by protection. This game was a bet with my friend
Fine Soft, I wrote a “fak” on it and he had to remove it... So this is
didn't happen...
Hello SMT
SMT> will not help. how it will select different variants of one macro.. and
SMT> a hacker will quickly create a table of correspondence between pieces of code and the original ones
SMT> macros, i.e. will spend less time than the creator of the protection.
SMT> actually, in the virusmaker logs of all kinds of code mutation engines -
SMT> tons
I didn't understand something. Among other things, the macro can include the generation of the following
random number (call nested macro), and based on this number select
any branch from those implemented. All that remains is to set the starting number for the build
in a pseudo-random sequence.
Hello Titus
Titus
wow ;)
instructions: after launching, randomly and quickly press the mouse buttons.
if the lower part of the curb is repainted from black to some other color, then
you are real or a good emulsion.
unreal doesn't work.
I haven’t tested zemu yet (although in theory it should work)
PS Perhaps old DOS emuls will work.
Zyy. Glitches are possible in real life if the mouse is with a controller.
┌─- code ───
ORG #8000
LD BC,#FADF
LD H,0
LOOP HALT
LD DE,1000
IN A,(C)
AND 7
OUT(#FE),A
LD L,A
LOOP0 IN A,(C)
AND 7
OUT(#FE),A
DEC DE
LD A,D
OR E
JP NZ,LOOP0
IN A,(C)
AND 7
SUB L
ORH
LD H,A
OUT(#FE),A
XOR A
IN A,(#FE)
OR#E0
INC A
JP Z,LOOP
RET
└── code ───
Zyyy. It's not all funny stuff
Hello, Vladimir Kladov
Vla> An elementary trick (I didn’t watch this one, maybe this is it): in
Vla> in real life, pressing the keyboard occurs at any time, not just
Vla> at the frame boundary, and there is also contact bounce. Is it necessary?
Vla> In my opinion, this is completely useless.
Why look, it’s clear that this is it: v2_smile:
Hello Titus
Of course, no one needs this.
I just answered Comrade Zhukov that there are chips that emulators do not emulate
tons, and the most basic ones at that.
you can emulate everything with 100% accuracy for software that will work on
emulated machine (not a fact that it will be 100% for the viewer ;)).
But really, is it necessary?
PS if anyone really wants to run emuls for airborne surveys, then here
more correct option
┌─- code ───
ORG #8000
LD BC,#FADF
LD H,0
LOOP HALT
LD DE,800
IN A,(C)
AND 7
OUT(#FE),A
LD L,A
LOOP0 IN A,(C)
AND 7
OUT(#FE),A
SUB L
ORH
LD H,A
DEC DE
LD A,D
OR E
JP NZ,LOOP0
LD A,H
OUT(#FE),A
XOR A
IN A,(#FE)
OR#E0
INC A
JP Z,LOOP
RET
└── code ───
Hello Sinus
Sin> of course no one needs this.
Sin> I just answered Comrade Zhukov that chips that do not emulate
Sin> there are tons of emulators, and the most basic ones.
So share tons. Everything is clear about frame polling of the periphery, but besides that
Is there anything worthwhile? :v2_wink2:
Hello Titus
I have a question, and if I post my emulator, will you agree with it?
test? I have a glitch somewhere, but I can’t identify it... I’ll attach it
games that don't work on it. Or you yourself add your works to TRD,
which will not work and you will be able to identify the mess. Since I've already a hundred times
I went through command after command, but never found a flaw. It works under XP, but
video mode selects 51 hertz, I did not make other options, since this is not
corresponds to the present Speccy. Well, agree to spend your time on
identifying errors?
Hello Robus
Rob> Well, would you like to spend your time identifying errors?
Isn’t it destiny to try zxall? :v2_blush:
Hello Titus
Tit> Isn’t it fate to try zxall?
I don’t understand... What did you mean??? zxall is some kind of emulsion? program?
Hello Robus
Rob> I don’t understand... What did you mean??? zxall is some kind of emulsion?
Rob> program ?
zexall [http://www.mdfsnet.f9.co.uk/Software/Z80/Exerciser/Spectrum/]
And also read the document emuls-z80test.zip in the topic 'command bit n,(hl)',','... Titus aka Andrey Aleksandrovich Titov
Hello Robus
Rob> This game was a dispute with my friend Fine Soft, I wrote to him
Rob> "fak"
familiar story...they planted a protected file on me that needed to be broken
without Shadow RAM, as far as I remember there were two nested Xorka cycles (in total
about 56000 passes) with the R register... but there was also IM2, the handler of which
considered the checksum of the main program... and seems to have used it as
xorka parameter. I puffed for five hours, but in the end I honestly hacked it, selling it
some semblance of a Trojan. I haven’t seen better protection, more boring - yes, old
Alcatraz...
Hello Dimasty
it's different... it's not difficult to understand - it's crap... Robus is cooler