CRC checking executable's running code

[Kp]

A CRC check is also quite a bit simpler than inline function encryption/decryption, in my opinion. If you know of a rather simple (and free) method of doing such with varying start and end encrypted regions and varying degrees of encryption levels (eg, whether using different keys, different length keys, or even different algorithms  for different regions) and still maintains a decent runtime speed to the end-user on very old machines, then please be my guest and point me in the right direction. Searching google for this kind of information would take a lot of time and effort in the best case, especially since I doubt what I specifically want already exists and is free.

Skywing wrote quite a bit of code along this line several years ago.  If you can find him and get his OK for it, I can make it available to you.  He may want to keep some/all of it secret though, since at least parts of it ended up in BinaryChat's anti-leak design.

[rabbit]

If you can find him

HAHAHAHAHAHAHA!!  Yeah, right

[UserLoser.]

A CRC check is also quite a bit simpler than inline function encryption/decryption, in my opinion. If you know of a rather simple (and free) method of doing such with varying start and end encrypted regions and varying degrees of encryption levels (eg, whether using different keys, different length keys, or even different algorithms  for different regions) and still maintains a decent runtime speed to the end-user on very old machines, then please be my guest and point me in the right direction. Searching google for this kind of information would take a lot of time and effort in the best case, especially since I doubt what I specifically want already exists and is free.

Skywing wrote quite a bit of code along this line several years ago.  If you can find him and get his OK for it, I can make it available to you.  He may want to keep some/all of it secret though, since at least parts of it ended up in BinaryChat's anti-leak design.

Which BinaryChat?  Because I know some people who cracked some old binary ZeroBot and BinaryChat 2.00

[TheMinistered]

An older version of binary chat was defeated by zorm, mainly.  I helped a little but wasn't much interested-- if you want a similar version of skywing's protection then i'll post it in a couple days, I just need to find the cd.

[tA-Kane]

I'm interested ... but if it's derived from someone else's source code (even, especially, via disassembling a private executable), I don't think I should accept it without authorization from the origional author.

[Arta]

What is your goal in these endeavours?

[rabbit]

70 /\/\4|<3 1337 |-|4><, |)|_||-|!

[tA-Kane]

What is your goal in these endeavours?

1) Learn (advanced programming techniques are an interesting read for me)
2) Protect (help protect the program I'm working on against unauthorized use and/or deviations from its intended use)
3) Assist (others could benefit from the knowledge gained here)

[Arta]

Well, 1 & 3 are great, but 2 is a waste of time

Nonetheless: I don't see the value in a CRC. Once you've generated it, it'll come down to "if(CRC != what I'm expecting) quit" - which is trivially bypassed. Strong encryption of your code is the only way to go.

[tA-Kane]

Why quit? That's so obvious. I was thinking more along the lines of if (CRC != what I'm expecting), introduce specific bugs into the program.

[Arta]

Well, ok, but whatever you do won't be very hard to crack, is my point. Strong encryption, on the other hand, could be.

[Blaze]

Could you explain a method of Strong Encryption Arta?  I can't seem to think of anyway but what you just said sucked (I agree, btw).

[rabbit]

CRC code and then UPX?  Not sure if it will work, never tried it.

[Arta]

Encrypt your exe and decrypt it, or sections of it, at runtime, a la BC. Note that this isn't uncrackable either, but it's harder to break.

[UserLoser.]

CRC code and then UPX?  Not sure if it will work, never tried it.

UPX? What's the point of using public compression when you can just decompress it via "upx.exe -d yourbot.exe"

Encrypt your exe and decrypt it, or sections of it, at runtime, a la BC. Note that this isn't uncrackable either, but it's harder to break.

Yeah, but BC is also scrambled at the specific sections and must be descrambled before decrypting which makes it even more complicated.  But yeah, a method like this is really good and could take a while to crack