"Xorer" executable

[OlivierS]

Hello,

Here is the source code of a program that xors a file (from which we type the location/name, xored file is copied to file "output.fle").
I guess there are many flaws in it:

-the xor process is a bit trivial, this encryption is very easy to crack.
-the file size must not exceed 2GB, the file title must not exceed 64 bytes.
-Im pretty sure there are other concerns, in matter of security as in term of efficiency.
Thanks in advance for your advices.


Olivier

PS:
(build.bat file):
ml64 madXor.asm /link /subsystem:console /entry:main

(Visual Studio 2022 Developer Command Prompt v17.6.4)

[NoCforMe]

First of all: why 64-bit? This would be so much easier in 32-bit. And 64-bit is total overkill for the trivial task you're doing here.

[Vortex]

Hi OlivierS,

You would like to use the Masm64 SDK making easier coding.

[OlivierS]

Hi and thank you for your replies.
Why 64 bits? My computer OS is a windows 64 machine and the book i have is about 64 bit masm programming. Those are the reasons why i did not choose 32 bits. As you probably noticed, im a beginner(lol). I didnot know i could compile in x32 bit on a win64 machine. I will take a look at the documentation on the forum.
@Vortex, i will take a look at the masm64 sdk for easier coding.
Thank you all

[NoCforMe]

It is really so much easier (Win32) and it still works like a charm even on fancy-schmancy 64-bit systems.

BTW, 32-bit is referred to as "X86" (after the Intel line of processors), while 64-bit is "X64".

[alCoPaUL]

Hello,

Here is the source code of a program that xors a file (from which we type the location/name, xored file is copied to file "output.fle").
I guess there are many flaws in it:

-the xor process is a bit trivial, this encryption is very easy to crack.
-the file size must not exceed 2GB, the file title must not exceed 64 bytes.
-Im pretty sure there are other concerns, in matter of security as in term of efficiency.
Thanks in advance for your advices.


Olivier

PS:
(build.bat file):
ml64 madXor.asm /link /subsystem:console /entry:main

(Visual Studio 2022 Developer Command Prompt v17.6.4)

2 byte password resets at FF+1 (range: 0, FF) if you're implementing byte per byte XORing but visualize the extra routines that you can use at full, say, rax register..

and wait, there are more registers...