crypt/decrypt files

Posted on 2003-11-30
Last Modified: 2010-04-11
i need to find a tool that is able to cryipt folder and exe,dll,txt,bat files ,until they
are in execution. then it should decrypt them and run them. when execution is finished,it should restart to cryipt them. encryption/decryption mechanism should works on the computers where the crypting tool is not installed. thanks
Question by:ken_tomp
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LVL 18

Expert Comment

ID: 9847125
In order to decrypt somthing one needs the decryption key(s) and the mechanism.
While you can create a self-executing encrypted file, the decryption mechanism is built into the file and a passphrase is needed to decrypt it.
You can also encrypt a volume or create a virtual volume which is encrypted, but again you need the decryption mechanism and keys.
Perhaps if you explained more about what you're trying to accomplish...


Author Comment

ID: 9847585
dll,exe files are already crypted,shouldn't be problems here. but txt and bat files needs to be crypted to deny someone to look inside them. i need to find a way to make unreadable txt and bat files. don't forget that they should be usable,too.
LVL 18

Expert Comment

ID: 9847670
deny from whom?
You could compile the batch files to hide them from the casual observer.
The usual thing to do is hash the data files from within the application
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Author Comment

ID: 9847781
from casual observers and from peoples who works on the same pc where i work. i know how to crypt bat files,but what about txt files ? i,ve found text o' crypt 1.24 just right now,but its a very old appz,build on 1997 ! it crypts txt files,but them cannot be read by the applications,so its not useful.

Author Comment

ID: 9847829
a thing that comes in my mind is to use a not standard font,a very strange font,so no one can read text files content,but applications are able to do it ! what do u think ?

Accepted Solution

Arrummzen earned 125 total points
ID: 9848200
It is a very powerful (free) encryption program. It can do about anything you want (related to encryption). Changing the font my stop a  computer illiterate person but anyone with any training in computer security, will be able to bypass this trivially. Use true encryption and it will be almost impossible for professionals to read it (the government may be able to break it using a supercomputer, but time on those computers are expensive, and unless they have a VERY good reason of suspecting you of something they wont take the time). Strong encryption will even stop law enforcement (Unless they are VERY determined and VERY skilled). The font idea is bad, they will laugh at you (its creative, Ill give you that, but it wont work).

“ dll,exe files are already crypted,shouldn't be problems here. “ Ummm.... no they are not. Encrypted means that they are encoded by a special algorithm and can only be unlocked with a special key (unlike a password, the key cannot be bypassed). You can’t read them beacuse they are in the computers native language, not yours. Any other computer or a skilled program can read them (the programer will most likely use a disassembler which will turn it into a more human friendly format, though you will still need a skilled programer to understand it). See chicagoan’s post for a good way to encrypt object files (object files are files in the computers native language, these include .exe, .dll. .elf, and .obj).

“encryption/decryption mechanism should works on the computers where the crypting tool is not installed. thanks “

Sorry, this doesn’t exist. You have two options, have a program decrypt it or do it yourself (doing it yourself means doing a large mathematical operation on each byte, you will become board quickly). You have to install something (like gpg, which is good because it will work on any platform, from Linux, to Windows, to Mac OS-X) or have an OS that supports encryption of files like Windows 2000 or Windows XP (in Windows 2000 or Windows XP you just have to right click on a folder, and select properties, A dialog box will open, in the dialog box push the advanced button, another dialog box will come up. Check encrypt contents and then ‘Ok’ out of the dialog boxes. Windows will automatically decrypt for you when you need to edit the files in that folder using a key but no one else (no other accounts) will be able to open the file and even if someone takes your hard-drive and puts it in there computer, they wont be able to read the folder (without your account password). I think an OS tool like the Windows encryption option will best serve you. But take note that it will only work on supported operating systems like Windows 2000 and XP, and will not work if someone knows your account password (or if you leve your terminal unlocked). If you want to use your encrypted files on any platform, and have an extra level of security use gpg, you will have to install it, and its harder to learn how to use (gpg requires you learn commands, but it is very powerful).

Thank you for your time,

Author Comment

ID: 9849614
i want to accept the reply of Arrummzen,but when i do it ,i get an error : "u could not accept this answer".

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