Usual way to hide jpegs. Extraction off application jpgs??

[markus]

I have an application that I think was developed using some form of
Borland C with a folder for BIG images with the extension .fre. When I
try to view them they cannot be read even by changing the extension
to jpg, bmp, zip, etc.

I also used some utilities for resource extraction with no success.

I know the images are there and there has to be a way to show and
convert them to a known format. I have seen libjpeg.dll and zlib.dll
in the main application folder along with other dlls.

Please suggest some utility or tell me the way developers usually hide
application jpg images (not icons, etc).

Thanks

 

[Malcolm]

Please suggest some utility or tell me the way developers usually > hide

application jpg images (not icons, etc).This isn't really on topic for clc. The best bet is to examine the file in a
hex / ascii combined view editor and see if you can make sense of the data,
then write a program to extract it. However if the developer really doesn't
want you to access the images then he will encrypt them and it is skilled
reverse engineering job to break the protection.

 

[Infophreak]

Have you tried the Unix utility called "file"?

 

[Kenneth Brody]

I have an application that I think was developed using some form of
Borland C with a folder for BIG images with the extension .fre. When I
try to view them they cannot be read even by changing the extension
to jpg, bmp, zip, etc.

I also used some utilities for resource extraction with no success.

Changing the filename doesn't change the format of the file. If the
file isn't in jpg, bmp, or zip format, changing the extension isn't
going to do anything except confuse things.

What is a ".fre" file? What format is it in? Do you have any programs
that know how to read such files?

I know the images are there and there has to be a way to show and
convert them to a known format. I have seen libjpeg.dll and zlib.dll
in the main application folder along with other dlls.

Please suggest some utility or tell me the way developers usually hide
application jpg images (not icons, etc).

Who said they were jpg's?

 

[markus]

..fre seems to be just a way to disguise the file since this extension
does not appear even in comprehensive Internet lists of file
extensions.

I know that changing the extension to a known format does not convert
the file itself but sometimes file readers can't read a particular
image with different than expected extension just because of the
extension even though the format may be well known and readable.

 

[Darrell Grainger]

I have an application that I think was developed using some form of
Borland C with a folder for BIG images with the extension .fre. When I
try to view them they cannot be read even by changing the extension
to jpg, bmp, zip, etc.

I also used some utilities for resource extraction with no success.

I know the images are there and there has to be a way to show and
convert them to a known format. I have seen libjpeg.dll and zlib.dll
in the main application folder along with other dlls.

Please suggest some utility or tell me the way developers usually hide
application jpg images (not icons, etc).

As a developer I have numerous ways of encrypting data. I can use a simple
Caesar cipher. I can reverse the data. I can flip the bits. I can store it
as char in memory but read/write it as long on a little endian machine
(flips every four bytes). The options are limitless.

Typically, performance and my imagination are the only things limiting how
I can encrypt the data. Obviously, I'm going to pick a method that is easy
to decrypt but that will not be obvious to someone looking at the data.

If might even encrypt the header information differently then the body. Or
I might just encrypt the header and leave the body unaltered.

Are you getting the idea? There is no standard way to do this. Being
non-standard is part of the security. Mystery makes your job harder so I'm
going to pick something that I have not seen before or I'm going to
combine two methods I have seen before to come up with something new.

More importantly, why would the developer use a non-standard format for
their image data? Could it be that they don't want you to decrypt the
images? By helping you wouldn't I be hurting the developer? Why wouldn't I
want to help the developer by not helping you?

I would hope that other developers would respect my choice to encrypt the
data and not help someone steal my images.

 

[Malcolm]

I would hope that other developers would respect my choice to encrypt >

the data and not help someone steal my images.That's only one reason for not using a standard format. The developer might
simply want the convenience of packing all images in one file. Or if he is
writing a game or an educational program he might want to prevent users from
viewing the images before the intended time in the program.

 

[markus]

Technically, by decrypting the images I am not stealing anything since
they are, so to speak, "mine" too. The are a series of maps
distributed on CDROM by the government. That is, I have already paid
the developer for them: as a tax-payer and as a CD-ROM buyer.

I know there can be many ways to encrypt the files but since there is
no BIG reason to go to great lengths with the encryption I tend to
think it is just a casual very simple disguise, whick I am trying to
determine.

I am sure they are images since they are in a folder called maps with
names corresponding to maps seen within the application.

When I developed applications in Qbasic there were libraries of images
that could be accessed within the aplication. In this case teh folder
has many images. it is not a library of images but separate files.
Maybe there's no standard way but there has to be at least a couple of
USUAL ways to do that and some form of viewer to bring them up.

I used a multiformat viewer that could not open them.

 

[Severian]

Technically, by decrypting the images I am not stealing anything since
they are, so to speak, "mine" too. The are a series of maps
distributed on CDROM by the government. That is, I have already paid
the developer for them: as a tax-payer and as a CD-ROM buyer.

I know there can be many ways to encrypt the files but since there is
no BIG reason to go to great lengths with the encryption I tend to
think it is just a casual very simple disguise, whick I am trying to
determine.

I am sure they are images since they are in a folder called maps with
names corresponding to maps seen within the application.

When I developed applications in Qbasic there were libraries of images
that could be accessed within the aplication. In this case teh folder
has many images. it is not a library of images but separate files.
Maybe there's no standard way but there has to be at least a couple of
USUAL ways to do that and some form of viewer to bring them up.

I used a multiformat viewer that could not open them.

There are many thousands of image and map formats, most of them
proprietary.

You might want to try the newsgroup sci.image.processing. This is
definitely not a C programming issue.

E-mail me if you would like me to take a quick look at a couple of
samples. I am familiar with hundreds of image formats and some vector
formats.