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C# .jpg help pls

Name: Anonymous 2010-06-28 9:49

Can i get some help?
I am making a program in c# that hides strings into images by changing each pixel color to be odd or even so i can store binary data in the pixels without changing the over all look of the image. Its just something i am making for fun but it only seems to work with .bmp's. I want to get it working with .jpg but i dont know how to do this. Right now i am just using System.Drawing.Bitmap to modify the images. Is their any other way that i can do this so it will be compatible with .jpg?

Name: Anonymous 2010-06-28 9:53

Yes. Do that normally, then use Paint to convert it. Ignore any data loss you will get.

Name: Anonymous 2010-06-28 9:57

The data loss from paint makes it unreadable...

Name: Anonymous 2010-06-28 10:08

Okay. Now use any other image program to convert it to jpeg. Ignore any data loss you will get.

Name: Anonymous 2010-06-28 10:09

can i get some real help from some one?

Name: Anonymous 2010-06-28 10:12

>>5
Listen here, fuckface. You want to get the data back out of a lossy compression algorithm? Are you fucking stupid?

Don't use image/jpeg, you total moron!

Name: Anonymous 2010-06-28 10:12

You can't use C# for that, it isn't Touring-complete. You must use either Brainfuck or FIOC.

Name: Anonymous 2010-06-28 10:14

*snif snif* you dont have to be so mean about it... i just wanted .jpg cus i wanted to post on teh chan...

Name: Anonymous 2010-06-28 10:17

>>8
You don't have to be so mean.>>5
Back to /b/, please.

Name: Anonymous 2010-06-28 10:21

so no one is going to help me... *sad face*

Name: Anonymous 2010-06-28 10:22

>>10
Use a lossless image format

Name: Anonymous 2010-06-28 10:22

>>6
Are you saying a lossy compression algorithm can't be used to achieve lossless compression?

Name: Anonymous 2010-06-28 10:25

>>12
>>3 is, at least.

Name: Anonymous 2010-06-28 10:39

>>11
i tried png but it fails with png too...

Name: Anonymous 2010-06-28 10:40

>>14
Maybe it's you.

Name: Anonymous 2010-06-28 10:41

>>15
*sad face*

Name: Anonymous 2010-06-28 10:44

>>16
Please stop.

Name: Anonymous 2010-06-28 10:45

>>17
*sad face* awwssssssss....

Name: Anonymous 2010-06-28 10:47

>>8
You will need a library which handles jpeg format for this, and jpeg is compressed so you WILL lose a lot of data.

My advice: find a library which can handle png and use png instead.

NOW GET OUT!

Name: Anonymous 2010-06-28 10:52

>>19
gezz ... i didnt know /prog/ was soo mean...

Name: Anonymous 2010-06-28 10:52

HAHAHA
Image files are bloat.
Real programmers use text/plain, you faggot steganographist.

Name: FrozenVoid 2010-06-28 10:54

>*sad face*
there emoticons for that you know:
 u.u , v.v and >.<


__________________
Orbis terrarum delenda est

Name: Anonymous 2010-06-28 11:09

steganography with JPGs
But anyway, according to http://www.faqs.org/faqs/jpeg-faq/part1/section-13.html, even if you'd specify max quality (I believe that the default in .NET is 90% or 95%), the compression is not lossless.

Name: Anonymous 2010-06-28 11:10

>>1
This idea is rather stupid. For a start not all image formats use pixels, and you could just put the string straight in to the file somewhere (most likely an extension area) with a reasonable understanding of image specification.

>>6
The JPEG specification specifies both lossy and lossless methods of compression. On top of that, nobody said he is making his changes before compression- if you read in to it you could probably figure out some way to get your bits of information stored in what will become the decoded DCT matrix.

Name: Anonymous 2010-06-28 11:50

>>24
The JPEG specification specifies both lossy and lossless methods of compression.
That's the second time I've heard someone say that. Even if it were true (and it very obviously isn't), no software supports lossless JPEG.

Name: Anonymous 2010-06-28 12:16

>>25
Even if it were true (and it very obviously isn't)
http://www.w3.org/Graphics/JPEG/itu-t81.pdf
Page 132.
no software supports lossless JPEG.
It's in the standard- regardless of whether or not OPs ingenious string hiding technique will see widespread adoption. No software supports messages hidden in the parity of pixel data either.

Name: Anonymous 2010-06-28 12:27

>>26
>No software supports messages hidden in the parity of pixel data either.

One peace of software does, OPs.

Name: Anonymous 2010-06-28 12:28

>>27
That's not parity.

Name: Anonymous 2010-06-28 13:04

>>25
Did you even read the file you were linked to? There's no difference between decoding lossy and lossless jpeg.

Name: Anonymous 2010-06-28 13:19

>>28
You're right. It's a
QUOTE FAILURE

Name: Anonymous 2010-06-28 13:23

>>29
Did you even read the file you were linked to?
Try again.  Lossy and lossless jpeg are completely different algorithms.

Name: Anonymous 2010-06-28 13:37

>>29
You're attacking >>25 for not having read >>26 before posting >>25?

Name: Anonymous 2010-06-28 14:29

ATTACK MY ANUS

Name: Anonymous 2010-07-01 10:36

http://news.yahoo.com/s/livescience/20100630/sc_livescience/russianspieshidsecretcodesinonlinephotos

Although the exact details of what the supposed Russian agents embedded in the pictures, and how they did it, remains classified, the basic technique involves changing the numeric code that computers assign to colors, explained Tal Malkin, an assistant professor in Columbia University's cryptography laboratory.

To generate the picture on a computer screen, the computer assigns every pixel three numeric values that correspond to the amount of red, green or blue in the color the pixel displays. By changing those values ever so slightly, the spies could hide the 1's and 0's of computer language in the picture's pixel numbers, but without altering the picture's appearance to the human eye, Bellovin said.


back to /russia/, please

Name: Anonymous 2010-07-01 10:47

>>34
The cute spy chick[1] was caught because you assholes decided that it's more interesting to troll each other than to help her with her steganography program in C#. Was it worth it?

-----
[1]: http://i.imgur.com/7qHLg.jpg

Name: Anonymous 2010-07-01 11:11

>>35
If you're not competent enough on your own to do your /job|homework/, too damn bad.

Name: Anonymous 2010-07-01 11:22

First off, the authorities don't know to analyze a normal looking picture for secret data, said Malkin. And second, with so many pictures on the Internet, the photos containing hidden messages can hide with the safety of numbers.
trollface.txt
Seriously, they don't think that the FBI or NSA or CIA have any way to detect that an image has been edited? Or that they don't have the computing power to scan images? Shit, some random company can come along and make an image search engine like tineye, I'm sure the three-letter agencies have the ability to make a steganography search.

Name: Anonymous 2010-07-01 11:37

>>37
Seriously, they don't think that the FBI or NSA or CIA have any way to detect that an image has been edited?
I find it scary to think that the NSA have so much information about information in general that they could actually do this.
(Like what an alleged NSA employee said, that there's a way of distinguishing encrypted and random data)

But then the article says stuff like
But back then, it was only a theory.

Name: Anonymous 2010-07-01 12:08

>>38
(Like what an alleged NSA employee said, that there's a way of distinguishing encrypted and random data)
Only idiots aren't able to devise undetectable steganographic methods. They deserve to get caught.

Name: Anonymous 2010-07-01 12:16

>>1
You should be using FrozenVoid's crypteria algorithm.

Name: Anonymous 2010-07-01 12:35

>>40
That was the worst code i've ever seen. No indentation, no order, only one comment.
http://frozenvoid.blogspot.com/2009/07/crypteria5c-cipher.html

Name: Anonymous 2010-07-01 12:43

>>41
Welcome to /prog/.

Name: Anonymous 2010-07-01 12:45

#define chp char*
#define ucp unsigned char*

Oh my. That's two problems waiting to happen.

Name: Anonymous 2010-07-01 12:59

sharples

Name: Anonymous 2010-07-01 13:10

>>44
*seshurp

Name: Anonymous 2010-07-01 13:52

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Name: Anonymous 2010-07-01 13:56

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Don't change these.
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