5 ms·

Novelty aside, if you encrypt to the same image, what was the point of encrypting? Can you hide something in the metadata that wouldn't have been visible until

Novelty aside, if you encrypt to the same image, what was the point of encrypting? Can you hide something in the metadata that wouldn't have been visible until decryption?

yincrash 12y ago
The visual image is the same, but the actual file is different. It basically stores a reverse encrypted (decrypted) version of the image as appended junk data.
- yincrash 12y ago
  You can confirm this by diffing the resulting file.
- Pxtl 12y ago
  Aww, that means you can't loop the process. OCR the text, run it, repeat.
diafygi 12y ago
The technique allows encryption from one image to another (doesn't have to be the same). I just made both images the same for fun.
- deleted 12y ago
  [deleted]
gfosco 12y ago
This would be a great form of Steganography. [1] Obviously, not having it return the same image, but something different. Encrypting a given file into a valid image file (like a meme.) It would pass by many things without raising suspicion, and require private knowledge (key, iv) to recover the alternate payload. It might even be plausibly deniable. [1] http://en.wikipedia.org/wiki/Steganography http://en.wikipedia.org/wiki/Steganography
- deleted 12y ago
  [deleted]
- yaur 12y ago
  One challenge here is that some services will mess with uploaded images. For example an image I created at one point for a puzzle got messed up because the image host was smart enough to figure out that multiple pallet entries were mapped to the same color and removed/remapped the redundant entries. This saved a ton of image size with no visual difference. Undecodable junk after the end of an image is also in the "can be safely removed" and so may not survive being transmitted via an image host or even email.
  - laumars 12y ago
    That might also work in its favour as how would an eavesdropper know that the same png on cloud a marked clean would exist on cloud b with a secret message encoded? They'd have to assume that each instance of the same meme is unique and that significantly reduces the effectiveness of automated search tools.
- xentronium 12y ago
  To be honest, rarjpegs (rars attached after jpeg file contents, properly unarchives by any software) have been used in the imageboards for a long time and are super-simple to create (cat file.jpg file.rar > file.jpg). It's actually rather interesting, if someone attaches some illegal content into rarjpeg, will it automatically make you a criminal after you see it (and store it onto your hard drive)?
  - robobro 12y ago
    Talking about illegal information is an inherently difficult task because illegal information is, as I see it, an illogical concept. With time, we can only hope that laws regarding information transmission loosen up. Familiar with http://en.wikipedia.org/wiki/Illegal_prime http://en.wikipedia.org/wiki/Illegal_prime ?
    - 12y ago

Novelty aside, if you encrypt to the same image, what was the point of encrypting? Can you hide something in the metadata that wouldn't have been visible until decryption?

yincrash 12y ago

The visual image is the same, but the actual file is different. It basically stores a reverse encrypted (decrypted) version of the image as appended junk data.

yincrash 12y ago
You can confirm this by diffing the resulting file.
Pxtl 12y ago
Aww, that means you can't loop the process. OCR the text, run it, repeat.

diafygi 12y ago

The technique allows encryption from one image to another (doesn't have to be the same). I just made both images the same for fun.

deleted 12y ago
[deleted]

gfosco 12y ago

This would be a great form of Steganography. [1] Obviously, not having it return the same image, but something different. Encrypting a given file into a valid image file (like a meme.) It would pass by many things without raising suspicion, and require private knowledge (key, iv) to recover the alternate payload. It might even be plausibly deniable. [1] http://en.wikipedia.org/wiki/Steganography http://en.wikipedia.org/wiki/Steganography

deleted 12y ago
[deleted]
yaur 12y ago
One challenge here is that some services will mess with uploaded images. For example an image I created at one point for a puzzle got messed up because the image host was smart enough to figure out that multiple pallet entries were mapped to the same color and removed/remapped the redundant entries. This saved a ton of image size with no visual difference. Undecodable junk after the end of an image is also in the "can be safely removed" and so may not survive being transmitted via an image host or even email.
- laumars 12y ago
  That might also work in its favour as how would an eavesdropper know that the same png on cloud a marked clean would exist on cloud b with a secret message encoded? They'd have to assume that each instance of the same meme is unique and that significantly reduces the effectiveness of automated search tools.
xentronium 12y ago
To be honest, rarjpegs (rars attached after jpeg file contents, properly unarchives by any software) have been used in the imageboards for a long time and are super-simple to create (cat file.jpg file.rar > file.jpg). It's actually rather interesting, if someone attaches some illegal content into rarjpeg, will it automatically make you a criminal after you see it (and store it onto your hard drive)?
- robobro 12y ago
  Talking about illegal information is an inherently difficult task because illegal information is, as I see it, an illogical concept. With time, we can only hope that laws regarding information transmission loosen up. Familiar with http://en.wikipedia.org/wiki/Illegal_prime http://en.wikipedia.org/wiki/Illegal_prime ?
  - 12y ago