5 ms·

The great thing about steganography is that as long as information is expected to arrive unmolested and unchanged you can't defeat it - at least as long as encr

The great thing about steganography is that as long as information is expected to arrive unmolested and unchanged you can't defeat it - at least as long as encryption is used along side it. Lets say you have an image, maybe lena.jpg or whatever, it's difficult to find out whether the image contains a hidden message or is an 'original' or has even been degraded because people don't know how to use photoshop/gimp/mspaint or what have you. If you want to store that image on a public site to contact other people in your league of evil doers then the it's easy enough as long as you're following the same protocol, they know where to look, how to look and have the keys to make it not look like garbage. The problem lies in the destruction of the data. In the case of storing an image on a public site with a hidden message, even if that message isn't just LSB but maybe you're doing fun stuff in the frequency domain the site would need to degrade the image in a way that destroys the message. imgur already alters images but there are some techniques that work even when resolution is reduced or the format changes. At some point in the future you can bet your ass that there's going to be a country that implements mandatory filters on uploaded images that destroy any numerical data that could be encoded into them if it's uploaded by an anonymous user. It's too dangerous otherwise (lol). There are some papers on it that I haven't read yet which may provide a generic attack that preserves image quality but what about audio? Video? Typos in web novels, ebooks? The list goes on. You can hide your info anywhere. I'm waiting for a future where there's an addon for pgp that takes images as an input and outputs something that looks normal instead of just proudly stating you can't see what I'm saying haha. The best defense is one that isn't seen right?

aidenn0 8y ago
I am not a cryptographer; perhaps someone who is can comment on my thoughts here? The flip side is that standardized steganography is far less effective. If you write "FooSteg" that can embed messages in jpeg files, I can probably write "FooStegStripper" that can remove messages encoded with FooSteg. A counterargument is that it's trivial to write a steganography program if someone doesn't think you're using steganography, but it's much harder to not leave a statistical signal if someone is looking for (an unknown) stegnanography. Tools that are sufficiently good enough to defeat generic analysis are hard enough that the ease of which known steganographic tools are defeated becomes an issue.
- nobody271 8y ago
  The main thing is encryption. Before you write anything to the image you encrypt it. That way even if someone does manage to recover all of the bits that you write they still can't read them (because they're encrypted). So even standardized steganography will be as difficult to crack as the type of encryption that's used. But also, if you are encoding using the least significant bit (aka 1 bit per color channel per pixel) you can vary the order in which you encode the bits using the same password that is used for encryption. I've heard it's possible to detect least significant bit steganography using statistics (like we've noticed the red channel varies from neighboring pixels more than usual) but even if that is possible, and I absolutely have doubts about that, there isn't any way to recover the sequence of pixels or decrypt it.

aidenn0 8y ago

I am not a cryptographer; perhaps someone who is can comment on my thoughts here? The flip side is that standardized steganography is far less effective. If you write "FooSteg" that can embed messages in jpeg files, I can probably write "FooStegStripper" that can remove messages encoded with FooSteg. A counterargument is that it's trivial to write a steganography program if someone doesn't think you're using steganography, but it's much harder to not leave a statistical signal if someone is looking for (an unknown) stegnanography. Tools that are sufficiently good enough to defeat generic analysis are hard enough that the ease of which known steganographic tools are defeated becomes an issue.

nobody271 8y ago
The main thing is encryption. Before you write anything to the image you encrypt it. That way even if someone does manage to recover all of the bits that you write they still can't read them (because they're encrypted). So even standardized steganography will be as difficult to crack as the type of encryption that's used. But also, if you are encoding using the least significant bit (aka 1 bit per color channel per pixel) you can vary the order in which you encode the bits using the same password that is used for encryption. I've heard it's possible to detect least significant bit steganography using statistics (like we've noticed the red channel varies from neighboring pixels more than usual) but even if that is possible, and I absolutely have doubts about that, there isn't any way to recover the sequence of pixels or decrypt it.