zalgorithmic t1_jbb400v wrote
Reply to comment by DoktoroKiu in A group of researchers has achieved a breakthrough in secure communications by developing an algorithm that conceals sensitive information so effectively that it is impossible to detect that anything has been hidden by thebelsnickle1991
Isnt one of the main points of good cryptography to have the message already be indistinguishable from noise? Just build up enough entropy that it seems like noise unless you have the proper key.
Mechasteel t1_jbbh94i wrote
Cryptography is so when they see your message they can't understand it. Steganography is so they don't see your message. Shannon entropy is how much your message looks like noise, which is coincidentally the same as data density.
VoyageurEnNoir t1_jbdh595 wrote
No, it’s the same as information density, not data density.
Mindless_Consumer t1_jbc3kej wrote
Most (all?) Steganogeaphy can be detected.
For example, one technique is to hide data in a jpeg. Open the file it looks like a regular image. Run the binary through a decryption process, get a secret message.
We may not be able to crack the message. But we can find out it is there. Then hit you until you decrypt it.
ImmoralityPet t1_jbckhzb wrote
That's what they're saying the advancement is here. The presence of the message is undetectable. The alterations that are done to the image are indistinguishable from other probabilistic filters that the file type is typically subjected to.
Mindless_Consumer t1_jbcnplo wrote
If true - its actually a big deal.
Consider a hostile universe and we need to send a signal across the galaxy, the presence of a signal alone is enough information to get you xenocided. Being about to mask the existence of a signal will be vital.
ImmoralityPet t1_jbcqx9l wrote
That's not what they're claiming though. The presence of a signal is known. The presence of a second message embedded in the signal is what is undetectable because the encoding process is embedded in probabilistic filters that the signal was subjected to anyway. And the output signal is indistinguishable from a signal that went through such a filter with no embedded message.
Mindless_Consumer t1_jbcs38u wrote
Yea. So match the signal to that of a local star or some other natural phenomenon.
The point is - if this is impossible which it may be. Long communication in a hostile galaxy may be impossible. If it is possible an explanation for not detecting signals is they are hidden and undetectable.
CrispyRussians t1_jbddq3v wrote
I love that you went right to space travel. I don't think this is applicable but I like where your mind is at
Mindless_Consumer t1_jbdfyzb wrote
Yea, like, I thought we were on futurology.
CrispyRussians t1_jbdg2sf wrote
I think the sun focuses more on the next 50-100 years not the next 1000
Mindless_Consumer t1_jbdggmu wrote
Like I said - its a big deal.
If it is actually hard undetectable, this is how we're going to do it. That's pretty cool.
green_meklar t1_jbcyjm2 wrote
The problem with encrypted data that looks like noise is that noise also looks like encrypted data. If someone sees you sending noise to suspicious recipients, they can guess that you're sending encrypted messages. Governments that want to ban encryption or some such can detect this and stop you.
The advantage of steganography is that you can hide not only the message itself, but even the fact that any encryption is happening. Your container no longer looks like noise; it's legitimate, normal-looking data with a tiny amount of noisiness in its structure that your recipient knows how to extract and decrypt. It gives you plausible deniability that you were ever sending anything other than an innocent cat video or whatever; even people who want to ban encryption can't tell that you're doing it.
zalgorithmic t1_jbczvnb wrote
In my mind it’s best to do:
Data->compress->encrypt->steganography
Not saying steg is bad and cryptography is good, just that I don’t quite see how encrypting the data properly in the first place such that it shows up as some random distribution before embedding it with steganography is a wildly new concept.
If the distribution of encrypted data is that of noise, the image would just appear slightly noisy, especially if doing least significant bit shenanigans
green_meklar t1_jc51rar wrote
>I don’t quite see how encrypting the data properly in the first place such that it shows up as some random distribution before embedding it with steganography is a wildly new concept.
It's not. I was getting at the converse idea: Given your encrypted data, steganography allows you to hide the fact that any encryption is even being used.
>If the distribution of encrypted data is that of noise, the image would just appear slightly noisy
Only by the broadest definitions of 'noise' and 'appear'. The image does not need to actually have visual static like a dead TV channel. That's a very simple way of embedding extraneous data into an image, but not the only way.
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