# Tag Info

7

You first need to consider your adversary and what are your goals for this mechanism. This kind of mechanism appears less effective than proper cryptographic means: having secure PRNG means that both ends of the message exchange have access to some proper cryptographic means Adding noise means that the information exchange is less efficient: there is much ...

7

Some general advice about steganography: Much like in the physical world, the smaller what you want to hide, the easiest that goal is. Thus you may want to compress the payload(s), and treat the result as the new, smaller payload consisting of arbitrary bits. Because your payload consists of images, some lossy scheme such as JPEG or JPEG 2000 might be used ...

6

tl;dr: That depends entirely on the watermarking scheme. Longer version: That depends entirely on the watermarking scheme used, specifically on the perceptability and robustness of the watermark. If it's supposed to be visible and robust, degrading the quality as Dmitry Khovratovich suggested will retain the watermark but might achieve the effect he ...

5

If it's true that the origin of the copyright violation can be deduced, then each copy must be uniquely identifiable. My first idea would be to acquire multiple (unique) copies. Then: Compare the different copies frame-by-frame, pixel-by-pixel. For each pixel, output the median pixel value. This shouldn't degrade the overall quality at all. Whether this ...

5

A general theoretical answer to the title's What makes LSBit steganography detectable? is that in normal images, the LSBit of a pixel in some channel is correlated to higher-order bits in the same pixel and channel, that pixel in other channels, and adjacent pixels, in ways that mere replacement of LSBit tends to strongly alter. One simple way to improve ...

5

GIF images use look-up tables to store colours. If two entries in a table contain the same colour, then the pixels assigned to these colour values will be indistinguishable. For example, here is a one-bit-per-pixel GIF image. It started out as a black and white image, but I edited the colour table so that the white pixels also appear black: You can ...

4

Steganography is in general impossible, and most "practical" schemes do not work. If you are really interested in the area, however, there was some work done about a decade ago on provably secure steganography. It relies on an understanding of the distribution of the messages, which is what makes it very problematic in practice. Here are a couple of works ...

4

My understanding is that the three most popular approaches to "steganography using text as a cover" are: 1 Generate a completely new text by picking one word at a time from a dictionary, using the ciphertext bits to select which word. Pick words in ways that, at first glance, look like real English sentences, using Markov chain algorithms. Weihui Dai. ...

4

Quite often it is enough to prohibit spreading of the original content. If you “rip” the movie so that the quality loss would distort the watermark, it can be tolerated by copyright owners. They would know that anyone who would want the original quality will acquire the content legitimately.

3

The most famous text based steganographic scheme is the acrostic: using the first letters of words / sentences. If the mean sentence length is 15-20 words and mean word length is 5 letters, then efficiency is ~1%. You could use shorter than average sentences and/or words to increase the efficiency to within your bounds of >2%. Obviously this is a specific ...

2

It is because there is none. It doesn't matter, how low is the bitrate you encode, a detection algorithm specified against yours, will find it. And, for any detection algorithm, there is a such low bitrate (or steganography algorithm) which will remain below the radar. What is a more interesting question, which is the maximal bitrate / optimal algorithm ...

2

Your question is really too general - and perhaps off-topic, as steganography is quite a different field to cryptography. That being said, the answer to your question really depends on many things. Steganography is the art of hiding information in plain-sight. This information could be hidden in either; analogue or digital media, on the internet or in a ...

2

The Wikipedia example is something you probably would not really want to do, but does demonstrate just how much information you can add to a non-lossy image format without it being obvious to the human eye. Importantly, the technique used in Wikipedia only works for hiding a lower-quality image of the same dimensions as the container in the low bits of the ...

2

add noise to the cleartext to obfuscate the true text among a bunch of garbage .... I need an attacker to believe that the message is not encrypted So first of all, a small disclaimer. You realize that regular encryption standards would be much stronger and existing libraries are designed to handle data. On top of that it's generally not a good ...

2

In his answer Michael mentioned a known stego scheme of using the first characters of words/sentences as stego characters and rightly remarked that the scheme can be practically applied ("user-friendly") only when the stego character sequence is in natural language (i.e. not encrypted, in which case the scheme is however evidently very weak) and not when the ...

1

What you described is to use a so-called "stram cipher". Stream ciphers output a random sequence of bytes for the same Key/IV pair. The usual usage of stream ciphers is to XOR the data with the stream to obtain the encrypted data. You may want to follow the same approach by replacing the LSBs by the bits that were output by the encryption procedure (Data ...

1

The below is assuming a natural language is the one that has sentences from a well defined dictionary for that language (ex: oxford dictionary for english ). We can do this with the standard approach for FPE i.e $rank-encrypt-derank$. Build a $key-value$ pair map of all the words in the language of preference Where $key$ is the number and $value$ is the ...

1

I've developed one here: https://github.com/mjethani/typo In a nutshell, every 4 bits of the secret message is encoded as a typo in the stegotext. The value of the typo is the 4 least significant bits of the first byte of its SHA-256 hash. For example, the typo "infirmation" (information) carries the value 0xE (0b1110). The recipient simply identifies the ...

1

Passwords are commonly used for both authentication and encryption. Sometimes this is done securely. "Commonly" is an interesting word here, because passwords are commonly turned into encryption keys in ways that do not follow good security practices, and also passwords commonly do not have enough entropy to be suitable for generating encryption keys. ...

1

You tried interpreting this as a ternary code written in columns, but why not in rows? It was really quite simple to solve. Here's the code I used: for n in ['110','012','111','120','112','001','011','012']: x = int(n,3) + 64 if x==64: x=32 print chr(x), and here's the answer:

1

Proof of security: Let (x_1, ..., x_n) be the messages you caught. Let (p_1, ...) and (q_1, ...) be three streams of random messages known to both communication partners. Let these be from a true random number source generating non-autocorrelated data. Let (n_1, ...) be another stream of data from the same source. Since there is no correlation, it is ...

1

Are there such things as standard "test vectors" for steganalysis? Not that I am aware of. How could I do this? Your best bet would be to look for steganographic systems that are out there (either software or a paper describing it). Implement those systems and see how your steganalysis method works. Then you can implement other steganalysis ...

1

Check out Chaffing and Winnowing and other Data Privacy stuff like k-anonymity etc from Data mining world http://en.wikipedia.org/wiki/Chaffing_and_winnowing

1

You could use a Cardano grille to solve the problem of steganography (not encryption.) Very difficult to identify or even detect, as long as care is taken when hand-lettering the final message. If the mask's letters are too dense, the language of the cover message needed to conform to those letters can get a bit tortuous. Also note the grille doesn't need ...

1

I'm assuming you're referring only to static image manipulation, as that's the common fear these days (terrorists are hiding data in eBay images!) But it's a mistake to think that images are the only potential carriers of hidden data. Data can hide wherever information moves, including audio files, DNS requests, TCP port knocking, error codes, URLs, ...

1

This is called steganography and while the example you give is not significantly better than just having the AES in a "text file" (because it would not look like an actual PNG file), there are algorithms for hiding information in a "cover" file. However, if you do not mean to hide the fact that you have encrypted something, using AES alone is normally ...

1

"Hiding" content in an image (or other medium, it's a general technique called steganography) can be done either in a very obvious way (a dedicated data block, called ancillary chunk, which does not form part of the image), or it can be more effectively hidden in the low order bits of the image, thus very subtly degrading the picture. Both methods can be ...

1

Brute forcing the password, since no useful cryptanalysis of ICE is known. I'm really more of a theory guy, so I don't know of any tools for this, but there are some resources that I've found. http://security.stackexchange.com/questions/1376/where-can-i-find-good-dictionaries-for-dictionary-attacks answers its title's question, and ...

1

With Steganography, we take a short message, and embed that into a much larger signal, with the goal being that someone seeing the larger signal cannot tell that there's the embedded message. Now, this larger signal (which might be JPEG, a handwritten message, or in your case, interpacket delays) has a natural distribution; one way of viewing the goal of ...

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