Cryptography Stack Exchange
Cryptography Stack Exchange

Questions tagged [visual-cryptography]

Encrypting images so that they can be decrypted without using a computer, e.g. by superimposing two random-looking images.

Visual cryptography is a method of encrypting images so that they can be decrypted without using a computer, e.g. by superimposing two random-looking images that combine to yield (something resembling) the original image.

One of the most well known visual cryptography techniques was described by Mori Naor and Adi Shamir in 1994, in the eponymous paper "Visual Cryptography". Their method is essentially a scheme for black-and-white images that allows the original image to be reconstructed by superimposing the (semitransparent) shares.

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What are advantages of chaos based image encryption methods over simply treating images as opaque bit strings?

For an exercise at uni I am tasked with optimizing the execution speed a chaos based image encryption algorithm 1. While I have taken an introductory class to information security, I never came accross chaos based encryption before and have been…
förschter
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How can you produce visual cryptography?

I would like to be able to "code" images such as the one seen here on Wikipedia. Is this generally produced with software, or does this require complex programming? Ideally, I would love to be able to batch encrypt images based on settings I…
MicroMachine
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Reusing message in One Time Pad

One of the main rules of the OTP is, that a key should never ever be reused. But if we use some commutative operation (XOR for example) for generating the cipher text, then I don't see any difference between the message and the key, so can we also…
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Apply visual cryptography to a video stream?

I read that there are different ways to apply visual cryptography. One is to generate two images that when overlapped provide the original image. The main issue of using this approach with a video is that I would need to generate those two images…
David
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The role of the dealer in visual cryptography

In visual cryptography schemes (VCS), there is special person called dealer. The dealer sets up the system, and the only one who knows about secret image. After encryption, the dealer distributes the shares to participants. My question is, the…
stranger
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Explanation of part of a visual cryptography algorithm

I have been working on a project involving visual cryptography and I am stuck with the following problem. My question is related to this paper, AN IMPROVED VISUAL CRYPTOGRAPHY SCHEME FOR SECRET HIDING, by R.Youmaran, A. Adler, A. Miri. Can someone…
Bukurie Shabani
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Extracting the hidden text off an image embedded with steganography

Is it possible for me to extract the hidden text off a stego-image without using the same application that the hidden text was hidden with. I used 5 applications that do steganography such as, SteganographyX, QuickStego, Xiao Steganography,…
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Can you explain “k out of n” from the VCS paper by Naor and Shamir

I am new to visual cryptography. I’ve just read the paper “Visual Cryptography” by Moni Naor and Adi Shamir and I'm stuck on the chapter about the “$k$ out of $n$” construction. I am aware that, on page 8, there is a step-by-step explanation on how…
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RSA Hastad's broadcast attack with large numbers

I understand the theory behind Hastad's broadcast attack. Namely if we have three encrypted messages with the exponent e=3: c1 = m1 mod n1, c2 = m2 mod n2, c3 = m3 mod n3 Then we can use the Chinese Remainder Theorem to find c = c1 mod n1, c = c2…
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Is there a possibility to apply Moni Naor and Adi Shamir's "visual cryptography" on text ( paragraph)?

[Instead of two images I want to consider two paragraphs(text) when combined should give me a secret message] In their algorithm, the image has been split into two component images. Each component image has a pair of pixels for every pixel in the…
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How can blockchain ensure uniqueness of a digital asset like a photograph?

If I take a picture with my beloved camera, the RAW file can be put into a blockchain, and thus it will have a unique hash. If that unique hash is ever spotted anywhere we know it's a copy of my photo. But if someone wants to steal my photo, they…
webjay
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Security of (2,2) Shamir's visual secret sharing scheme : How are the 2 shares random?

From the Visual Cryptography by Shamir and Noar. Let us take the pixel expansion as 2. Therefore, each pixel will be represented by 2 pixels (also called as subpixels) in a share. Since this is a (2,2) scheme, we will have 2 shares. In order to…
Priyanka Gupta
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Number of possible access structure with $n$ person

I want to count number of possible access structures in closed form(if possible) as a variable of $n$,the number of share holder. I have tried in several ways. Still no good progress. It is very hard to consider all cases and count it and I think…
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Algorithms of steganography

Recently I'm working on steganography and I want to know that what are the main steganography algorithms and how they work. I'll be happy if you help me. thanks.
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Why the light contrast of a set $\mathcal{E}$ of VCRG produced by an encryption scheme for a binary image B is defined as follows

In the paper “Image encryption by multiple random grids”, Shyong Jian Shyu, 42(7):1582-1596,· July 2009, the light contrast of a set $\mathcal{E}$ of VCRG produced by an encryption scheme for a binary image B is defined…
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