Cryptography Stack Exchange
Cryptography Stack Exchange

Questions tagged [cryptanalysis]

Analysis of individual security aspects of a cipher or algorithm, not the security of a cipher or algorithm in general (which would lean towards “algorithm-design”).

Cryptanalysis is the analysis of cryptographic algorithms with the aim of finding weaknesses, which allow attackers to "break" them. For ciphers, the aim is to get the key or plaintext, for hashes it is to find collisions or preimages, for signatures/MACs it is to create forgeries. Methods include differential, linear and algebraic cryptanalysis.

Use this tag for Q&As related to the analysis of individual security aspects of a cipher or algorithm, not the security of a cipher or algorithm in general (which would lean towards ).

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Why are bitwise rotations used in cryptography?

Any understanding I have of cryptography stops right around the cipher level. As such, I'm just curious as to why bit shifts and moreover circular bit shift are so prevalent in cryptography.
Jeff
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Will cryptanalysis always stay a relevant topic?

I hope this doesn't look like a silly question. In an age where our current cryptography is often impossible to crack when properly implemented and used, would we be able to decipher anything, for example if WWIII were to break out ? Similarly to…
Katoptriss
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Source for examples with broken cryptography

I've heard again and again that many crypto systems have been broken in the past for one reason or another and that it is best to use one that has been peer reviewed, etc etc. However, I've yet to see a source (website, book) that gives information…
Gustavo Litovsky
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CPA vs CCA attack of an encryption scheme

Semantic Security is a concept that made New Cryptography, (that is Cryptography invented after 1975) into a rigorous science. It connected old cryptography (that is Shannon's information theory-based cryptography) to New Cryptography. Suppose that…
Istvan Simon
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What are some good examples of modifying crypto where flaws are not really obvious?

I run into some developers from time to time who sometimes try to modify crypto which I end up saying along the lines of "Don't modify crypto." Usually, the question I get is - "OK, tell me why is this bad? How can this be broken?" My rule of thumb…
TheRookierLearner
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Analysis of Repeatedly Enciphered Plaintext using Same Algorithm / Key?

Please forgive the impracticality of this question, but I'm curious about the behaviors of encryption algorithms applied to their own output. Suppose I have an encryption algorithm E and (using the same key(s)) I repeatedly encrypt its output for a…
Michael Petito
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McEliece post quantum cryptography

Can someone explain me in basic simplistic english if possible how does McEliece asymmetric encryption works and why its quantum safe ? Thanks in advance.
Glenn Camilleri
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If a cryptanalytic breakthrough is made, what process should be followed?

If a researcher manages to make a cryptanalytic breakthrough on a cryptographic algorithm or protocol that is in use, what should they do? Has this ever happened before? What are the implications for release and how do those relying on such systems…
Arlen Beiler
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Correlation Immunity Of 4 bit S Box

I have a 4 bit S Box byte[] S = new byte[16] { 0x9, 0xE, 0x5, 0x6, 0xA, 0x2, 0x3, 0xC, 0xF, 0x0, 0x4, 0xD, 0x7, 0xB, 0x1, 0x8 }; How can i calculate Correlation Immunity of this S Box
vinu
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The chi-square test for cryptography

I have a question about the chi-square test How can we use it in cryptography? And what results should we expect from it when a file is encrypted? I mean, when a file is encrypted, should its value increase?
ph9675
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Understanding one-way hash functions construction

I understand the needs that lead to the development of cryptography and I am quite familiar with the uses we make of the cryptographic tools. But, as a programmer, I am conditioned to see them as "black boxes" with specific properties. To me, SHA-X…
Rerito
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Big data and modern crypto systems

Throughout history, some cryptographic systems were broken by finding patterns in encrypted messages (like frequent chars in a particular language), and thereby discovering the cipher. These classic systems, which relied on algorithms unknown to the…
Diego
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Cryptosystems defined over the real numbers

In a computational setting it is clear that we cannot do computation over the real numbers, as we couldn't generate, much less store them, so we have to instead deal with numbers that approximate them. If a cryptosystem has some component defined…
user918212
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What is the approximate effort to break one additional round of a primitive?

Many of the cryptographic primitives currently in use have a number of their rounds already broken. Generally and with no particular primitive in mind, what is the scale of the effort to break one more round? Is is anything like $O(n)$, or more…
Paul Uszak
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Is it possible to make sense of an unknown language by means of cryptanalysis?

I was wondering if it was possible to make any sense from an unknown language by using cryptanalysis. My premises are: suppose an analyst that knows nothing about a language (let's suppose chinese but it can be any other as long as it totally…
mrbolichi
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