Cryptography Stack Exchange
Cryptography Stack Exchange

Questions tagged [attack]

A cryptographic attack tries to theoretically and/or practically attack the security properties of a cipher and/or algorithm.

A cryptographic attack tries to theoretically and/or practically attack the security properties of a cipher and/or algorithm.

The ultimate goal of a cryptographic attack is to convert ciphertext into plaintext, yet… every step towards that goal which reduces the security of a cipher can already be called a successful (theoretical) attack.

A capture-the-flag (CTF) contest may invite participants to find a secret text string, or flag, which is hidden in a deliberately vulnerable system.

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How was this 2048 bit number factored so fast?

I'm working on a CTF. The challenge is to get the contents of an encrypted message given the ciphertext and the 2048-bit RSA public key. I did finally get the flag after a few hours, but I'm still not sure why the first step worked. The first step…
rainbowkitty227
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Is there any famous protocol that were proven secure but whose proof was wrong and lead to real world attacks?

Are there moderns (post World War II) and famous protocols that were proven secure (in any model: game-based, UC...) but whose proof was wrong and could have led to real-world attacks? Note that: I'm not really concerned about attacks on the…
Léo Colisson
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Did a certain cryptography method get abandoned due to security flaws in the past?

I am researching how quantum computers affect current encryption methods (RSA and more). However, I remember learning in a course that there used to be a particular encryption method which was popular but suddenly had a very bad vulnerability in the…
Kevin Van Ryckegem
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How is encryption broken today?

There are often articles in the news that state that a certain country or hacker has been able to decrypt/hack highly protected systems: Some examples are the Lockheed Martin RQ-170 Sentinel that was downed in Iran and later said to be partly…
Quasar
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The aftermath and considerations of the new record of 30750-Bit Binary Field Discrete Logarithm - 2020

Granger et al. recently published a paper about breaking a record for discrete logarithm on the Binary field Computation of a 30 750-Bit Binary Field Discrete Logarithm, Robert Granger and Thorsten Kleinjung and Arjen K. Lenstra and Benjamin…
kelalaka
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What does a "real" quantum computer need for cryptanalysis and/or cryptographic attack purposes?

The cryptographic world has been buzzing the word "quantum" for a while now (even the NSA is currently preparing itself for a post-quantum crypto world) and quantum-related hardware engineering is evolving constantly. For example: the 5-qubit…
Mike Edward Moras
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How can C rand() be exploited if a secure seed is used?

I've just started doing a research project on CSPRNGs and I would like to know what kind of vulnerabilities a regular PRNG has with a secure seed. For example, if I generate a random number using LavaRnd to seed srand(), then generate some big key…
Jacob H
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The difference between these 4 breaking Cipher techniques?

I'm trying to understand the difference between the following and what they actually mean : Known plaintext attack Known ciphertext attack Chosen ciphertext attack Chosen plaintext attack Any clarification is much appreciated…
Scarl
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Why "1" in 51% attack on Blockchain network

In many sources, included Wikipedia, we read: Any pool that achieves 51% hashing power can effectively overturn network transactions, resulting in double-spending. My question is: Why do we talk about 51% attack? If my understanding is correct, we…
Manu NALEPA
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What is a multi-target attack?

What exactly is a multi-target attack? How does the attack work on different cryptographic schemes (block ciphers, hash functions, elliptic curves)? How can it be avoided?
Conrado
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Cracking a PRNG by observing ranks within groups of its output

Suppose that I am generating random numbers with Python's random module, so that there is a known random number generator (Mersenne Twister in this case). I've read: "[...] observing a sufficient number of iterations (624 in the case of MT19937,…
dcc310
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What is the malicious potential of a key-substitution-attack?

What is the idea behind a key-substitution-attack? We start from a given pair of message $m$ and signature $s(m)$. The signature can be verified by anybody in possess of the public key $y$: $v(m, s, y)= ok$ Now, by some mathematical magic (details…
MichaelW
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Why doesn't Wang's attack work on SHA-1?

Wang's (et al) differential attack works on MD5, MD4, RIPEMD and HAVAL. Why doesn't it work on SHA-1?
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How can I implement the elliptic curve MOV attack myself?

I understand and have implemented elliptic curve signatures in Python without the use of libraries like Sage, and would like to implement the MOV attack against certain weak types of elliptic curves. Even though I understand the mathematical…
Myria
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Relation between attack and attack model for signatures

What is the relationship between an attack and an attack model? For example, let $\Pi$ be the Lamport signature scheme. This signature has its security based on any one-way function. The Grover algorithm, an attack, inverts this function with…
juaninf
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