Questions tagged [attack]

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

Filter by
Sorted by
Tagged with
1
vote
1answer
78 views

Is there a benefit to "double encryption" when it comes to attacks analyzing attempted decryption results?

This is a beginner's question related to general security, but it fits cryptography exchange because it's more specific to the action of cryptographic attacks and how they work. Assume the following ...
1
vote
0answers
39 views

How does an attacker decrypt a hash function by looking for linearity?

Reading the selected answer to Designing a hash function from first principles rather than depending on heuristics is very insightful. The section on "nonlinearity" suggests that making ...
1
vote
0answers
92 views

SHA-256 Hash Crack

Suppose, If a SHA-2 hash does get broken completely with hardly any power, where would it get reported and is there currently a bounty on it?
1
vote
1answer
67 views

What is a differential attack on a hash function? How would one attack a SHA algorithm and what would achieve?

Currently, I have been assigned to attack a reduced version of SHA-1. What are we trying to achieve? How do we attack it?
1
vote
2answers
114 views

Using Shor's algorithm to access RSA messages without factoring

Most of the time people forgot that the real aim of the adversary against encryption is accessing the message. For example, in the RSA case, we talk about the factoring of the modulus to reach the ...
14
votes
1answer
5k views

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 ...
1
vote
1answer
49 views

Revealing original message length having random padding

If I have a message that has a fixed unknown length $L$, and we add to it's TLS encryption a random sized padding $0\leq n \leq N$ so the sent message if $L+n$. I'm also able to make the target re-...
1
vote
0answers
53 views

Cracking secret key, n, and m by hand with the Diffie-Hellman key exchange brute force

Problem: You see Michael and Nikita agree on a secret key using the Diffie-Hellman key exchange. Michael and Nikita choose $p = 97$ and $g = 5$. Nikita chooses a random number n and tells Michael that ...
2
votes
0answers
58 views

Short Nonces in ECDSA signature generation

Recently I noticed that my device generates short-sized Nonces. Approximately $2 ^ {243} - 2^{244}$. Could it turn out that there will be a small leak of ...
5
votes
1answer
1k views

Can a series of triangle reflections be used for cryptography?

(I guess no but why is this the case? Any way to make it possible?) Out of a given equilateral triangle T1 (with his 3 vertices A,B,C lying in a finite Field $\mathbb F_N^D $) another equilateral ...
4
votes
1answer
96 views

Would being able of factoring integers efficiently have some consequences over Elliptic Curve Cryptography?

Let's assume you can factor integers in a very efficient manner. Would that endanger the security of e.g. elliptic curve cryptography, or is there no link between the two ? You can often read that ...
0
votes
1answer
71 views

Eavesdropping attack on text-book RSA encryption with public nonce

Consider the following scenario: Alice has a secret key and public key pair for text-book RSA (denoted $\text{sk}$ and $\text{pk}$ respectively). Bob has an authentic copy of $\text{pk}$. The ...
1
vote
0answers
43 views

Can the salt be derived based on the other components of encrypted data?

I'm using python.cryptography's Fernet with PBKDF2 passphrase hashing to encrypt a piece of data (the value) that is stored, encrypted, in a database. The hashed passphrase is not stored in the ...
0
votes
1answer
42 views

How does knowing the factors of the key help me decrypt?

I recently started learning about cryptography and its Quantum aspect and I came across Shor's Algorithm (which solves the following problem: "Given an integer N, find its prime factors"). I ...
0
votes
0answers
23 views

What are the main attacks that can be done against a ZK Σ-protocol like Schnorr's identification scheme?

I heard about the "Chess Grandmaster Problem", Eavesdropping attacks and Man-in-the-middle. Can they be applied in any way to a ZK protocol? I'm not looking for long examples, just what are ...
2
votes
1answer
77 views

kleptography SETUP attack in ecdsa

I'm trying to implement kleptography SETUP attack of ecdsa with python. Just a simply script to verify the algorithm. However i can't get the right output as the paper said. Where is the problem? Can ...
0
votes
0answers
37 views

MAC Security - MAC verification queries

In the applied cryptography book by Boneh and Shoup, Chapter 6 on MACs, it is stated that an adversary that is also capable of requesting the challenger for verification queries (in addition to ...
4
votes
2answers
143 views

What would be the requirements for a new-age cipher standard?

While nowhere near being broken, AES has known attacks like reading from the substitution table, memory-based attacks, etc. If we keep getting better at breaking ciphers and we eventually get close to ...
0
votes
1answer
58 views

rsa attack with plain text, cypher text , public key

starting from the fact that there are different attacks on RSA, based on the starting situation, for example there are different studies, on attacks that find the private key having the freedom of an ...
0
votes
1answer
81 views

Chinese remainder theorem in ECDSA for parameters in secp256k1?

It is known that it is possible to apply the Chinese remainder theorem and attack RSA under precise conditions. https://tls.mbed.org/public/WSchindler-...
2
votes
1answer
438 views

breaking RSA with linear padding using Hastads attack with e>=11

I have been playing around with Hastad's broadcast attack on RSA with linear padding. Using the implementation and the test function from here: https://github.com/0n5/CTF-Crypto/blob/master/RSA/...
0
votes
0answers
28 views

Slide Attacks and FPE

What is a slide attack? I am not able to comprehend how they are used for attacks on FPE schemes like FF3.
0
votes
1answer
81 views

Can I copy digital signature for malicious purpose?

I am reading Cryptography. I have multiple questions to ask. I signed my QR code with my private key so that people can verify it's mine. QR code has data which is public. I have this QR code on my ...
0
votes
0answers
19 views

Crypto Economic Attacks such as Nothing At Stake and Sandwich Attack from Archive Nodes on Polkadot

Could you please advise me if there are threat vectors from archive nodes such as front running attacks, sandwich attacks and nothing at stake attacks as they are quite powerful in terms of the ...
0
votes
0answers
20 views

Linking attacks on anonymized data

I'm working on a anonymization project and I got interested in linking attacks. For simplicity I only look at data in table format, such as xlxx or csv data. To anonymise such data the most common ...
0
votes
1answer
97 views

How to generate large integer private key for creating CTF challenges?

I am trying to create a RSA CTF challenge, exposing $n$, $e$, $c$, and $d$. I have set $e=65537$ and $n = p * q$ where $p$ and $q$ are large primes each with 300 digits. I have determined $c=m^e \mod ...
1
vote
0answers
44 views

Impact of partitioning oracle attacks on file encryption?

I've just learned about partitioning oracle attacks recently, and I would like to clarify some things that are a little foggy to me right now. According to this thread, The aim is the recovery of a ...
2
votes
2answers
228 views

Time Complexity of Exhaustive Search Algorithm

I have the sets $S_1=\{2,10,20,6\}$ and $S_2=\{25,26,20\}$ and I want to find which numbers sum to make 32. This is very easy by inspection; 6 and 26. It seems similar to the Knapsack problem, but I ...
3
votes
1answer
89 views

Factorization of polynomial in GF(2^128) used in GCM

It is widely known, that using a GCM nonce twice or even more often can be used to disclose the authentication key H. I understand, why this is theoretically possible. However, I have no feeling about ...
1
vote
1answer
181 views

Why using same nonce (IV) twice voids confidentiality of plain text or even key?

I understand roughly (without details of GF algebra) the scheme of GCS/GMAC: IV is to be put into Counter-0, so initializing counters. It is known, that using a IV twice can not only reveal the plain ...
2
votes
1answer
69 views

What happens if the Edwards curve isn't quadratic twist secure?

On this webpage, Daniel Bernstein offers that the curve must be quadratic twisted secure. This means that if the curve has $\#E$ points on $Z_p$ where $\#E=p+1-t$, then the quadratic twist curve has $\...
2
votes
1answer
167 views

Can you please explain how Manger's attack against RSA OAEP works?

I searched but found nothing except the original paper, and I can't wrap my head around it. Can you help me by giving an overview and then if possible, a short explanation of the algo?
2
votes
1answer
70 views

Is generalized birthday attack only suitable for the problem with multiple solutions?

In David Wagner's article A Generalized Birthday Problem, he said and I quote: Our algorithm works only when one can extend the size of the lists freely, i.e, in the special case where there are ...
1
vote
2answers
786 views

So is AES-256 more secure or less secure than AES-128 after all?

It seems there are attacks that work more effectively on AES-256 than AES-128, which makes it less secure in some cases. But the bigger key size should add some safety margin on the other hand, for ...
0
votes
1answer
50 views

Domain Keys Identified Mail (DKIM)

If a company uses Domain Keys Identified Mail ("sender adds a special signature which includes author name / date signed by RSA Private Key. Receiver verifies the signature by looking up the ...
1
vote
2answers
323 views

Crack AES encryption via passphrase dictionary attack?

How easy would it be to crack a AES-256 encrypted file, that is protected by a passphrase? I understand that the trying to brute force a AES-256 encryption key would be on the unfeasible side, even ...
30
votes
1answer
5k views

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 ...
2
votes
0answers
82 views

Howgrave-Graham lattice attack on NTRU

I am lookin for a good example to illustrate this attack on NTRU using low parameters but I failed to do that, The attack consist to use LLL reduction on A basis of NTRU Lattice, let us use the column ...
2
votes
1answer
85 views

How to use sagemath to find nonlinear invariants of S-box?

I read a paper about a nonlinear invariant attack that is "Nonlinear Invariant Attack: Practical Attack on Full SCREAM, iSCREAM, and Midori64" And I've found a website of sagemath : https://...
1
vote
0answers
99 views

Vulnerability in DES3 when key can be chosen

In the question there are two functions encrypt basically does IV ⨁ DES3(P⨁IV) and encrypt_flag just encrypts the flag after being padded into a multiple of 8. IV is a random 8 byte number which is ...
1
vote
1answer
44 views

Quadratic Equations to Describe SBox

I am using a 8 bit Sbox having 16 entries with a lookup table of 4x4 in cryptographic algorithm. Sbox is constructed on subgroup of galois field 2^8. I want to calculate number of quadratic equations ...
2
votes
1answer
47 views

Choosing rings for PLWE

In [ELOS15], the authors give an attack on RLWE, and claim that "the hardness of Ring-LWE is... dependent on special properties of the number field" chosen; whereas, responding to prior ...
1
vote
0answers
54 views

Is there a complete summarized list of attacks on Diffie Hellman?

Is there a complete summarized list of attacks on Diffie Hellman? In RSA, there is https://crypto.stanford.edu/~dabo/papers/RSA-survey.pdf, so I was wondering if there is such a list somewhere. I have ...
0
votes
1answer
81 views

Is it possible to alter the plaintext message without altering the ciphertext?

Is it possible to alter the contents of a plaintext message without altering the ciphertext? Altering the private key is allowed to accomplish this. If the answer is yes, how would I go about in doing ...
2
votes
1answer
61 views

Dishonest verifier running a concurrent zero-knowledge protocol

Suppose Alice and Bob are engaged in the graph 3-colorability Zero-knowledge protocol in which Alice permutes a coloring $\varphi:V\rightarrow \{1,2,3\}$ for a graph $G(V,E)$, and then sends a ...
6
votes
2answers
299 views

Examples of Weak Cryptography being exploited in the wild by cybercriminals?

As a theorist, I often motivate the need for strong cryptography via simplistic methods, such as "If this did not exist, your online bank transactions would be vulnerable". This is of course ...
0
votes
1answer
64 views

Why is $\phi(N) = (p^2 -1) (q^2 - 1)$ here?

I was reading a paper on attacks on RSA variants, and the paper equates $\phi(N) = (p^2-1)(q^2-1)$. Before, I have always seen $\phi(N) = (p-1)(q-1)$ and don't understand why it is different here. I ...
1
vote
2answers
281 views

Is it possible to unscramble a scrambled ed25519 SSH key?

Let's say I generate an ed25519 SSH key with ssh-keygen -t ed25519. Then I take the private key file and randomly scramble the order of base64 encoded characters. ...
4
votes
1answer
130 views

Is there any correlation in between two AES with a key differ only by one bit? (ECB mode)

Given two AES (128bit, ECB mode) with almost equal keys $k_1,k_2$: 127 of the 128 key bits are equal. Is there any correlation in between the ciphers they build? $$AES_1(m_i) = c_i$$ $$AES_2(m_i) = ...
2
votes
1answer
96 views

basic question regarding two-time pad attack

Dan Boneh's Crypto 1 Course includes a lesson on stream ciphers with the following slide: He asks the question: And the answer he gives is $m \oplus p$, which is why this is insecure. But I don't ...

1
2 3 4 5
8