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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”).

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-2 votes
4 answers
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Can linear congruential generator be used in public-key cryptography?

The question is not about generating pseudo-random numbers with linear congruential generator. I'm exploring the possibility of using a Linear Congruential Generator (LCG) in the context of public-key ...
Ivan Stepanov's user avatar
0 votes
0 answers
22 views

Can Index of Coincidence be used for ciphertext containing letters, numbers, and symbols? (All characters in cipher are from ASCII table)

I have been trying to figure out how to approach performing cryptanalysis on the following ciphertext, but am stumped on whether I can use classical techniques such as IoC to derive useful information ...
William LoCascio's user avatar
2 votes
0 answers
66 views

Cryptanalysis of xorshift + multiplication mixer

Suppose we have a $2w$-bit integer $s$, a $2w$-bit odd round key $k$, and some constant $c$ then we can define the following permutation: ...
orlp's user avatar
  • 4,310
1 vote
1 answer
119 views

Could this method allow two people using weak cryptography to bootstrap their way to unbreakable cryptography (e.g. otp)

Encryption schemes are usually explained to the general public in terms of "time required to break" where strong encryption like AES-256 should in theory take millions of years. Given that ...
user avatar
0 votes
0 answers
52 views

How to find openSSL's AES T-table location for cache side channel attack

Let us assume I have a physically-indexed last-level cache, which is shared between the victim and adversary. Both the victim and attacker have their own copy of openSSL library in the caches. Victim ...
nivedita's user avatar
4 votes
1 answer
188 views

How to prove the conclusion " linear operation $\mathsf{XOR}$ does not affect the division property"?

Division property is proposed as a generalized integral property at Eurocrypt 2015 by Yosuke Todo in his paper Structural evaluation by generalized integral property, And in paper Integral ...
L0ngx1ng's user avatar
  • 143
1 vote
0 answers
88 views

Is generating random blake256 hashes until packed points is on the curve, a safe algorithm to avoid the discrete log between the generated points?

I know there’re many questions that ask how to safely HashToCurve, but I want to know if the method I found in an actual implementation is secured against the ...
user2284570's user avatar
2 votes
2 answers
159 views

Lemma 5 in Matsui's Paper about Linear Cryptanalysis

I have a problem about the formula in Matsui's paper about linear cryptanalysis. Let $N$ be the number of given random plaintexts, p be the probability that equation $P[i_1,i_2,\cdots,i_a]\oplus C[...
35 honglang's user avatar
0 votes
1 answer
72 views

Getting the slope of a public key given its x and y coordinates

Is it possible to get the slope of a public key given its $x$ and $y$ coordinates? Since all the ECC calculations come from geometry, I thought this calculation might be possible.
Dev Tenji's user avatar
0 votes
0 answers
47 views

I'm curious on what the downsides of the public-key encryption method from my research project could be

As part of my final BS degree research project, I had to work with an encryption method based on research done in my university. What surprised me, is that while the method is very simple, I can't ...
H-a-y-K's user avatar
  • 125
0 votes
0 answers
25 views

Question about Environment Set in Universally Composable Security Proof

I have read into many papers and tutorials regarding "Universally Composable Security Proofs." I still have one confusion about the initial setup by the environment. On one hand, I got that ...
Novice User's user avatar
2 votes
1 answer
51 views

Question about Security proof of Gentry's Anonymous IBE

In Gentry's paper "Practical Identity-Based Encryption without Random Oracles", I have a little difficulty understanding the security proof part. The paper claims that in the Challenge phase:...
jhf's user avatar
  • 21
1 vote
0 answers
73 views

New Impossible Differential Attacks on AES reduce time complexity

I am interested in the following snippet from the paper New Impossible Differential Attacks on AES. Analysis of Steps 3–4 of the 7-Round Attack in the 8-Round Attack The most time consuming steps of ...
can balıkçı's user avatar
3 votes
0 answers
63 views

improved impossible differential crpytanalysis of 6-round rijndael

I'm studying the paper: "Improved Impossible Differential Cryptanalysis of Rijndael and Crypton". I've got two questions: Please explain the calculation performed for step 5? Step 4 ...
can balıkçı's user avatar
0 votes
0 answers
37 views

In the context of Hardware Security and Cryptography, how do I calculate the Algebraic Normal Form for sboxes [duplicate]

In our hardware security exercise, I am trying to calculate the ANF function manually (Sboxes) for the given table: And I came up with the result as: I thought I was calculating it correctly using ...
TorJaks669's user avatar
2 votes
0 answers
29 views

Can a differential attack on FEAL4 yield multiple valid keys?

For my version of this attack I used the FEAL4 version depicted here http://theamazingking.com/crypto-feal.php and in the book "Applied Cryptanalysis Breaking Ciphers in the Real World -- Mark ...
curious_cryptocopter's user avatar
9 votes
2 answers
642 views

Is NTRU broken?

Today a new paper appeared on ePrint, "Improved Provable Reduction of NTRU and Hypercubic Lattices". It claims that: this is the first provable result showing that breaking NTRU lattices ...
swineone's user avatar
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-1 votes
1 answer
72 views

Is security of Manuel Blum's Mental Hash function dependent on Security Through Obscurity for it's effectiveness?

I have been practicing using Manuel Blum's Mental Hash Function for personal use, described in the link below: Mental Cryptography and Good Passwords However, Rob Shearer has shown that the function ...
its.just.me's user avatar
0 votes
1 answer
56 views

Vulnerabilities of a word-level substitution cipher

What kind of attacks would be possible against this kind of substitution cipher? Every word in the plaintext is to be replaced with a random string of the same length The encryption of any given word ...
u2892's user avatar
  • 1
1 vote
0 answers
70 views

How secure is this hash combination function for merkle trees?

I am exploring the class of functions that I have seen called "hash combination functions". These functions are arguably distinct from hash functions, generally providing second-preimage ...
Justin Martin's user avatar
2 votes
2 answers
582 views

The future of cryptanalysis

I am an undergraduate (grade three). I am confused about the cryptanalysis. Because a lot people say that the modern ciphers are complete and they can't be cracked. Maybe the prospects for ...
Arthur Alexander's user avatar
0 votes
2 answers
51 views

Instantiation of norm bound in SIS

Recall Short Integer Solution: $\textbf{SIS}_{n, q, \beta, m}$: Given $\textbf{A} \in \mathbb{Z}^{n\times m}_q$, $\vec{b} \in \mathbb{Z}^{n}$, find $\vec{z} \in \mathbb{Z}^{m}$ of norm $||z|| \le \...
user avatar
1 vote
0 answers
59 views

Choice of algorithm for ECDLP when you have information regarding private key

Okay, I have a ECDSA public key $P$. The curve is arbitrary and not necessarily secure. The finite field of curve, $q$, is a $315$ bit prime. I know the following information regarding key: The ...
madhurkant's user avatar
0 votes
1 answer
69 views

Is using the polynomials ring $\mathbb{Z}_{2}[x]/(x^8+1)$ in RLWE secure against brute force attack?

Given the ring $R_2=\mathbb{Z}_{2}[x]/(x^8+1)$, initiate a public key encryption based on RLWE $(A,b=As+e)$ where all the parameters are selected as polynomials over the given ring. Under the ...
Anas Ahmad's user avatar
0 votes
1 answer
70 views

Can I prove AES-GCM nonce reuse just from the bytes?

I have AES-GCM output with GMAC tag. The plaintext consists of some bitfields I know the structure of. When I generate input which should only affect timestamps and counters in very specific bytes, I ...
nusch's user avatar
  • 1
1 vote
1 answer
67 views

Does encrypting a billion short and similar jsons with known structure make encryption less secure?

Let's say we have a billion short individual json files with same regular structure: {"name": "<name>", "id": <id>}. Each ...
aackmann's user avatar
0 votes
1 answer
122 views

How would I go about reverse engineering a hash function given input string and generated hash

I have a wireless capture of data and it's 12 bit hash. I am trying to identify the actual function that would have generated the hash data. I tried all the generic 12 bit CRC polynomials but none of ...
jay's user avatar
  • 1
3 votes
1 answer
185 views

equivalence between entropic perfect secrecy and single probability

i'm new to information theory. I know the standard perfect secrecy definition: $$ P(M=m|C=c) = P(M=m) , $$ for all $m$ and $c$, respectively the message and the cypher. Now, i can use the entropic ...
forgetfuled's user avatar
1 vote
1 answer
77 views

Is a Shift Cipher with Random Insertions Unbreakable?

Imagine an Encryption Algorithm which applies a classic Shift Cipher (also called Caesar or ROT-X) to a text (with only lowercase [a-z] and the space ...
v3l0c1r4ptx0r's user avatar
2 votes
1 answer
197 views

How to identify if a legacy encryption algorithm used in my programming language is secure?

I used an open-source programming language called Lucee / Cfscript that is closely related to Adobe Coldfusion. The default function that developers use to encrypt and decrypt data (usually for ...
ialexander's user avatar
15 votes
1 answer
1k views

Impact of Ryan and Heninger's CRYPTO 2023 paper on post quantum cryptosystems

From Schneier's blog, which seems to have been written in response to a somewhat recent Quanta magazine article: The winner of the Best Paper Award at CRYPTO this year (2023) was a significant ...
kodlu's user avatar
  • 23k
3 votes
2 answers
1k views

Can I change the radio frequency according to my encryption algorithm?

I know that information can be changed by changing the frequency of electromagnetic vibrations.My question is, can I change the frequency according to my encryption algorithm? That way I can get a ...
Hacer's user avatar
  • 33
0 votes
1 answer
70 views

Can HKDF be safely used as a round function in a Feistel Cipher

Hello my question is it practical to use HKD as a round function in a Feistel Cipher I know you should not roll your own crypto, this is for learning purpose's only. Take a look at my code and let me ...
dasein's user avatar
  • 3
2 votes
1 answer
129 views

Not understanding elliptic curve scalar multiplication to produce Ethereum address

This is the equation Public key = Private key * G Here, ...
Asif Iqbal's user avatar
-1 votes
1 answer
132 views

Given and encrypted message, is it theoretically possible to decrypt a message without the key or guessing it? If so, what methods could be used?

Decrypting an AES-Encrypted Message Without the Key: A Cryptographic Challenge Summary: I am investigating the possibility of decrypting an AES-encrypted message when the encryption key is unknown ...
NeoX's user avatar
  • 1
1 vote
2 answers
346 views

Is it faster to decrypt than to encrypt in all cryptography systems? [closed]

I am using a cryptography system in which the Feistel structure and permutation cipher are combined. I am amazed by the result; decryption is so much faster than encryption. My system is working ...
Dharmendra Thapa's user avatar
0 votes
0 answers
63 views

How to estimate the bias of linear cryptanalysis given the input and output masks

Assume the input linear mask is $a$, and output mask is $b$,for a block cipher $F$ with $r$ round,How to accurately and quickly estimate the bias of linear cryptanalysis? which is \begin{equation*} ...
HelloSpace's user avatar
1 vote
1 answer
112 views

Hard decisional problem on bilinear groups

Problem: Given $g, g^a, g^b, g^c \in G$ and an efficient bilinear map $e:G \times G \longrightarrow G_T$, distinguish $g^{abc}$ from a random element of $G$. Is it a hard problem?
Anna's user avatar
  • 11
0 votes
0 answers
196 views

Speed comparison of encryption algorithms

I am trying to compare various encryption algorithms in terms of encryption duration, decryption duration, information entropy, NPCR, UACI, and correlation coefficients. I used a Lena 256x256 ...
ysnky's user avatar
  • 1
3 votes
1 answer
160 views

Judgment of Results from NIST Randomness Testing

I am using the NIST suite to test the randomness of binary numbers and I have a 64KB dataset. I am confused with the results in finalAnalysisReport.txt. I have the ...
yuting zhang's user avatar
0 votes
0 answers
98 views

Finding plain text given two cypher texts of the same plain text with two different public keys

I want to find the plain text from two cyphertexts of RSA, encrypted with two different public keys. I know that: for $E((n,e),m) = c_0$ and $E((n,f),m) = c_1$ , $c_0^x \cdot c_1^y \bmod n = m \bmod n ...
dskrby's user avatar
  • 1
0 votes
0 answers
93 views

AES SBOX Masking in Python

I am trying to create an AES Sbox masking based on this paper. In the paper, they tried to mask the sbox described in this other paper. The inversion is been done in GF(4). I know that it is mostly ...
John's user avatar
  • 1
0 votes
0 answers
70 views

Differential cryptanalysis of modes of operation

It is not quite difficult to understand the idea of differential cryptanalysis applied to a standalone block cipher. The method investigates, how differences of plaintext evolve while going through ...
Georgy Firsov's user avatar
1 vote
0 answers
44 views

Dealing with MITM attack in e-voting systems

I've read many e-voting papers that use El-Gamal scheme which I recall is vulnerable to man-in-the-middle attack, yet I find no discussion or even mentioning of it in those papers. -Does anyone knows ...
ShAr's user avatar
  • 160
1 vote
0 answers
80 views

Which cipher is used in this UDP stream? [closed]

I'm trying to analyze a stream of communication I captured from a game. I know the keys but I don't know how to apply them. I've tried: Various AES-256 modes, splitting the message at different ...
Krab's user avatar
  • 111
4 votes
0 answers
87 views

Cryptanalytic attacks ASCON MAC

I am researching ASCON. I can find cryptanalytic attacks ASCON authenticated encryption and ASCON HASH, But I am not finding anything ASCON MAC. Anyone knows of any attacks, any research on this?
Nicole Foster's user avatar
2 votes
0 answers
91 views

Source of encryption scheme used in blockchain based IoT

I've found the following encryption scheme UserA: $$sk_A, pk_A = sk_A \cdot G$$ UserB: $$sk_B, pk_B = sk_B \cdot G$$ Enc: UserA $$u \in \mathbb{Z}_q^* \\ Y = u \cdot pk_B \\ S = H(U) \oplus m \\ C = (...
coolgirl Leon's user avatar
1 vote
0 answers
46 views

Cryptanalysis of S-box [closed]

Because of implementation constrains, I merge some 4-bit S-boxes to find a 8-bit S-box with good properties such as nonlinearity, resistance against differential and linear cryptanalysis. Does the ...
Vahid's user avatar
  • 11
2 votes
1 answer
120 views

Does combining a stream cipher and block cipher produce any vulnerabilities?

In particular, AES-CBC with Blake2b for HMAC combined with xChacha20-Poly1305. The scheme is to encrypt with xChacha20-poly1305 first, using a key derived from a high entropy password using argon2id ...
bismofunyuns's user avatar
0 votes
1 answer
101 views

How to evaluate the minimum complexity of the key recovery when the success probability p is given?

Since the practical security of a symmetric-key primitive is determined by evaluating its resistance against an almost exhaustive list of known cryptanalytic techniques. My problem is that could we ...
HelloSpace's user avatar

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