# 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”).

1,553 questions
Filter by
Sorted by
Tagged with
1 vote
1 answer
10 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 ...
1 vote
1 answer
45 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 ...
2 votes
1 answer
148 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 ...
• 123
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 ...
• 22.1k
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 ...
• 33
0 votes
1 answer
61 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 ...
2 votes
1 answer
90 views

### Not understanding elliptic curve scalar multiplication to produce Ethereum address

This is the equation Public key = Private key * G Here, ...
• 123
-1 votes
1 answer
67 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 ...
• 1
1 vote
2 answers
307 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 ...
0 votes
0 answers
45 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*} ...
1 vote
1 answer
105 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?
• 11
0 votes
0 answers
144 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 ...
3 votes
1 answer
111 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 ...
0 votes
0 answers
53 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 ...
• 1
0 votes
0 answers
63 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 ...
1 vote
0 answers
36 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 ...
• 152
1 vote
0 answers
76 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 ...
• 111
3 votes
0 answers
74 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?
2 votes
0 answers
91 views

• 11
0 votes
0 answers
33 views

### Security Analysis: Adversary's Ability to Recover Concatenated and Hashed Secret with Partial String Knowledge

Suppose I have the following secret, calculated by concatenating and hashing the results of two random strings: secret = H( H( random_string1 ) || H( random_string2 ) ) Let's assume that the adversary ...
0 votes
0 answers
35 views

### How by changing ciphertext can the attacker know the length of the padding in POODLE attack

I try to understand the POODLE attack. I read that the attacker try to change one byte of the last block of the ciphertext. Becasue the last block is only have padding and the last byte is the padding ...
• 31
1 vote
1 answer
73 views

### DDT for boolean functions must contain only powers of two

I see in many discussion on differential cryptanalysis of SBOX (and others boolean functions, see SIMON-like round functions, SPECK-like round function) the idea of reasoning in terms of weights ...
5 votes
1 answer
132 views

### Cryptanalysis of the GOC

The GOC (Générateur d'Octets Chiffrants, Ciphering Byte Generator) is a PseudoRandom Generator that was used during the late 20th century for content encryption in pre-internet Videotex terminals, ...
• 140k
2 votes
1 answer
59 views

### How to convert a Modular addition to conjunctive normal form (CNF)? [closed]

If I have three integers $x,y,z\in \mathbb{F}_{2^n}$, How do I convert the modulo addition operation into conjunctive normal form (CNF)? $$(x+y)\pmod{2^n-1}=z$$
0 votes
2 answers
81 views

### May specifying the position of swapfile help defeat LUKS encryption?

I need to enable hybernation to the LUKS-encrypted drive. My /boot partition is unencrypted hence it stores all kernel images as well as kernel parameters in unencrypted form. For hybernation to work ...
3 votes
3 answers
308 views

### How big of a threat are *diffusion model* based AIs to cryptographic systems?

The diffusion model, which is used by products like Midjourney and Dall-E, trains AI systems to de-noise (remove added randomness) from data to infer what the original de-noised data is. That would ...
• 785
0 votes
1 answer
80 views

### Finding out corrupted S Box value in DES implementation?

I am using DES encryption when writing a file in an embedded device. When I decrypt the file. I get a partially corrupted file. Kind of randomly some 8-byte blocks are corrupted. Some are not. When I ...
0 votes
1 answer
72 views

### Safe implicit value validation: $H_k(k \oplus m) \sim H_k(m)$?

$H_k$ is a cryptographic hash function that's keyed using a section of key material $k$ (for whatever definition of "keyed" that's appropriate for the given hash function $H$). Are the ...
• 785
0 votes
0 answers
19 views

### Finding key using Mutual Index of coincidence / Mg from vigenere ciphertext [duplicate]

I'm new to cryptography and I was trying to find key to an intercepted vigenere ciphertext using ciphertext-only attack, I'm following book "cryptography and network security" by Forouzan. ...
0 votes
1 answer
48 views

### Is there a way to short circuit (speed up) hashing a large but sparse array?

Imagine a large array (Megabytes) that is virtually empty, i.e. contains 0 in almost all locations. But also imagine there's 1000 pseudo random locations that contain a pseudo random byte. There is ...
• 15.3k
2 votes
1 answer
189 views

### Can I predict CryptGenRandom on my own device?

I have a Windows 10 laptop with an algorithm that creates a random number using the PRNG CryptGenRandom. According to Wikipedia: Because CryptGenRandom is the de facto standard CSPRNG in Win32 ...
• 221
2 votes
1 answer
94 views

### Is hash function cryptanalysis the same or more difficult for iterated hashing, as H(H(H(H(H))))?

The effectiveness of hash function attacks is typically measured in $x$ broken rounds of $N$ total designed rounds. And some constructs containing iterated hash functions include proof of work schemes,...
• 15.3k
1 vote
2 answers
83 views

### Given $i$ keyed-$PRP$ labels $\ell_{i,x}$ from a $2^{256} \times 2^{256}$ Sudoku (Latin-square), how difficult is it for an adversary to solve?

There's a keyed-permutation I'm playing with, $\ell_{i,x} = \pi_i(x_i)$, which is a bijection $X \leftrightarrow X$, where $|X| = 2^{256}$, and whose evaluations on plaintext inputs $x_i$ perfectly ...
• 785
0 votes
0 answers
45 views

### Is combining Elgamal algorithm and RSA algorithm for key generation and AES+RSA algorithm for encryption and decryption a novel approach?

Key generation: Key Generation Firstly, the RSA algorithm will be used to generate a public and a private key. Generate two random prime numbers p, q. Select RSA public key, P k such that gcd(P k, Φ)=...
1 vote
0 answers
79 views

### Literature on (concrete) hardness of Short Integer Solution (SIS)

I am interested in what the state of the art results on the hardness of the Short Integer Solution (SIS) instances are. The one I am the most familiar with (and the most discussed) is to use lattice ...
• 350
0 votes
1 answer
149 views

### Trouble detecting cyclic group order crossovers in SECP256K1

There's a problem in detecting whether the sum of public key addition has crossed the cyclic group order boundary For this example, think of public keys $Pub$ as private keys $Priv$, (private scalars),...
1 vote
4 answers
183 views

### Good references to breakable limits: $2^{60}$

Recently, I read here on Crypto SE that $2^{60}$ doesn't provide enough resistance to current adversaries. Could someone please provide me with good references related to that threshold, or any ...
1 vote
0 answers
58 views

### Misuse Attacks on Lattice Crypto

I've been reading "Misuse Attacks on Post-Quantum Cryptosystems" (https://eprint.iacr.org/2019/525). In what scenarios are the attacks described in the paper applicable? Is it specifically ...
• 423