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”).
1,492
questions
2
votes
2
answers
67
views
Best Known Attacks on Discrete Logarithm in Generic Groups
This is a followup to my recent question Discrete Logarithm Challenges and Records.
I am interested in confirming my understandings from the answer to that question, stated below:
For a discrete ...
- 19.9k
1
vote
0
answers
38
views
Bit based division property
Bit based division property is a great method of Integral attack on block ciphers, which was invented by Y. Todo.
According to the paper Bit-Based Division Property and Application to Simon Family (in ...
- 141
1
vote
1
answer
53
views
Is it fatal if a blockcipher uses a sbox with a fixed point at 0?
In a previous question, I asked how to implement arbitrary s-box in side-channel-free fashion. The code I posted in the question loops over all 256 values of a byte to avoid timing channel, and I want ...
- 8,263
-6
votes
1
answer
69
views
Are Schnorr's algorithm really subject to q-computer attacks?
I was wondering whether quantum-computers really break Schnorr's signature scheme. Schor's algorithm works via the quantum Fourier transform, which reveals the cycle time and thus phi. However, with a ...
0
votes
0
answers
42
views
New POST heaviest-chain finder without downloading any blocks or trusting a checkpoint?
In a POST consensus mechanism with no starting stake needed, I may have found a way to sync with the correct chain without a.) trusting checkpoinnts or b.) downloading the whole chain (or even part of ...
0
votes
0
answers
44
views
Why using linear increasing nonce in DSA in a bad idea?
Suppose we sign and verify messages with a DSA scheme. Before signing the first
message the necessary parameters $(p,q,h,g,x,y)$ are initialized, including the nonce $k$ as an integer between $(1,q-1)$...
- 1
1
vote
2
answers
64
views
decrypting full ciphertext of (AES CTR/GCM) based on partial knowledge of the cleartext
I have found myself in a position where I need to encrypt multiple objects (vCards) with AES Counter mode or Galois/Counter Mode using the same key. Now here is the problem the structure of the vCard ...
- 153
1
vote
1
answer
45
views
DH Finding A Public Key from Public key and shared secret
Is there a known feasible method for determining an unknown public key from a Diffie Helman shared secret and the other public/private key pair?
This would be rarely useful, but I am curious if the DH ...
- 33
1
vote
0
answers
42
views
Tensor and power bases for SIS?
What is there to say about using a power basis or a tensor basis or some combination of them for the RSIS problem in lattice cryptography?
Restricting to dimension 3 for illustration, usually the ...
- 357
1
vote
0
answers
25
views
Secure ciphersuite from security-wise sub-optimal unkeyed permutation?
Hypothetically,
IF we were to create a SSL/TLS or QUIC ciphersuite from a single (unkeyed) permutation operating in sponge mode to provide hashing and duplex mode to provide AEAD cipher,
AND IF the ...
- 8,263
2
votes
0
answers
25
views
Exploit 3DES-CBC with known checksum of plaintext and repeated IV
I came across the following enterprise encryption scheme. I laughed when I first saw it, but I'm not a specialist and I'd like to know how bad it really is.
3DES-CBC
k1=k2=k3 for 3DES
IV for CBC is ...
- 121
3
votes
0
answers
104
views
Are there "light" versions of cryptographic hash functions?
After tinkering with cryptographic hash functions, I started wondering if they do have counterpart functions that would imitate their cryptographic properties but with a lower level of strength in ...
- 153
2
votes
1
answer
105
views
Attack on the chosen plain-text RSA
Reading another user's question, a doubt came to me.
Suppose an RSA oracle exists, with which it is possible to interact to encrypt and decrypt some text. The oracle output is not the decrypted text ...
- 33
1
vote
0
answers
23
views
How can I perform a one-client MITM attack in a Diffie-Hellman key exchange? [closed]
Suppose we have intercepted a public key exchange (via Diffie-Hellman protocol). In addition to the keys A and B, the generator g and the module p are known.
Assuming that it is possible to exchange ...
- 11
2
votes
0
answers
17
views
Product Cipher with Two Autokey Cipher
I have a cypher text with I know encrypted two times with Autokey Cipher with same lengths of keys. I am following the statistical cryptanalysis in here when it is ciphered with one time with Autokey ...
- 21
3
votes
0
answers
88
views
Cryptanalysis of ARX Ciphers
Rotational Cryptanalysis of ARX show that rotational probability of an ARX primitive can be computed by $p^q$ where $p$ is rotational probability of modular addition and $q$ is number of modular ...
- 2,377
1
vote
0
answers
71
views
Which encryption method support 256 bytes block size?
I am looking at some secret encryption method that apparently uses CBC and a block size of 256 bytes. I can do a chosen-ciphertext-attack. When I modify a single byte in the ciphertext a complete ...
- 11
1
vote
2
answers
73
views
Rule 30 based block cipher
So I went ahead an wrote this little program. What it does is it takes a password for a seed and generates a (pseudo-random) bit-pattern using rule 30 from cellular automata. It then XORs our input ...
- 111
1
vote
2
answers
459
views
Stuck on a cryptanalytical research project [closed]
This is not a technical question, but rather it seeks advice on what to do if cryptanalytical research goes wrong.
I've discovered a new attack that works great in theory, but in practice, it fails.
I ...
- 11
0
votes
0
answers
229
views
RSA : Is there a way to compute phi(n) or N itself if we only know e, d and a ciphertext?
I am trying to solve a problem where private key exponent d, ciphertext c, and public key exponent e (65537) are known.
How can I calculate φ(n) or n itself?
An extended version of the problem would ...
- 13
2
votes
1
answer
105
views
Confusion+Diffusion comparison table? (e.g. with Avalanche Criterion / SAC)
I'm looking for a general comparison of encryption algorithms in regard to Confusion and Diffusion (as defined by Claude Shannon),
and if possible, specifically for their SAC and BIC quality.
For ...
- 145
4
votes
0
answers
53
views
Where did the number of initial plaintexts required for impossible cryptanalysis on Mini-AES came from?
I'm implementing impossible differential cryptanalysis on AES and I've started with implementing it on mini-AES to fully understand the process using R.Phan's paper as a reference.
But I don't ...
- 191
0
votes
1
answer
56
views
Differential trails in differential cryptanalysis
From section 4.4 of this book https://www.ic.unicamp.br/~rdahab/cursos/mo421-mc889/Welcome_files/Stinson-Paterson_CryptographyTheoryAndPractice-CRC%20Press%20%282019%29.pdf
I'm confused on how the ...
2
votes
0
answers
25
views
how to build the plaintext structure for impossible differential cryptanaysis on IDEA?
I'm trying to implement impossible differential cryptanalysis on 3.5 round IDEA using Miss in the Middle Attack on IDEA and Khufu paper as a reference and I'm stuck on the first two steps of the ...
- 191
1
vote
1
answer
119
views
Calculate the key of a Hill-cipher using known plain- and ciphertext
I know I should calculate the multiple inverse of plaintext with ciphertext $\pmod {26}$. However, the problem I have is that the plaintext is a $3 \times 4$ matrix which is not square, so how would I ...
- 11
1
vote
1
answer
75
views
Size of nonlinear filter sequence to recover LFSR feedback polynomial
Let's suppose that there is a filter generator which based on $n$-size LFSR.
Denote a feedback polynomial as $g(x_1, x_2, \dots, x_n)$ and nonlinear filter function as $f(x_1, x_2, \dots, x_n)$.
Let $...
- 11
0
votes
1
answer
103
views
How does AES-CBC encryption achieve non-repeating blocks of ciphertext?
I am very interested in encryption algorithms, especially AES encryption algorithm in symmetric encryption. To this end, I have studied a lot of theoretical knowledge about AES encryption algorithm ...
- 21
2
votes
1
answer
63
views
Conceal time-based GUIDs with an affine-cipher?
I'd like to create a custom type of sortable GUID by concatenating an 8-byte nanosecond timestamp, 6 random bytes, a 1-byte node number, and a 1-byte counter. But, such a precise timestamp can be used ...
- 53
1
vote
1
answer
197
views
Chosen-plaintext attact on AES with MixColumns omitted
Jean-Philippe Aumasson' "Serious Cryptography" says: "Without MixColumns, changes in a byte would not affect any other
bytes of the state. A chosen-plaintext attacker could then decrypt ...
- 11
5
votes
2
answers
190
views
In a PGP like Application , would compress and encrypt leak information
would compress and encrypt on data comromise security for PGP like application, would it be secure for use in Encrypted Messaging?
I have heard its safe for data at rest encryption , i have heard ...
4
votes
1
answer
154
views
A modern rotor machine, could it be any safe?
I wonder if a rotor machine similar to enigma can be considered secure by today's standards under four conditions:
A rotor machine which consists of 50 rotors picked out of a set of 100.
A rotor ...
2
votes
1
answer
76
views
Significance of theoretical weaknesses?
What is the significance of theoretical weaknesses?
Any real life incident where a theoretical weakness was ignored and later it compromised the system? Whats the dividing line between theoretical and ...
- 2,377
1
vote
1
answer
131
views
What are the best known cryptanalytic attacks against AES-128 with 9 rounds?
What are the best known cryptanalytic attacks against AES-128 with 9 rounds?
I found many such attacks on AES-192 and AES-256 with 9 rounds, but not for AES-128 with 9 rounds.
Are there any ...
- 47
1
vote
0
answers
48
views
By using a block cipher multiple times in a row is a 128-bit BC as secure as a 256-bit BC which uses his 128-key only as part of the message?
For given 128-bit numbers $S$ and $E$ we want to find a series of keys $k_i$ with
$$ E = BC(BC(BC(.....BC(S, k_1),k_2) ..k_n)$$
We can either use a 128-Bit blocksize block cipher similar to AES (ECB ...
- 557
1
vote
1
answer
69
views
How does the security of AES change if we allow multiple uses in a row? How does it change if we limit the key space? And introduce a filter function?
$$f_0 = A$$
$$f_{n+1}=AES(f_n,k_n)$$
$$f_i = B$$
For given 128-bit values $A, B$ we want to find a chain of suitable 128-bit keys $k_1$ to $k_i$.
The total length $i$ is undetermined. Every valid key ...
- 557
3
votes
1
answer
145
views
Why is the best way to solve LWE (and Cryptographic related Systems) with SVP (approx)?
Community,
I'm new into lattice based cryptography, and I'm interested about the security of cryptography schemata like Kyber and why the focus of solving this problem lead into solving approx. SVP.
...
- 65
1
vote
1
answer
231
views
Best attack estimates on AES
The wikipedia article on the Advanced Encryption Standard claims an attack against AES-128 with complexity $2^{126.1}$. The NIST call for proposals for post-quantum cryptography (table on page 18) ...
- 835
0
votes
0
answers
57
views
Security proof of the Schnorr Signature
How Schnorr signature security can be proved for signature forgery, replacement, and Replay attacks?
- 1
1
vote
0
answers
63
views
Non-uniform plaintext distribution -- AES attack
Are their any attacks on AES (any mode) in which before the attack is mounted, the adversary is aware that the input distribution is non-uniform?
Most of the work assume that the plaintext is ...
- 31
2
votes
0
answers
98
views
Automated Security Protocol tool that models algebraic operations
Are there any automated security protocol verification tools that model algebraic operations; specifically addition.
I am familiar with AVISPA and Verifpal, and they are both great and user-friendly ...
- 157
1
vote
2
answers
59
views
How fast does revealing parity bits leak information?
I've got a scheme where I XOR a secret key value with a public (but random) value, XOR together all the bits of the result, and publish that bit (0 or 1), which is the parity of the result of the XOR. ...
- 111
6
votes
0
answers
453
views
How the mimc bug from circomlib was safely exploited in practice?
Several years ago, there was an unenforced constraint on verification in the cirmcomlib library : a tool for building projects using ZsNarks. The error allowed to forge cryptographic nullifiers/proofs ...
- 185
2
votes
1
answer
119
views
How bad exactly are repetitions in the plaintext?
When the last n bytes of the plaintext are themselves suitably random, but predictably repeat m times in the same message - how bad is that? I'm convinced it is detrimental, but I am uncertain how ...
- 145
1
vote
0
answers
61
views
RSA decryption problem knowing public key and ciphertext [closed]
new member here.
I am taking a course in computer security, and we just got introduced in Cryptography and especially in RSA Algorithm. Although i got the 'basic idea' behind the RSA algorithm and the ...
2
votes
1
answer
165
views
Info AES cryptanalysis
I have some doubts regarding AES weakness and AES cryptanalysis. While it is relatively simple to find Cryptanalysis info on previous ciphers, I get confused about understanding various types of ...
- 71
1
vote
1
answer
22
views
Statistical closeness of distributions and time-unbounded distinguisher
If two ensembles are statistically indistinguishable, we all know that they are also computationally indistinguishable, i.e., for any PPT algorithm, the probability to distinguish them is negligible.
...
- 143
0
votes
2
answers
77
views
What is the standard checklist for designing a Key Derivation Function?
What kinds of properties does a KDF need to have in order to be considered secure? What steps should be taken during analysis to test for flaws?
In particular, I mean a KDF that is going to be used as ...
- 33
2
votes
1
answer
193
views
How to solve this Baby Bleichenbacher Attack?
I am trying to solve this problem from https://toc.cryptobook.us/book.pdf.
I am having trouble with this question :
(Baby Bleichenbacher attack). Consider an RSA public key (n, e), where n is an RSA
...
- 21
0
votes
1
answer
89
views
How do I know the most efficient image encryption algorithm?
I am familiar with any algorithm that is based on the number of bits in a key (n-bit) and how to restore a key, such as the Discrete Logarithm Problem or Factorization.
When I use any algorithm for ...
- 431
2
votes
1
answer
544
views
A probable attack for RSA (factorization): how to improve it?
A probable attack for RSA (factorization): how to improve it?
$N=8*G+3$ can be factored if there is a non-trivial negative $k$ such that
$\frac{(N*(9+24*k)-3)}{8}=-6*m^2 $
[to exclude the two trivial ...
