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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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22 views

How to understand security analysis of encryption algorithm based on identity based and certificateless cryptosystem?

I am trying to understand the security analysis of cryptographic algorithms mainly identity based and certificateless public key encryption algorithm. I am finding it hard to understand the ...
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183 views

Poly1305 reuse of r

Poly1305 uses $r, r^2, r^3$ and $r^4$. I understand this if $r$ is a generator of the finite field. But since $r$ can be any random non-zero number, won't its exponents be non-uniform distributed? ...
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Understanding non-linearity in Salsa20 over various rings

In his design of Salsa20, Bernstein writes to ensure non-linearity he chose 32-bit addition (breaking linearity over $Z/2$), 32-bit xor (breaking linearity over $Z/2^32), and constant-distance 32-bit ...
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What are some statisitcal characteristics of a hill cipher?

Given a ciphertext, after performing a frequency analysis on it, how would you identify it as a hill cipher? What should i expect to see in the statistics?
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Introduce a reference for cryptanalysis of WhatsApp software

I am studying on cryptanalysis of WhatsApp software. I know this is secure software but I want to present a documentary on this topic as a seminar at the university for applied mathematics students. ...
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Algebraic differential cryptanalysis

I have been studying on algebraic methods on cryptanalysis of block ciphers. This is where I am reading from currently I need some help to understand Attack C. Excluding equations from the first r ...
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Key recovery step of Related key Cryptanalysis of Full AES-256

I am reading the article Related-key Cryptanalysis of the Full AES-192 and AES-256 but I cannot understand the key recovery part in chapter 5. The author divides the key rocovery into 5 parts and ...
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Chaos-based AES, is it secure?

I am not a fan of Chaos-based cryptography, however, I am analyzing it to show its drawbacks. The chaos-based ciphers are often weak, to the best of my knowledge. In the link below, the author uses ...
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109 views

What is the easiest encryption/cipher to brute force?

This is just a casual exploration of what could be effectively the worst possible block cipher, but I think it has some educational value on how ciphers work. I've been reading about unicity distance ...
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Differential analysis of SPN

Reference : Tutorial by HM Heys If we find a differential trail that holds with some non negligible probability for n-1 rounds for a n rounds SPN structure, then we can recover some of the bits of the ...
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107 views

Crypt-analysis for finding information hidden in images?

I was wondering if anyone is familiar with any historical aspects (as to whether someone was able to) for discovering code using images on the web as a transport method ? As in hiding byte values in ...
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60 views

A query regarding SHA256 output hash structure vs input entropy?

Given an Input string of N bytes where some bytes positions in the string are fixed/immutable (F Bytes) and rest of the bytes positions can contain any value as we want or are configurable/variable (V ...
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(Non)security of algebraically derived EC keys

I recently had a situation where I needed to derive a secondary Curve25519 private key from an existing one programmatically. The obvious solution was to use a KDF, but I wondered at the time about ...
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Vigenère cipher with switching keys

I am looking for possible ways of attacking a modified Vigenère cipher. Let's say we have two keys e.g. 'stackoverflow' and 'Vigenère'. The V cipher starts with one of those keys but switches as ...
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37 views

Is it allowable to put a restriction on the length of the plaintext used in the known-plaintext attack?

The definition of the known-plaintext attack: I have a plaintext and I can encrypt it to have its ciphertext, then I use this pair to break the cipher. The question: The only thing I further assume is ...
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How can I do cryptanalysis on a chaos-based cipher?

I have been reading about chaos-based cryptosystems. Every designer claims that his design is a secure system without much cryptographic analysis; however, it turns out that this is a false claim in ...
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123 views

Decryption of an unknown cipher

How can I identify the cipher that encrypted the data shown below? I'm very new to this field, so I am not sure. For example: How does one know which cipher is used in the following line? How can one ...
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Which contemporary programming language is apt for implementation of algorithms in cryptography?

I am a researcher in cryptography. Most of the time I generally do theoretical/Mathematical work only and not doing the implementation part. I am not able to get the feel about the time complexity of ...
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ε-close to t-wise inependence of SPN (AES)

According to theorem 3.13, the 6 rounds of AES is 0.472-close to pairwise independence. It is also mentioned t-wise independence used to analyze higher order derivates attacks. it is also mentioned 3-...
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What vulnerabilities does the LFSR filter generator have?

As the title suggests, I wonder what kinds of attacks there are in the LFSR filter generator. The most representative attack is the fast correlation attack and inversion attack. I wonder what other ...
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129 views

Does SHA-256 have (128-time + 128-space = 256-overall)-bit collision resistance?

First, we consider those hash functions that can actually provide 256-bit pre-image security, and not something like SHAKE128<l=256bits> where the sponge ...
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197 views

Does this paper find cryptographic weakness of SHA-256?

I found only the abstract and tables of this paper https://dl.acm.org/doi/abs/10.1145/3409501.3409513 From the abstract In this paper, the researchers proved that the modified SHA256 is viable to ...
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CrypTool RSA Features [duplicate]

I am attempting to manually encrypt a plaintext message (message = MI) using RSA. I receive an answer of: 33,264 and 21,164. When I enter the same plaintext into CrypTool to confirm that my ...
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A few questions regarding the 4-Round AES-Distinguisher (by Gilbert and Minier) and DS-MITM

I am struggling to understand the DS-MITM attack on AES (Original Paper). Especially the 4-rounds distinguisher by Gilbert and Minier (section 3). I get the basic idea that we check exactly on which ...
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Decrypt encryptedKey session key using - AES-128 - PKCS-1#rsaes-kem-kdf2-kw-aes128

I have basic knowledge about how encryption algorithms work such as RSA, AES and so on. I have an XML response encrypted with both AES and RSA. I tried using OpenSSL to decrypt with several steps but ...
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91 views

Why is this DES key considered weak?

I understand the premise of weak keys in DES and cryptography. From searching online, I understand that keys that are comprised of all zeroes / all ones / alternating ones and zeroes / alternating ...
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Differential cryptanalysis to ciphertext-only attacks on xxTEA

In my IOT project, I use the xxTEA encryption algorithm to encrypt my data. I use the same encryption key for all my packets because I don't have the possibility to do a key exchange between Alice and ...
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Need some help with decryption code for monoalphabetic substitution

I am working on decrypting ciphertext in monoalphabetic substitution algorithm. I tried to decrypt using frequency histogram of English alphabets individually. The percentage of these frequencies can ...
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64 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 ...
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1answer
78 views

Complexity of Boomerang Attack on COCONUT98

I am trying to understand the paper The Boomerang Attack from David Wagner. On page 162 about complexity of boomerang attack the paper says that: The attack requires $8 \cdot 2 \cdot 32 \cdot 2^{32} ...
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How does a forward search attack work? [duplicate]

I just came across this term “forward search attack” while reading about Interchange key and Session key. The book mentioned that using session key helps to prevent attacks such as forward search ...
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1answer
65 views

Is a Test Vector feature a Security Hole?

I have a system where a block cipher key (likely AES) is entered via a 'command line' over a serial console, probably as hex. The system has no 'print key' feature, so the key is hopefully 'ingest ...
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Nonlinearity of a Boolean function with odd number of input bits

Highly nonlinear functions are used in combination generators and other stream ciphers. We know that maximum nonlinearity (hamming distance to all affine functions) of $f$ is achieved when $f$ is bent ...
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119 views

Verify that a point belongs to secp256r1

I need to verify that the point in this public key ...
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71 views

How to determine secp256r1 or secp256k1 is used on the web sites

I'm pretty new at Cryptography (and at Cryptanalysis), but I went to the website Elliptic to try to discover the elliptic curve they use, and I found they use ECDP 256. So, by SEC2 I discovered they ...
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35 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 ...
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Does the diffie helman rachet in double ratchet do anything if one side never replies?

I am a little confused on how this functions so apologies in advance if the question is naive. The way i understand it, the function of the standard sending and receiving ratchets in Double Ratchet is ...
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Few questions about setting up SuperCop primitives

Have a couple of questions about the supercop library. I've refrained from asking this question for a considerable amount of time because every time I thought about asking it, it sounded stupid in my ...
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61 views

Cryptographic Principles: Bit-Flipping Attack

I'm working and reading about bit-flipping attack and how to set it up. I just got a question, which I am not sure, how I should answer. Question: 'Why is this easy with a stream cipher but not ...
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Comparison of SNARK-friendly hash algorithms MiMC7, Poseidon, Pederson?

There are some cryptographically secure hash algorithms designed to be efficient for SNARKs, STARKs and FHE. Some of them already implemented in Zcash, Zokrates and circom. The ones that I know of are:...
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38 views

Paillier estimate attack costs on short keys

I was thinking about how to use the homeomorphic property of that cryptosystem to achieve not a "semantic security" but a less ambitous obfuscation of the source code (an ipotetical scenario ...
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Difficult to guess the targeted receiver

The protocol is defined as : Bob want to send message to one of his friends say $k$ friends , he does not want his others friends (except one whom he want to send message ) to tell who is targeted ...
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44 views

How to find Difference distribution table of DES S box?

I Have used Sage command ...
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I was going through Path ORAM in oblivious RAM. I found it very interesting, as its promising but is there any scope left to enhance it?

Is there any specific field in Path ORAM where I can further investigate or research?
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How do I model this system?

I was trying to work out the security of an system that used the polarized LCD panel over an OLED display (the point being that you can only block certain pixels) and the pixels are either on or off (...
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279 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 ...
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89 views

Using $key^{th}$ multiple of $\pi$ as a one-time pad

With a key $k$ of sufficient length, say 128 bits, is it possible to use $k^{th}$ multiple of $\pi$ as a one-time pad? Please enlighten on the security as well as practical aspects (only if secure of ...
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64 views

What are "unspecified" differentials in a differential characteristic?

I've been studying many papers on differential cryptanalysis and I see that in the published differential characteristics, such as in the appendices of [1], [2] and [3], some differences are left &...
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78 views

How exactly to concatenate two differential trails to form a boomerang disguisher in practice?

I've been reading many papers on boomerang/rectangle attacks. The general strategy is to find two trails for a small number of rounds and then concatenate them to form a longer distinguisher. ...
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192 views

Can Big Data together with deep neural networks attack RSA by affording the vast calculation of prime multiplications in advance?

This is a spin-off from Can Big Data attack RSA by just calculating many prime multiplications in advance? [duplicate]. Intro I am somewhat new to cryptography. Repeating the basics of RSA from How ...

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