Questions tagged [brute-force-attack]
A brute-force attack is attempting to find a secret value by trying all possible values until the correct one is found.
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NTRU Cryptosystem: Why "rotated" coefficients of key f work the same as f
In the NTRU cryptosystem, we can use a randomly generated polynomial f that is inversible under modulo p and q to encrypt and decrypt our plaintext. While studying this system, I attempted to ...
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Does higher key sizes correspond to a higher security parameter?
If a system provide n bits of security, it is known that the best possible attack against the system would be 2^n (security parameter).
However, why are the key sizes of some cryptosystems much larger ...
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Decrypting AES-128 with known regularly spaced single byte value [duplicate]
How would knowing a clear byte value of the decrypted data affect a brute force attack on an AES-128 encrypted message ?
i.e. If I knew the 1st byte should decrypt to 0xff
OR I knew that every 100 ...
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For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?
As stated for the question above here's an analogy:
You are a robber looking for a house to rob with two different scenarios that might occur.
1. You have a key that you know belongs to a house and ...
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How weak is using AES with a 128 bit key but 64 bits of the secret key are public constants?
Respected community,
I was wondering how weak would AES-128 be, if we provide only a 64 bit key with the other remaining 64 bits either zero bits or public constants, known to the attacker.
Is it easy ...
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On the exposition of SHA-1 attack (known_prefix + user_input + backend_secret)
In this question on sha1(known_prefix + user_input + backend_secret), an answer states that is realistically possible to find the first few bytes of ...
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Time Complexity of RSA Trial Division
I'm having trouble understanding how time complexity of trial division is exponential.
If it takes $\sqrt n$ tries to factor $n$ in the worst case scenario then time complexity is $\mathcal{O}(\sqrt n)...
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Can we find pairs $(c,m)$ with $f(c)=f(m)=true$ in $c = AES(m,K)$ with a fixed known Key $K$ significantly faster than brute force?
Different to the usual adversary use case we do not want to find the hidden key but instead pairs of $(m,c)$ which each fulfill a certain property $f(x)=true$
An example property could be e.g. 42 ...
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Publishing a message with a computationally enforced delay [duplicate]
I'm looking for a way to publish a message, so that it will only be publicly known after some time (let's say a few minutes). Even I shouldn't have the power to prove what my message was, before this ...
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RC4 Klein (or other) attack susceptibility question
What issues do yall see with the following in terms of key recovery and related key attacks:
RC4 used to "sign" a nonce:
3 byte nonce concatenated with 16 byte long term key > RC4 ...
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Identifying an encryption algorithm and/or writing an encryption function
I am currently trying to reverse engineer a piece of software that uses a seemingly-custom encryption algorithm.
After disassembling the decryption part of the code, I've come up with the following ...
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Is considered safe saving encrypting files using asymmetric encryption algorithm inside public environments?
I know restricting access of a file, is a important measure of security.
If we read the Payment Card Industry's Data Security Standard (aka PCI-DSS), we can see a requirement where control access must ...
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How can a preimage attack on SHA-256 always succeed within 2^256 evaluations when done though brute force?
I was reading the Wikipedia page for SHA-256 (SHA-2) and came across the following statement:
For a hash function for which $L$ is the number of bits in the message digest, finding a message that ...
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Is WPA2 collision-proof?
I was experimenting with hashcat and aircrack to test WiFi security.
The WiFi AP is a WPA2 encrypted network. The tool I used to ...
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Does file size significantly affect brute-force time?
Suppose you have two files encrypted with AES-256. One of the two files is 5MB, the other one is over 1GB. Their passwords are reasonably strong: >12 characters, letters, numbers, upper and lower ...
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Determining the initial positions of Engima's rotors
We want to perform a known plaintext attack on the enigma M3, the goal is to reach the initial settings of the 3 rotors. I tried to bruteforce those values since I know the plaintext, ciphertext, ...
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Clarification on expected number of plaintext, ciphertext pairs needed to identify AES keys
I'm aware of the many questions on this topic, but I'm still not sure what went wrong with my reasoning here below.
I'm assuming use of AES with key size $2^{256}$ and messages of size $2^{128}$, ...
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Is it possible to bruteforce a 200 bit hash generated with PBKDF2, in which the first 160 bit are known?
As some password manager, such as KeyPassXC allows a user to create a master password using a HMAC response from a YubiKey concatenated with a password entered by user, I was wondering something.
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Understanding the small cofactor attack with Elliptic Curves of non-prime order
I came across 2 older answers (2 different but similar questions on the small cofactor attack) which cover this attack.
https://crypto.stackexchange.com/a/12614/3941
Here the attacker replaces the $...
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Equivalance of encryption and decryption in DES under bruteforce
I am studying the vulnerability of DES algorithm.
Let there be a DES system with 5 keys, 56bits each. Encryption works as follows: (It's in this order on purpose)
$C=DEC_{k1}(ENC_{k2}(ENC_{k3}(DEC_{k4}...
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Quantifying the success probability of brute force attack against (search) LPN
I've been trying to learn about attacks on LPN ($n$-bit secret, noise rate $\eta$), and have found several allusions to a brute force algorithm that runs in time exponential in $n$ and requires a ...
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Does RIPEMD-320 provides the same level of security as RIPEMD-160?
This article from Wikipedia claims that "256- and 320-bit versions of RIPEMD provide the same level of security as RIPEMD-128 and RIPEMD-160, respectively".
Is that true or false ? And why ?
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Enumerating values from a linear congruential generator java Random()
During my research on a java application, I discovered that the nextInt(64) function of the java.Random() class is used to ...
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Are brute-force attacks made more difficult by removing the LUKS header?
If the LUKS header is removed from the LUKS partition, will this make the brute-force attack much more difficult? Can software tell which type of partition is it?
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64 bit key size Diffie Hellman
I am building a cryptographic El Gamal implementation on the Cardano Blockchain for a poker game. Each hand the players generate a DH 64 bit keys and shuffle the cards together via homomorphic ...
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Using MS Azure to crack password
I heard there is a possibility to perform a brute force attack of an password, I know there is an option to use graphic cards on AWS, but is there a solution for Azure too? Which costs would it take ...
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Protection (nonce addition?) against key discovery in AES 256
I've got a situation where I need to send message ciphered with AES-256. However the content, and therefore length, of the message may be intercepted before (don't ask;)) and the question I was asked ...
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How could I find the correct key pair given the plaintext and ciphertext
If I have a known plaintext and ciphertext pairs and 2 unknown keys of length 24 bits. (Assume encryption method is unknown)
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Is it possible to brute-force the nonce used in ECDSA?
It is a well-known fact that knowing the nonce used in signing the ECDSA signature allows the private key to be computed easily from that signature. If I understand it correctly, this nonce is a ...
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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 ...
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Statistical Cryptanalysis. Would one "reverse" weak key schedule algorithms or peel off each one of internal rounds?
The context is iterated ciphers.
Regarding Differential and Linear Cryptanalysis, the methods seem to make a cryptanalyst able to do an educated guess on a partial subkey (e.g. bits from the last ...
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How secure is it to share "Passwords" using Shamir Secret Sharing given a way to verify if password is correct?
Lets say you have a order $n$ finite field which you are using to create $k$ shares for a password using Shamir Secret Sharing. Assume that the attacker gets $k-1$ shares.
Is it possible that the ...
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Algorithms for reducing the scope of a brute force attack on a cryptosystem? [duplicate]
I understand that during a brute force attack on a cryptosystem, an attacker is left with many, many, junk files, some which are partially readable (depending on the crypto algorithm used), and 1 ...
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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 ...
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What are those RSA Challenges, DES Challenges and RSA Factoring Challenges
Can someone explain the differences between the DES challenge, the RSA challenges, and the RSA factoring challenge? What were the aims?
I think the factoring challenge was to encourage research, the ...
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Is it possible to get the SHA256 hash collision with partial known data
I have a text sentence that consists of 448 digits [0-9] [a-f] (in HEX format).
This text sentence is partially cut off, but I know the middle, and the beginning ...
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To what degree does a high PKBDF-HMAC-SHA1 iteration count compensate for a weak passphrase entropy?
Lost a LUKS-encrypted laptop at the end of 2019 and now trying to figure out the odds of a very sophisticated attacker being able to break in.
The LUKS container was created mid-2017 with LUKS1 ...
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Don't human generated passwords used with key derivation functions reduce the security of symmetric encryption?
The key size for AES is chosen as 256 because that's considered the minimum keysize which can protect against a brute force attack - i.e. $2^{256}$ tries.
However, in practice, for a lot of ...
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Does keeping the IV secret in OFB mode makes brute-force more complex?
If we keep the IV secret, does that increase the complexity of finding the correct key?
My first thought is that it increases complexity, but in real world, I can see that IV's aren't kept secret.
We ...
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Matching accounts across multiple data leaks via their hashed passwords
I've heard about several instances where OSINT researchers were able to match user accounts from multiple data leaks purely based on their hashed passwords, assuming accounts had the same password on ...
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Difficulty of computing RSA keypair with given bits preset
Given a 2048-bit RSA public key physically burned into hardware, is it feasible to find a keypair where the public key could be "overlaid"? To detail, each bit in the hardware key is write-...
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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 ...
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Proof of theoritical security of Shamir's secret sharing
community !
I'm looking for the proof of theoritical security of Shamir's secret sharing. I found some articles saying that it's assimilable to the halting problem, which implies that there is no ...
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Time complexity of a brute force attack on Shamir's Secret Sharing SSS
I have searched everywhere in academic papers about time complexity of a brute force attack on a Shamir's Secret Sharing key. I'm confused between if it is $O(p^k)$ or $O(p)$, such that $p$ is the ...
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How to calculate how long it will take to break deliberately weakened AES encryption?
for a project I'm looking to make as an art project a series of encrypted "time capsules" that have deliberately weak encryption, enough that it isn't feasible to crack them now, but could ...
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How to estimate time / difficulty to brute force scrypt (or similar) hash at various short fixed lengh outputs?
My particular use case is a hash function that:
Is slow / computationally expensive. It would take a pretty long time, or be infeasible to guess the input, if the hash output and the algorithm are ...
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how can identify which cryptanalysis is used ( Indistinguishability cryptanalysis against classical ciphers) [duplicate]
I have 10 ciphertexts and 10 plain texts I want to know which cipher is from which plain text
how can I know this
I know the name of substitution cipher, transposition cipher, Vigen`ere cipher and ...
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Number of plaintext–ciphertext pairs needed to rule out false keys with a reasonable likelihood in AES
I am new to cryptography and I've got the following question from Understanding Cryptography:
Imagine that aliens — rather than abducting earthlings and performing strange experiments on them — drop a ...
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How efficiently can an attacker forge parts of a fingerprint?
If two devices do not trust each other yet, you can't simply send the correct fingerprint across: you have to manually verify it. I am looking into the security of comparing only random parts of a ...
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How to express difficulty of breaking crypto when writing?
When writing for both technical and non-technical readers I find my self naturally wanting to write things such as :
"..therefore it would be impossible to decrypt the data."
When trying ...
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