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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How much computing resource is required to brute-force RSA?

It's been over 30 years since Rivest, Shamir and Adleman first publicly described their algorithm for public-key cryptography; and the intelligence community is thought to have known about it for ...
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83 views

What is the danger if a non-prime is chosen for RSA? [duplicate]

I was reading this question about generating primes for RSA keys. The answers point out that most implementations of of the algorithm use probabilistic prime-ness checking algorithms. The answer by ...
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74 views

Brute-force attack given multiple hash prefixes

(Context: I'm auditing some code which I suspect to be insecure, but I'd like to be able to quantify this.) Suppose you have a 56-bit secret key ($secret), and ...
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87 views

Unbreakable code and mathematical impossibility

Is an unbreakable code mathematically possible , considering a code with finite number of characters but has infinite combinations , using brute force is it not compulsory that the correct code be ...
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66 views

Brute Force on Key

If you are brute forcing a key and trying trillions of combos, how will you know when you accidentally hit the right answer? Clearly you can't look at each decoded answer to see which "looks right".
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1answer
72 views

Has a collision ever been found for SHA-1/2/3 when truncated to 128 bits?

I'm aware that MD5 is broken, and collisions have been found for it. I'm interested in other hashes (SHA-1, SHA-2, SHA-3) when truncated to the same digest size, i.e. 128 bits. The time complexity of ...
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198 views

Elliptic curve brute forcing

I have elliptic curve of equation $y^2 \equiv x^3 -x $. And the coordinate of points $Q$ and $P$. I want to solve $Q=[k]P$ (where $k$ is the unknown) by testing all possible $k$. Is this the right ...
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3answers
648 views

What is the difference between online and offline brute force attacks?

I read some papers saying a certain scheme is secure for offline brute force attacks, but vulnerable to online brute force attacks. I wonder the difference between the online and offline brute force ...
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8answers
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How much would it cost in U.S. dollars to brute force a 256 bit key in a year?

I am often told that any key can be broken and that it is only a matter of time and resources for any key to be broken. I know that this it technically true. However, I think that there is probably a ...
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How Brittle Are LCG-Cracking Techniques?

There are published techniques for cracking LCGs, but to my eye those techniques seem very brittle — very minor changes can add nonlinearity that renders techniques like the LLL algorithm unusable. ...
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1answer
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Practical brute-force attack on 128 bit encryption

In brute-force attack calculations cryptographers say we should assume an attacker will find the key after $2^{(n/2)}$ tries. If n=128, then n/2=64. We know that this is practical (A 64 bit key is ...
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316 views

Practical Attack on RSA

Currently I am designing an RSA based application, and I am thinking of how long should the key be in order to be secure against attacks. I know that RSA 4096 bit key can be recovered using Sound ...
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38 views

Resynchronizing brute-force attack against stream ciphers

There is a stream cipher without any known cryptographic weaknesses. The attacker knows parts of the key so she can reduce the key-space to a size that can be practically brute-forced. However the ...
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1answer
124 views

Java RSA Padding: no libraries used

I'm trying to implement RSA without using any java libraries using the algorithm from wikipedia HERE So, anyone can clearly see that it is a raw RSA, and can directly be attacked. The question is ...
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3answers
208 views

When is a cipher considered broken?

We've all read how some people claim AES is broken because there was supposedly a way to get the plain text from a cipher text faster than brute-force. But is this the definition? Is a cipher broken ...
6
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1answer
171 views

what is the current actual budget - as of 2015 - needed to build a DES breaker machine?

EFF - Electronic Frontier Foundation - built a DES cracker for a budget of 250K$ in July 1998. I assume that as of 2015 - the cost of such a DES breaker would be less, are there any estimations about ...
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1answer
277 views

Why is AES unbreakable?

Why is it said that AES is unbreakable? Brute force attacks would take years to crack it, so is it possible to crack it if the computational speed of machines increase in the following decade?
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3answers
846 views

Kryptos : K1. What is the origin of the “palimpsest” keyword?

I'm studying the Kryptos sculpture with its cryptographic puzzles K1 to K4. I understand that the keyword "palimpsest" was reverse-engineered using the tableau (and brute-force computer processing), ...
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3answers
801 views

Kryptos : K2. What is the origin of the “abscissa” keyword?

I'm studying the Kryptos sculpture with its cryptographic puzzles K1 to K4. Similar to the "palimsest" keyword for K1, the keyword "abscissa" for K2 was determined by brute-force. To better ...
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3answers
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In what way is XXTEA really vulnerable?

I'm looking at using the XXTEA algorithm to encrypt a small amount of data (say, less than 32KB) in the context of a software licensing algorithm. That is, we wish to make it difficult (not ...
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4answers
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Do Brute-Force Attacks and Cryptanalysis refute Kerckhoffs's principle? [closed]

According to Kerckhoffs's principle "A cryptosystem should be secure even if everything about the system, except the key, is public knowledge." Now I want to throw in a provoking formula of mine which ...
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0answers
40 views

DES key complementation property [duplicate]

It is known that DES has the key-complementation property. That is, given any key $k$ and any message $m\in\{0,1\}^{64}$ $$\operatorname{DES}_k(m)=\overline{\operatorname{DES}_\overline k(\overline ...
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1answer
304 views

BruteForcer XOR (bfxor.exe) to attack 64-bit keys and longer

First of all, this is not a beginner's question since I already know a good deal about encryption and brute-force attacks. This is also no question on how to code programs for brute-force attacks ...
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179 views

Brute Force AES Calculations

I have an encryption service in which the user decides the length and the type of key, so I would like to build a tool that educates the user on the brute force times for the key they created if using ...
2
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1answer
220 views

Small Encryption Exponent

I am trying to crack an unpadded RSA set up for a homework. I have public key (R,e) and encrypted message E. ...
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141 views

Does brute force attack use the program that created the ciphertext?

I've read several articles about brute force cryptanalytic attacks, but none explicitly say what algorithm is being run for each attempt, nor what criteria is used to declare an attempt a success or a ...
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Brute Force Attack Strategies

A Brute Force Attack obviously involves attempting to decrypt ciphertext (with the associated plaintext being known) using all possible encryption keys. Aside from attempting all possible ...
2
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1answer
256 views

AES-128 with weak key

Doing malware research (simple crypto locker) I found out that it uses AES-128 with weak key - every one of the sixteen bytes is represented by (a-z,A-Z,0-9). Thus simple brute-force attack should ...
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1answer
172 views

Hashing passwords

The common way to store passwords in web applications is this form: $$hash(password||salt)$$ Does it make sense to store them in the following form instead:? ...
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2answers
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Can I crack an AES string if I have all these parameters?

This is for a challenge at followthewhiterabbit.trustpilot.com: Knowns: The algorithm is AES (Rijndael) Blocksize: 128 Keysize: 256 You only need to find the first 6 bytes of the ...
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3answers
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Is there some way to generate a non-predictable random number in a decentralised network?

Is there a way to generate a random number with given restrictions: It will be used in a decentralised network with a big number of peers (no central authority to generate it) Its generation should ...
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3answers
174 views

SRP-6 vulnerabilities when N is small

I'm one of the developers of an application which uses SRP-6 as the authentication mechanism. The authentication part of the code is very old and uses N with only 256 bits (all arithmetic is done in ...
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481 views

How does using salt reduce rainbow table attack?

I could create a rainbow table for a particular salt value and still create a successful attack similar to one without salt value.
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181 views

Importance of salt when deriving an encryption key

I'm very curious to know this and a bit confuses too: Suppose, I have two files encrypted using AES-128bit with keys PBKDF2-derived from the same password and the same salt. If an attacker does ...
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Is there a cryptographic function or system in which it becomes HARDER to break as time passes?

Is there a function or system which is time depending in which the effort required to brute force the decryption increases with time? It is easy to break encryption from many years ago because ...
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How to account for moore's law in estimating time-to-crack?

It seems to be common practice (at least in some communities) to tack on the phrase "with current computing power" when estimating the absurdly long time it would take to, for example, brute-force an ...
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1answer
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Clarification of the terms “brute force” and “guess”

In the answer to the question “What exactly is a negligible (and non-negligible) function?” There is a part in the explanation that – as far as my knowledge goes – is conflicting: But instead of ...
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Using PBKDF2 twice with different argument order

I'm pretty sure this is a really bad approach (in theory), but one of my clients is doing this and I was wondering… How bad it is to perform pbkdf-2 in this way (with 2000 iterations)? ...
3
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1answer
399 views

Calculating amount of time for brute forcing ciphertext depending on the size of the key

I am a graphic design student and for my information graphic project I have chosen the topic of the history of encryption and how the security level developed over the centuries. It’s basically an ...
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Uncompress password protected WinRar file without password

I would like to know how to extract contents of the password protected WinRar file without the password. I have downloaded that WinRar file from a file hosting website and found out that it was ...
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1answer
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Can 64-bit “PRINCEcore” practically be brute forced?

There is a cipher called PRINCE proposed in ASIACRYPT two years ago. See the paper: “PRINCE – A Low-latency Block Cipher for Pervasive Computing Applications” The cipher divides the 128-bit key into ...
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1answer
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Is there a time-space tradeoff attack for breaking symmetrical cryptos?

Is there any known techniques for using time-space tradeoff for speeding up symmetrical crypto breaking? Kind of like rainbow tables speed up breaking hashes by using huge precomputed tables. Is ...
3
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2answers
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Is prime regeneration necessary for every new session using a Diffie-Hellman key exchange?

As I understand it, bruteforcing a Diffie-Hellman generated secret key takes $P-1$ attempts to crack the shared secret, where $P$ is a very large prime used for modulus. If your $P$ is quite large, ...
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1answer
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SHA-256: (Probabilistic?) partial preimage possible?

Currently busying myself with the Bitcoin "mining" algorithm, I am wondering if the process really cannot be simplified. For reference, the algorithm is basically SHA-256d: $success := SHA256( ...
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Is 80 bits of key size considered safe against brute force attacks?

I came across KATAN Family of Ciphers for small domain input blocks . They cipher arbitrary block lengths 32,48,64 but their key size 80 bits only. Is 80 bits of key size considered safe with ...
2
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1answer
238 views

Brute force attack expected running time

I am a bit confused about the expected running times of brute force attacks on different cryptosystems. So let's assume a key size of $2^n$ bits. Symmetric key cryptography: $E(brute)$ = ...
2
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2answers
155 views

Is there a metric (term) for work required to decrypt a public key?

Any public key decryption can be decrypted given enough time and computing power. Is there a metric or term for this? Something like it would require on average 2^43 1024 bit hashes to find private ...
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Decrypting files with an unknown method but a known result

I am assuming there is a very simple way of working this out by brute force, but I am not sure if there is a better way. I have a file of data that I wish to get (my data, generated by a machine). ...
4
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1answer
267 views

Brute Force on 3DES with Reduced Keyspace and Unknown IV

I'm trying to brute force a 3DES problem given a reduced keyspace (ie I know the first half of the key) but with an unknown IV. The code decrypts to plaintext. My first thought was that I could set ...
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Decryption honeypots

When performing a key search, I've always wondered how you reliably detect a successful decryption once you hit the right key. I assume that you have to analyze the data and look for patterns: words, ...