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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Could completely public passphrase hashes ever be reliably secure?

This is a hypothetical question and I only have a basic understanding of Cryptography. If one were to follow the very best cryptographic practices for storing passphrases, could it ever be possible ...
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260 views

Many consecutive hashes to slow down brute force attack?

I've heard that hash algorithms like bcrypt are more secure because they take longer to complete, and therefore take much longer to prute force, without a noticable ...
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204 views

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 ...
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228 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: $E(brute)$ = ...
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213 views

Hypothetical unknown cipher - security in obscurity?

I'm curious what would happen in the following scenario: Suppose an attacker gets a hold of a cipher-text of sufficiently large length. And suppose he has the means to verify a successful decryption. ...
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1k views

Dictionary attack on pass-phrases on common algorithms

I don't yet perfectly understand the difference between brute-force and dictionary attack since this differentiates one attacking the key and another attacking password: apparently attacking passwords ...
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169 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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525 views

DES Crack simulation

I wish to simulate an implementation of a DES Cracker using verilog. But every paper I read give only abstract hints but no concrete steps or how really to go about it. How is it usually done? For ...
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1answer
1k views

Cryptanalysis Affine Cipher: Brute-Force Search Vs. Meet-in-the-middle

Affine Cipher: $Enc(x) = (ax + b) \mod m$ $Dec(x) = a^{-1}(x-b) \mod m$ For a brute-force key search, we need to do $a \cdot b$ encryptions in the worst case. For a meet-in-the-middle attack, how ...
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212 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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226 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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129 views

Is it possible to find a preimage for a reduced size hash?

Given a message $M$ and a 256 bit key $K$, perform HMAC($K$, $M$) with a 256 bit hash function resulting in: $a$ = ...
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1answer
309 views

Vulnerabilities of encrypting data with known regularities

I need to encrypt data that has a pre-defined header and footer structure, and furthermore the data follows pre-defined patterns. The header and footer structure follow a defined structure but cannot ...
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1answer
187 views

Proof of work for determining whether a number is prime?

I have an idea for a system that would be outsourcing some brute force calculations to many users in hopes of finding divisors of a number. However, there is a possibility that a given number would be ...
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398 views

Generate an insecure public / private key pair

I am looking for a way to generate an "insecure" public key pair. and by insecure I actually mean a pair that is breakable using brute-force (or other encryption) methods. As far as I know PGP ...
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136 views

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, ...
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352 views

Are really, really long passwords any securer than short ones?

Just for fun, I want to encrypt a message that will take about 10 or so years to decrypt. My idea is to encrypt a message with AES-512 with a password one million decimal digits long. Knowing not ...
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146 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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314 views

Brute force a ciphered message? [closed]

I wrote my own cipher to encrypt messages. I would like to test a sample ciphered message to see how strong it is. Are there any tools for such task either in Windows or Linux ?
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242 views

chaining rsa with ecies

In an answer to a previous question it was suggested that one way to protect your asymmetrically encrypted AES-256 keys, from say a solution to prime factorization, would be to chain asymmetric ...
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170 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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1answer
152 views

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
101 views

How does the length of the plaintext affect the cipher strength?

Let the block length 64-bit, 256-bit key, cipher text accordingly - 64 bits. What is the strength of the block cipher, if any unknown attacks, which could reduce its strength. We can only brute force. ...
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2k views

How long to bruteforce a RSA key [duplicate]

Suppose I have a 2048 bit RSA public key, and want to brute force the corresponding private key. I guess there are 2048^16 possible combinations? How long would this take me to brute force with an ...
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1answer
471 views

Brute forcing Cardan grille

Having a "rotating" square Cardan Grill with sides long n cells, how could i determinate the cost of a brute-force attack? How many configurations should be considered to perform an exhaustive ...
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1answer
210 views

Is the following key stretching algorithm as memory hard as I think it is?

I'm having some fun designing a key stretching algorithm that can be implemented in pure Python. It's built entirely out of the standard library's hash functions in an attempt to at least wrest some ...
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3answers
752 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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338 views

Can iterated key expansion in Blowfish slow down bruteforce attacks on small key sizes?

Suppose I have to use 64-bit keys for encryption (e.g. to comply with export restrictions). For this question, assume this key is truly random, and the encryption algorithm is Blowfish. Blowfish key ...
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1answer
542 views

What would be the most effective way to brute force a 16 char AES key?

I have a file that is encrypted in AES using a 16 char string. The string is (a-zA-Z0-9) and .,?!. Also, it only contains words ...
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168 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 ...
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39 views

How does a cracker know if they've broken AES-CBC encryption? [duplicate]

How does a cracker know if they've broken CBC or stream encryption? With hashe cracking one would know because you have the password that you started with to test. But for CBC decryption, you have a ...
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134 views

More technical details on the ongoing (alleged) Chinese cyberattacks [closed]

Recently, there has been quite a lot of news about the Chinese compromising various US weapons systems and stealing military designs through "cyberwarfare". I am reading the news sources about these ...
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189 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 ...
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498 views

One Time Pad Question

I have a ciphertext encoded with One Time Pad. I do not know the key. How can I find the possible keys which when decoded, will result in a meaningful plain text?
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255 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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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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128 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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118 views

The weak link is the password?

Consider a secure modern block cipher like AES/Serpent/Twofish. I hear everyone say that the complexity is $2^{128}$ for a 128 block cipher. But isn't the weak link the actual hashed and salted ...
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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 ...
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197 views

Scrypt's maximum strength to increase entropy of lame passwords

The developers claim that a 6 letter long password hashed with 3.8 second's of scrypt would cost $900 to brute-force. If we use more cycles, how quickly will the brute force cost increase? What ...
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804 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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1answer
61 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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114 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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256 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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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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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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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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2answers
198 views

What is the advantage of an attacker over breaking a 4 digits PIN?

When a hardware system is protected by a 4 digits password, what is the advantage of the attacker into breaking that system? Isn't it $10*10*10*10=10^{4}$? If $\frac{1}{10^{4}}$ is the cost of such ...
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Obtaining a key that's using ice algorithm

I have a text file that has been processed by the SNOW steganography tool that uses ICE encryption. However, I do not know the key that would enable me to decrypt and retrieve the message hidden. ...
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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 ...