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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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Is a single md5 hash a good way to generate an AES key?

This site says how to encrypt data using a password in go using AES-GCM. It says the following: When encrypting and decrypting data, it is important that you are using a 32 character, or 32 byte ...
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2answers
82 views

brute force RSA [closed]

I have a ciphertext c_t and a RSA public key pair (e, n). I also know that the encrypted message is a three-letter word in the ...
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1answer
49 views

Comparing DES and DES-X variation: $Enc(m) = DES_{k_1}(m \oplus k_2)$

I came across this question: Test the security of the following variation of DES-X cryptosystem, which uses 2 keys $k_1$ and $k_2$: $$Enc(m) = DES_{k_1}(m \oplus k_2)$$ (Basically, it uses the 2nd ...
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2answers
63 views

How to ensure confidentiality of an encrypted but public message given that computation power increases?

Say I encrypt a message with the public key of a party whom I want to contact with and then send the ciphertext over an insecure channel. Naturally, an adversary who listens to this channel can ...
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1answer
55 views

How long would it take to crack a double hash if salt and final hash are public?

I have a hash of a file $H_1$ and then I add salt and rehash it: $H_2$. I make my $H_2$ and salt public and I use my $H_1$ as a password. How long would it take for this to be cracked with someone ...
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2answers
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Is the key safe if attacker know the encrypted and decrypted message?

Given an attacker know both the encrypted message (+ an iv) and the equivalent decrypted message, is it possible for him to craft a new encrypted message that could result in a desired decrypted ...
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1answer
54 views

Encryption method that is purposely vulnerable to cracking parts at a time?

Is there a method of encryption where your key is made up of $n \cdot s$ bits, but also such that an attacker would know when they've successfully cracked each $s$-bit part? For example, the full key ...
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1answer
300 views

RC4 password recovery

suppose the password used in the RC4 encryption of a plaintext is an English word of 6 letters that we do not know or forget it . Is it possible to recover it if we only know the ciphertext but not ...
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35 views

How effectively is hard to brute force an AES key? [duplicate]

I know that AES(Rijndael) algorithm uses a 128 to 256bits key. Using a brute-force attack how many tries are required to have mathematical assurance to find the exact key to decode the message(in case ...
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1answer
108 views

Is AES practically unbreakable? [duplicate]

Is AES practically unbreakable? Is brute force attack practical on AES?
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0answers
117 views

Rsa factoring best method and time

I am going to participate in a local challenge where you have to guess the two prime numbers(p and q), they give you a 8 bits number, 16 bits number..., 128 bits number... , 512,1024,2048... and wins ...
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2answers
288 views

Benchmark (hash rate) for SHA-3 (SHAKE128)

To estimate the time for brute-force attack we need to compute keyspace size divided by hash rate, where the hash rate (hash/second) varies depending on the computer's capabilities. The website https:...
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1answer
100 views

Benchmark for SHA-3 (Shake128) [duplicate]

I am trying to find the average of hash rate (benchmark) for SHA-3(Shake128) for a normal and supercomputer in order to estimate the brute-force attack which I can get if from ( keyspace / hash rate )....
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Hash Function SHA-3 [duplicate]

I would like to discuss the minimum input of hash function to consider strong (e.g Shack128 (SHA-3)). I have a mechanism based on SHA-3, but the input is just 40-bit, some friends told me 40-bit input ...
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2answers
49 views

Does applying resources improve time?

A password hash function is applied 12 times to secure a password. If it takes 21 minutes to brute force one application of the hash with the available resources, how long will it take to brute force ...
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1answer
74 views

6 Byte for HMAC in wireless system secure?

A wireless system has 8 byte payload and 6 byte for message authentication. Scheme: ...
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1answer
468 views

Are ciphertext-only attacks on LFSRs possible?

Reading about LFSR, I know that breaking an LFSR by knowing it's design and having enough (plaintext, ciphertext) pairs is an relatively easy task but let's assume we know the design of LFSR and a ...
4
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1answer
140 views

How was this Mersenne Twister seed for a 20-character string known a priori found?

Someone generated a seed for the Mersenne Twister, with the intent of that seed producing this string: "9!dlroW ,olleH"ck,@ Which is 20 characters long. Why he ...
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2answers
470 views

Attack RSA knowing the public key and brute forcing all possible message

Alice want to send a message $m$ to Bob, and encrypt it with Bob public key $K_B$. $A \rightarrow B : \{m\}K_B$ Lets assume I have intercepted $\{m\}K_B$, I know $K_B$ and I know that $m \in D$ (...
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2answers
82 views

Brute force encryption keys base on their length

I need to clarify if my understanding is correct. if I am using 4.2 GHz CPU -one core only- that means: 4.2 billions hertz = 4.2 billion operations per second. (about 2^32) So: 32 bit key : 2^32 \ ...
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0answers
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Decrypt an tex file encrypted with rand() [closed]

Link to encrypted tex file: https://drive.google.com/open?id=1gZCujDYmEL-FZ5o_xBUS-Ng5979HSsZ7 This is my attempt at solving the problem: ...
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1answer
476 views

How to encrypt a short plain text?

I want to encrypt a short plain text (i.e., 30bit), and the requirement is that length of cipher text is the same as the short plain text. It seems that stream encryption methods like CFB-8 ...
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0answers
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Can anyone recommend a fast to encrypt, slow to decrypt, asymmetric non-secret key cipher?

Let me explain; I'm looking for a cipher that does not have a shared or secret key in the usual sense. In other words, any ciphertext can be decoded by anyone - providing they are prepared to ...
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1answer
69 views

Cryptanalysis - Brute force

Are there encryption algorithms based on transcendental numbers? Is it just theoretical or are they implemented in practice? If so, how useful is brute force attacks against them? (My understanding of ...
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1answer
911 views

If a key is used to encrypt that same key, is the computational cost to brute force it decreased?

If a key d is used to encrypt a message m that is identical to the key d, resulting in a cipher c c = encrypt(m, d) = encrypt(d, d) is the computational cost to brute force d lower than if the key d ...
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1answer
185 views

The strength of ECDH public keys with small order

I am trying to get my head around the methods involved in ECDH and am confused by the public keys that are used. Alice picks a random number A from 1 to P - 1 and then computes A⋅g (g being the ...
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3answers
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Why does Birthday attack work only with random messages and not with chosen messages?

Considering unkeyed hashing functions, I studied that the birthday attack can only work generating random messages and not with messages chosen from the attacker, but I didn't understand why. For ...
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0answers
52 views

Are 80-bit keys considered secure as of late-2017? [duplicate]

I've seen a lot of ciphers with variants that use 80-bit keys, like Grain, Trivium, KLEIN, KATAN & KTANTAN, Piccolo, PRESENT, RC4, Skipjack, and TWINE. Some of these designs are younger than six ...
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53 views

S-box Brute Force Space

For an 8x8 S-box, as per my calculations, there can be $2^{259}$ possible substitution boxes. I am not considering S-boxes with certain properties, I am only calculating the entire space possible (...
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1answer
58 views

what is the minimum number of keys one would probably use in his brute force attack?

what is the minimum number of keys one would probably use in his brute force attack, Given info- The Algorithm uses a blocking technique where the ciphertext from one block becomes the key to the next ...
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1answer
138 views

weakness of a DES enhancement

The following key enhancement to DES was proposed in order to increase the complexity of finding the keys by exhaustive search. $$\text{DES}^V_{k,k_1}(M)=\text{DES}_k(M)\oplus k_1$$ where the keys’ ...
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Is there an advantage to “weak” hashing and stretching over strong hashing?

Is there any sort of practical advantage to using a stretching algorithm such as PBKDF2 on say SHA256 over a straight SHA512 hash? If the purpose of key stretching is to increase the length and ...
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1answer
511 views

How difficult is it to crack sha256(sha256(pin)) with a 6 digit pin and no salt?

My friend forgot the password to his electrum wallet but knows that it's a 6 digit pin. I looked into it and from what I can find electrum uses the sha256(sha256(pin)) to generate the key used to ...
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2answers
141 views

Can a hash of the original plain text file be used to brute force an encrypted copy?

I have encrypted files stored on a public cloud, in the same directory on the cloud I have the sha256 hash of the files before they were encrypted in a text file. The keys used to encrypt the files ...
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1answer
114 views

Exercise: recognizing Hawaiian plaintext

I was given the following exercise to solve: The Hawaiian language consists of 12 letters. There are 7 consonants: HKLMNP and W and there are five vowels: AEIO and U. In a word, no two consecutive ...
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1answer
220 views

How many time does a SHA-1 computation require on modern CPU/GPU? [closed]

I am considering how long a SHA-1 computation will need on modern CPU/GPU's. Just in case we are interested in brute forcing and consider the birthday paradoxon, then we need consider the SHA-1 output ...
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3answers
639 views

How confident can we be that nobody will crack a 128-bit key?

In a context involving a block cipher like AES-128, excluding quantum computers, cryptanalytic breakthrough on AES and implementation attacks (poor TRNG, DPA..), and wrench, how confident can we be ...
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1answer
3k views

Decoding an MD5 hash where I already know most of the string [closed]

Let's say my friend has made an md5 hash of an email address and sent it to me. The email address will be something like 'jessica_XXXX@gmail.com', and I know it begins with 'jessica_' and ends with '@...
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1answer
330 views

Brute-force attacks practical limit

My question is about practical limit for brute force attacks. As I know 3DES with 56 bits key length can be broken via brute force. I also heard the same news about 64 bit key length (correct me if I ...
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3answers
511 views

DES Bruteforce attack and false positive keys

I have read that a bruteforce attack (regardless on which block cipher is used) can lead to a false positive if key space is greater than blocks space. It is pretty clear to me that is due the pigeons ...
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0answers
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Triple DES: Does knowing the plaintext limit my keyspace for brute force?

My goal is to try and decrypt a single 8 byte block of a Triple DES encrypted data block and in doing so discovering the 8 byte keys that were used. This is mostly an academic exercise but could ...
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2answers
234 views

Is multiple hashings of a cryptographic hash function an acceptable way to increase complexity?

Is nesting/re-hashing a viable way of slowing down a fast cryptographic hash function (such as SHA-256) to slow down brute-forcing attacks on shorter passwords? The use of longer passwords would of ...
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1answer
74 views

Increasing the brute force search time by repeatedly using an an all-or-nothing transform as padding [closed]

I'll explain some extra steps I'd like add to the example given in this document, to further slow down each brute force key attempt, and then you guys can tell me why it wouldn't work. As an ...
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4answers
14k views

How long would it take to brute force an AES-128 key?

How long would it take to crack a AES-128 key using the most advanced technology currently available? The hardware can be anything, be it a high-performance CPU, GPU or even FPGA?
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2answers
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Making brute force attacks less effective through obfuscation?

This page on Wikipedia states "Brute-force attacks can be made less effective by obfuscating the data to be encoded making it more difficult for an attacker to recognize when the code has been ...
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2answers
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Brute force, get AES keys by multiple plain-texts with their cipher-texts

I know that the encryption is AES, and I have multiple plain-texts with their cipher-texts, I don't know the encryption mode (ECB, CFB, etc ...) actually, but I know that the keys and the IV Key (if ...
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1answer
903 views

How to know the type of encryption method

If I have a program that take a string to give me the ciphertext, nothing stored, using the same keys. The ciphertext is a base64. Can I figure out the type of encryption by the amount of characters ...
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1answer
35 views

Guaranteed decryption time schedule

Suppose you want to store information in, say, safe container for a certain time, after which you want information to be accessible. Let's assume simple idea and fill details by yourself. Take some ...
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2answers
1k views

Would SHA1 be broken by sheer brute force, even if it had no weaknesses of its own?

It is well-known that SHA1 is broken. Collisions have already been achieved. Current algorithms for finding collisions leave a “fingerprint” in the collision files, which can easily be detected. It ...
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2answers
160 views

Is it possible to unroll stacked XOR'd strings without brute-force?

Given: An initial string (sBase) that is visible to EVERYONE sBase = "syLgETsPihVXBRuVR4eI" Several other strings that are only visible to ME ...