Questions tagged [known-plaintext-attack]
The attacker knows at least one sample of both the plain text and the cipher text.
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Using beginning of TLS ecnrypted data to reveal secret [duplicate]
I have the following question about TLS security:
Assume TLS-PSK protected HTTP with AES256-CBC cipher.
When a TLS connection is established, client sends some encrypted data, where the
plaintext is ...
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Meet in the middle attack - message and key
I clearly understand the story of Alice and Bob:
Alice and Bob are going to use double DES. They know the keys K1 and K2.
Alice sends to Bob the encrypted message c= EK1(EK2(m)). Bob decrypts the ...
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Difference between known-plaintext attack and forward search attack
I am looking at the different attacks on RSA. I came across known-plaintext attack where the public key can be used to encrypt all possible messages until it finds a match on the sent encrypted ...
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Hill cipher cryptanalysis - known plaintext known key size
Hello I want to know how to go about this problem
I know the plaintext "abcdef" and the ciphertext. The key size is 2.
I really can't figure out how to find the key for decrypting and encrypting.
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Can a properly implemented ed25519 private key with public underlying data be cracked?
If the underlying data is public albeit hashed with SHA-512, does that make a difference on the strength of ed25519? Please quantify the extent.
Can ed25519 be cracked after a certain amount of ...
user7024
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Known vs. Chosen (plaintext and ciphertext) and RSA
I want to know whether I can break RSA (textbook) with known plaintext/ciphertext attacks.
Known plain-text
Let $c$ be the ciphertext and $m$ the plaintext.
$$c = m^a \mod n$$
Since all I have is ...
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The difference between these 4 breaking Cipher techniques?
I'm trying to understand the difference between the following and what they actually mean :
Known plaintext attack
Known ciphertext attack
Chosen ciphertext attack
Chosen plaintext attack
Any ...
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JSON AES-128: Security against known plaintext attack
I have a system where I am transmitting JSON messages securely (using for example AES-128), where each message has the same format.
For example:
...
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Java's SecureRandom & plaintext attack?
Java's SecureRandom is meant to be cryptographically secure, and I know part of that means that the output should not be usable to predict further output.
Though, ...
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Do I need to prepare plain text before encryption?
When I want to encrypt chat messages (in ASCII) before sending, whether it brings some bit of security if I add some extra bytes to the message or shuffle it in some way? I can even try to make data ...
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function of crypt called "ICE" [closed]
Using exeinfo, I have identified a function of crypt called ICE.
What is it? How can I find ...
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Can the passphrase of a PGP key be deduced from an old backup?
Let's assume that Bob, at some point in time, has created a PGP (key length and other parameters are not relevant at this point). For some reason, he has chosen a very poor passphrase, for instance <...
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RSA Signature Weak Padding Attack
Assume that we have a message $m$ of size $n$, and it is padded with two 01 bytes in front. Then the signature $s$ is computed using a private key $ks$. Can we ...
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DES — Can I recover the key when I have both ciphertext and the plaintext?
Given a message and DES encrypted form of said message, is it possible to efficiently compute the key used to encrypt the data?
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Find the key to a Vigenère cipher, given known ciphertext and plaintext
I have the ciphertext and the plaintext. Is it possible to know the key? If not, what do I need to find it?
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AES and Known-plaintext attack [duplicate]
Can you help me to finding some papers that shows AES is secure against known-plaintext attack?
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KCV and compatibility with block cipher modes of operation
There has been lately a question on KCV (key check value), value provided by many CRYPTOKI (PKCS#11) implementations. I don't particularly like KCV, but I decided to ask about proper use of KCV.
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Determine the Key given ciphertexts and plaintexts?
Given two sets of plaintexts and their corresponding ciphertexts, how does one determine the key $K$?
The ciphertexts are:
$$C_1= (P_1 \oplus K_0) + K_1$$
and
$$C_2= (P_2 \oplus K_0) + K_1$$
$K = ...
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If I have the unencrypted text and the encrypted text, can I calculate the key?
If I have the unencrypted text and the encrypted text, can I calculate the key? It seems logical based on my limited knowledge of encryption that I should be able to... but it also seems like too ...
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How difficult is it to brute force d in RSA: d = (1/e) mod φ in a CPT attack?
Given that RSA key generation works by computing:
n = pq
φ = (p-1)(q-1)
d = (1/e) mod φ
If I was an attacker who wanted to brute force d, could I brute force d given just the public key, the ...
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Decrypting encrypted files if i have the original files(Plain Text attack) [closed]
I have the following A Encrypted file and the same file in its original(not encrypted) form
Now will it be possible to find the encryption/decryption key by comparing the the above two files are ...
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Encrypting files with known headers
If I encrypt a file of a known format that has a lengthy header (e.g. an XML Excel file), does that render the encrypted file susceptible to a "known plain text" attack? In other words, if the first ...
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What makes adaptive memory attack difficult for the adversary?
On page 11, definition 2 of "Simultaneous Hardcore Bits and
Cryptography Against Memory Attacks", the paper outlines the following steps
(PK,SK) public key and secret key are generated by defender ...
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Encrypting 8 times with 8-bit key beneficial?
I was trying to understand cryptography from the book Information Security by Mark Stamp and I am confused by something.
Suppose that Alice has a secure block cipher, but the cipher only uses
an ...
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Could using sequential plaintext uncover AES key?
I am encrypting a string in a format like this:
...
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plaintext and its encrypted version known [duplicate]
I have a (long) text in two versions, encrypted and plaintext. I think it was encrypted using a substitution cipher method (I'm pretty sure, indeed).
I'm not good in this matter, I know little about ...
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With HMAC, can an attacker recover the key, given many known plaintext/tag pairs?
Given many pairs of $(m, t)$, can the attacker compute the key $k$ satisfying $\text{HMAC}(k,m) = t$? (Assume that $k$ was chosen at random.)
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Attack on DSA with signatures made with k, k+1, k+2
For homework, I'm asked to find the private key, $x$, in a DSA digital signature scheme. In the particular instance, we are given the parameters $p$, $q$ and $g$, the public key $g^x$, 3 messages $(...
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Is a known plaintext, ciphertext, and public-key a viable attack on RSA?
Assume Alice and Bob are using RSA to create a common session key and Cindy is listening, attempting to obtain the session key.
Alice and Bob each have their public- and private-key pairs ($\left[...
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Do known-plaintext attacks exist for public key encryption?
In asymmetric ciphers we publish the public key for anyone, which means an attacker can encrypt any message they want and compare the ciphertext and plaintext without communicating with the owner of ...
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Hill cipher, unknown letter value
I've been struggling on this problem for a while now : the Hill cipher is well-known to be vulnerable to known-plaintext attack due to its linearity. Given a key matrix $K$ of size $n\times n$, one ...
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Can a nested block cipher avoid the meet in the middle attack by using a secret initialization vector for the inner encryption?
It seems to be believed that encrypting twice with a block cipher using an independent key each time is not as secure as you might expect because of the "meet in the middle" attack.
This is an attack ...
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Comparing plaintext to contents of ciphertext
Given an authenticated mode of encryption, when comparing a plaintext string against the contents of a ciphertext, which approach is typically considered safer?
Encrypt the plaintext and compare ...
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Hill Cipher known plaintext attack
I know a plaintext - ciphertext couple of length 6 for a hill cipher where its key is a [3x3] matrix.
Based on what I've read and learned, to attack and crack keys of [n x n], if we know a plaintext -...
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Is it possible to obtain AES-128 key from a known ciphertext-plaintext pair?
I have a file, which was encrypted with AES-128 in ECB mode. I know the format of the original file and know that all files in this format have the same headers. So, I have an encrypted block and the ...
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Shortcuts / practicality of brute forcing block cipher (AES) + ECB with known plaintext [duplicate]
I know the plaintext (26 bytes long) and cryptotext of block cipher (suspected to be AES) in ECB mode. I can generate hundreds or thousands of such samples, but the samples are not arbitrary. What are ...
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What are the dangers of predictable (repeated) plaintext structures?
When using a "good", modern cipher (specifically one that provides ciphertext indistinguishability), is it a problem at all if there is some well-known structure in all plaintexts?
For example, ...
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Other than brute force, are there any attacks on Threefish-512 using only a single known plaintext block?
As per title, other than brute force, are there any attacks on Threefish-512 using only a single plaintext block? Are there any attacks like this in any other cipher?
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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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Is symmetric encryption vulnerable to plain-text-attacks?
Imagine that Bob sends a message to Alice for symmetric encryption to send to Charlie. (Only Alice and Charlie know the key.) Alice sends the encrypted message back to Bob to send to Charlie. Can Bob ...
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What is the difference between known-plaintext attack and chosen-plaintext attack?
I am very confused between the concept of known-plaintext attack and chosen-plaintext attack. It seems to me that these two are the same thing, but it definitely is not.
Can anyone explain to me how ...
Tom Fabregas
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Does the Biclique attack on AES pose a credible risk to its security?
I have heard a lot about the biclique cryptanalysis research on AES, which as far as I know is the closest anyone has got to breaking AES.
Exactly how close did they get? Does this attack propose a ...
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Sending KCV (key check value) with cipher text
I was wondering why it is not more common to send the KCV of a secret key together with the cipher text. I see many systems that send cipher text and properly prepend the IV to e.g. a CBC mode ...
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What is the best way to send two floating point numbers to a server on the internet from a small device such as an arduino?
I was thinking about sending some sensitive data (temperature) from an arduino (AVR 8-bit processor) to a server on the internet.
But I would like to make sure that it would not be possible for Eve ...
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Known Plaintext attack against XTEA?
I'm looking for information on known-plaintext attacks against XTEA. I'm most interested in the worst case scenario: if an attacker has all 8 bytes of input and all 8 bytes of output, how much ...
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Obtaining the key length of a columnar transposition, given a known plaintext word
I'm revising for a cryptography exam at the moment and I'm having some problems with a question.
The question looks for the key length of a cipher given that the word "earthquake" appears in the ...
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Why is AES resistant to known-plaintext attacks?
At least it's my understanding that AES isn't affected by known-plaintext. Is it immune to such an attack, or just resistant? Does this vary for chosen-plaintext?
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Getting the encryption method and key from the encrypted data and the raw data
I have some pairs of plaintext and ciphertext data, from which I need to be able to decrypt the other passwords stored in the database.
The password field typically contains something like
...
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Is it safe to encrypt a public key alongside a message with AES?
If I have a message M and a public key P, and I encrypt them alongside one another:
CIPHER = AES(M + P, aes_key)
Is CIPHER now weakened if someone knows what P ...
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