Questions tagged [decryption]
In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Only authorized parties can decipher a ciphertext back to plaintext and access the original information.
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Decode an encrypted text [closed]
I've been doing some reverse engineering challenges online (newbie). And i can't figure out this decryption process.
Your goal is to analyze the given file and help forgetful George to remember his ...
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RSA decryption given C (Cipher Text), e, and d [duplicate]
I am given C, e, and d to decode an RSA ciphertext (or would it be SRA given this information?), and I am thoroughly confused. I have tried working backward to n by reversing modulo operators and then ...
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Differential trails in differential cryptanalysis
From section 4.4 of this book https://www.ic.unicamp.br/~rdahab/cursos/mo421-mc889/Welcome_files/Stinson-Paterson_CryptographyTheoryAndPractice-CRC%20Press%20%282019%29.pdf
I'm confused on how the ...
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Cracking 2-Key Triple DES
I've been given that an attacker has a 2-Key Triple DES Cracker that is capable of performing 10$^{24}$ encryptions per second and have subsequently been asked how long it must take before the ...
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Unable to retrieve the binary string using LWE and Lattice-based decryption
I am new to this encryption scheme, so I may not be exactly sure of its implementation.
I have a list of (u, v) ciphertext pairs to decrypt, each of them are 1-bit.
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RSA Decryption using N without Factorization [duplicate]
So the problem is this Alice decides to use RSA with the public key $N$ = 1889570071. In order to
guard against transmission errors, Alice has Bob encrypt his message twice, once
using the encryption ...
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LWE and Lattice-based cryptography: How to recover binary message $M$ from $(u, v)$ values?
I am given a set of $(u, v)$ values, matrix $A$, primary key vector, private key vector, error vector and prime $q$. I wanted to recover the binary value of each $(u, v)$ pairs using LWE decryption.
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Would it be technically possible to use hundreds of computer processors together to work on an algorithm like the Shor's algorithm and break RSA?
Would it be technically possible to use hundreds of computer processors together to work on an algorithm like the Shor's algorithm and break RSA?
I've been reading about the crazy amount of qubits ...
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Problem in matching AES CTR encryption and decryption with two different engines
I have a problem in combining encryption with a host software tool based on LibTomCrypt sources, then decryption with the hardware BEE (Bus Encryption Engine) of an i.MX RT1062 NXP processor. I am ...
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Implementing AES GCM but not getting correct output from cipher block
I'm implementing 128-bit AES-GCM (but only the encryption/AES-CTR aspect).
When I set the Secret Key, Plaintext and IV to Test Case 2, page 27 of the GCM spec (see below) I get the wrong value for the ...
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AES GCM Difference between the IV and the Secret Key?
Below is part of AES GCM diagram. However, it only shows the behavior of the IV/counter.
The GCM specification examples state both an IV and a Secret Key as two inputs.
Can someone please explain ...
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What is Inverse equivalent (decrypt) in the AES specification examples?
Referring to the AES specification:
https://nvlpubs.nist.gov/nistpubs/fips/nist.fips.197.pdf
Printed pages 35-37...
The first detailed walkthrough is encryption, the second is decryption.... I don't ...
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Reencrypting in Homomorphic Encryption
I am getting started with Homomorphic Encryption libraries. I am trying to port a codebase written in Python to Haskell. I see that there is a re-encryption operation happening in one part of the code....
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Is the XOR two block ciphers still a block cipher?
Let's say I have a block cipher $E: K \times M \rightarrow C$.
Is the function defined by $\operatorname{Enc}(k_1,k_2,m) = E(k_1, m)\ \operatorname{XOR}\ E(k_2,m)$ guaranteed to have an inverse ...
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Designing a scheme to store encrypted data on a backend
My goal is to design an encryption scheme for the application so that the backend stores encrypted data and the whole process of encoding and decoding happens on the frontend. And you can be sure that ...
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Curious about CCA attack for RSA, and Kerckhoffs's principle in general
I'm a student studying cybersecurity for the first time, and the part where our textbook explains using CCA attacks for RSAs seemed really unclear for me, so I am here seeking for clarification.
Our ...
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How to decrypt a RSA plaintext given a public exponent e and a RSA modulus n
I am doing a RSA cryptography task where I need to decrypt a ciphertext but I am only given the ciphertext ,c, a public exponent, e, and a RSA modulus, n, which has two prime factors p and q such that ...
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Possible plain text needed on a congruence modulo - based encryption
Suppose m is a positive integer converted from the plain text in bytes.
And there are two positive integers a, ...
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AES Decryption - Expand Key/First Roundkey
I am wondering how to use and expand keys during the Decryption.
Let’s say we have an initial key (128bits): 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F 70
So we get: w[0] = (61 62 63 64), w[1]=( ...
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'str' object has no attribute 'decode' when decrypt aes [closed]
so i have function to decrypt aes ctr. but when i tried to decrypt, the result i got from plaintext is type bytes. i want to get the result of plaintext using decode, because when i encrypt it, i was ...
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Block cipher decryption
I have a course work for university.
The question is:
My solution to the question is:
P||R = D(K,C)
However, in the question it doesn't say we are given R so ...
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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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How are public and private keys generated and used for encryption and decryption in a lattice based cryptosystem?
I've recently become quite interested in lattice based cryptosystems, and I wish to understand them more deeply. I have only a rudimentary understanding of the shortest vector problem (SVP), and its ...
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Zero knowledge validation to check if private element is in a set hidden on a central server
I am trying to determine how to apply ZK proofs to the asymmetric scenario below.
Say there is a list of 5000 secret elements on a centralized web server.
Users are trying to guess what those 5000 ...
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Reversing an XOR encryption/decryption function
I have a help recommended high-school project that I'm stuck with. To basically explain the problem: I have an encryption function that is used as the decryption function and I need to reverse it to ...
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How to factorize RSA modulus while given two Public Exponents and the difference between two Private Exponents?
The RSA modulus is the product of two $2048$-bit primes.
And the two Public Exponents are both $16$-bit.
I also got the difference between two Private Exponents $\left | d_1-d_2 \right |.$
Is there ...
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value bound of r⋅e for LWE Decryption correctness
For LWE decryption, Someone told me that If we can bound r⋅e by q/4 then we can retrieve M by checking if this is closer to <...
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LWE encryption error
in learning with error encryption scheme (e.g. in Kyber scheme).
there are two vectors:
$u = r^t A + e_2$ and $v= r^t * pk + e_3 + \lfloor \frac{q}{2}\rceil m$
such that $pk = As +e_1$.
my question ...
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Fastest cipher for use with openssl and x86 (Intel)?
I have a C++ application on Intel x86 using openssl to make a connection to a server. What is the fastest cipher that openssl supports? My implementation is currently using ...
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Verifying Password Using Argon2
I am trying to develop a Rest API using Kotlin/Spring Boot. The JSON request in it, should have a hashed password that was done using Argon2id. Getting the password hashed was pretty straight forward ...
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Encryption and decryption for LWE
For https://asecuritysite.com/public/lwe_ring.pdf#page=9 , could anyone explain how the encryption and decryption for LWE work ?
When I do more reading on https://summerschool-croatia.cs.ru.nl/2015/...
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How to perform an attack on similar messages?
Suppose I have two messages encrypted by RSA with the same public key (N, e), where:
M1 = "Hello " + name1 + message
M2 = "Hello " + name2 + message
The names and the message is ...
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Increase encryption key length in Shamir secret sharing
Can Shamir's secret sharing work on any size of key?
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Aes-Gcm how to perform decryption authentication without plaintext output in C#
I'm mainly trying to verify large file chunks which are encrypted each alone with a different key/salt/nonce for each chunk then appended to the whole file in the end to form 1 file.
One thing I ...
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Decryption using multiple keys
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I have a PHP application which calls third party api with username and password embedded in the XML API call from my side.
I would like to encrypt and store the username and password embedded in the ...
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What's the best way to recover an AES-256 key from partial key, ciphertext, plaintext and IV?
So I'm trying to decrypt AES encryption with a 32-byte key. I know the first 7 bytes, and the final 19. I also have the plain text, as well as the IV and the encrypted text.
I'm currently running ...
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How to reverse a CRC-16 from the the entire data? [duplicate]
I am trying to reverse the BLE communications with the Daly BMS (Battery Management System) in order to implement it on my own app.
I already reversed almost all reads and therefore started to deal ...
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How can I reverse a so-called CRC16 from the data?
I am trying to understand a request I reverse engineered which is sent to a Daly BMS over BLE.
Those requests change the 'sleep after' in seconds of the BMS:
For DDDD seconds: ...
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Is there a discrete log challenge?
RSA challenge is well-known and it has a wiki page.
Is there a discrete log for $\mathbb F_p$ where $p$ is Sophie-Germain prime?
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Discrete Logarithm Based algorithm
The private (secret) key in DL (discrete logarithm) based algorithms is uniformly selected from the group Zq*. This private key is then used to compute the public key. Could the opposite be done, for ...
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Can I decrypt AES-CBC ciphertext if I have the key without IV? [duplicate]
Can I decrypt ciphertext from AES-CBC encryption, if I have the key and ciphertext only?
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What's the probability of cracking this cipher using partial information about the private key obtained from $k$ public keys?
For the following cipher, what is the probability of someone without the private key generating a valid public key, using only information from a list of $k$ public keys previously generated with the ...
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Would this hash based encryption algorithm work in theory?
I was just thinking about this and couldn't seem to find anything on it online.
So the idea I had was this:
Generating a random key of some length. Then hashing this key with SHA256 (or something of ...
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RSA / AES issue : Decryption
I perform the following commands because I need to decrypt a file -encryption key file- (which is longer than module):
cat key.enc | base64 -d > encryptedrawfile.txt
openssl rsautl -decrypt -inkey ...
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Does encryption of many files shorten the list of possible passwords?
Hopefully this question is not duplicative, nor its answer too elementary.
Suppose I have a file. I encrypt it, using a password. The password presumably stipulates a pattern or relationship between ...
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How to share decryption ability to others whose public keys are not used during encryption?
as the title says, for example, A uses B's public key to encrypt a message and sent it to B. In later stages, a new member C joins and B would like to let C be able to see this encrypted message (i.e.,...
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Let negl1 and negl2 be negligible functions [closed]
can we still consider the second function negligible ? is there any main differences between them?
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OFB mode discussion
In OFB mode, I understand that a bit flip in $c_i$ for $i > 0$ only causes a bit flip in message block $m_i$. However, how is it possible for a bit flip in $c_0$ (i.e, in IV) will result in all the ...
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limiting number of queries to Enc. or Dec
Why do we limit the number of queries to Encryption or Decryption oracles in the security analysis of various encryption schemes to be polynomial in the security parameter n?
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calculate a tag of CBC-MAC
with a block cipher having a 256-bit key and 128-bit block length to MAC a 1024-bit message. How many evaluations of the block cipher will be performed to calculate the tag?
[Assume there is no ...
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