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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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Substitution Permutation Network [closed]

Can someone solve this question because I'm brand new to SPN and self studying :)
Amr Ahmed's user avatar
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Question about error-Correction Code on Paper titled 'A New Public-Key Cryptosystem via Mersenne Number"

I've been implementing a cryptosystem outlined here, which relies on Mersenne Numbers, as part of my coursework in a Cryptography class. In this cryptosystem, both encryption and decryption require ...
Nuno Marques's user avatar
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Reaching the bound of Boneh and Durfee Attack

According to the paper, theoretically,we can get $\delta=0.292 \lt 1-\frac{1}{\sqrt{2}}$,but how to set the lattice and implement it in sagemath? I generated some data by ...
Cred Mao's user avatar
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42 views

Decrypting Message Using One-Time Pad with Repeated Key [duplicate]

I'm trying to decrypt a message that has been encrypted using a one-time pad with a repeated key. The encryption technique involves using the same key twice. We know the message was encrypted with $k =...
crypTOl23's user avatar
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2 answers
154 views

Is it possible to perform reverse rsa encryption ? (using the public key for decrypting and the private key for encrypting)

Simple question, but I couldn’t find an answer as I know about signing but don’t want it. The aim would be to encrypt someone’s bet parameter as a short message using the private key and use the ...
user2284570's user avatar
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Homomorphic Decryption with the Encryption (ciphertext) of Secret key for Bootstrapping purpose

The section 3.1 of the GHS11 mentions that: Given the $q_L$-ciphertext $c = (c_0, c_1)$ (that encrypts a polynomial $a \in F_2[X]/F(X)$), we postprocess it to get $c^\prime = (c_0 + c^*, c_1) \text{ ...
kindi's user avatar
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2 answers
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Can I change the radio frequency according to my encryption algorithm?

I know that information can be changed by changing the frequency of electromagnetic vibrations.My question is, can I change the frequency according to my encryption algorithm? That way I can get a ...
Hacer's user avatar
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1 answer
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Cartesian Product Notation for Encryption and Decryption

I'm learning about encryption $(E)$ and decryption $(D)$ algorithms and am wondering what the following notation means, specifically the cartesian product for $E$ and $D$. $k$ represents key, $P$ ...
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2 votes
1 answer
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Decrypting 3 Binaries | LFSR

I have three binary arrays each one representing the pixels of an image. For example, if the picture size is 100 pixels X 100 pixels. Then the binary array would be 100×100×8×3 bits. These files are ...
Ahmed Diyaa's user avatar
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2 answers
322 views

Is it faster to decrypt than to encrypt in all cryptography systems? [closed]

I am using a cryptography system in which the Feistel structure and permutation cipher are combined. I am amazed by the result; decryption is so much faster than encryption. My system is working ...
Dharmendra Thapa's user avatar
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Speed comparison of encryption algorithms

I am trying to compare various encryption algorithms in terms of encryption duration, decryption duration, information entropy, NPCR, UACI, and correlation coefficients. I used a Lena 256x256 ...
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Finding bit positions of '1' in DES Encryption

In DES encryption, the IP table is shown. If the input given in hexadecimal is "0020 0940 0000 F008", which are the bit positions of "1" after the IP stage ?
Bassel 1000's user avatar
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Finding plain text given two cypher texts of the same plain text with two diffrent public keys

I want to find the plain text from two cyphertexts of RSA, encrypted with two diffrent public keys. I know that: for E((n,e),m) = c0 and E((n,f),m) = c1 , c0^x . c1^y mod n = m mod n = m (ex + fy=1) ...
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Is it possible to deduce the input of a hash by running in reverse? [duplicate]

If i understand correctly, hashes run a defined set of operations iteratively until the original data is all hashed. Can you take a hash value, run it backward through the last step (or once, for an ...
Zekchelovek's user avatar
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Does higher key sizes correspond to a higher security parameter?

If a system provide n bits of security, it is known that the best possible attack against the system would be 2^n (security parameter). However, why are the key sizes of some cryptosystems much larger ...
rin ichinose's user avatar
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Syndrome Computation Patterson's Algorithm

Suppose in Patterson's algorithm for the correction of binary Goppa codes, we wish to compute the syndrome polynomial when the defining polynomial is $g(x) = x^{4} + x + 1$, and the error polynomial ...
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Enigma - Bombe - Understanding the relative values of ring settings to key settings

For a project, I am writing Enigma and Bombe simulators in Python. I have coded up both and so far so good. My Enigma simulator gives the same results as the online simulator here: https://people....
Andy Robinson's user avatar
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Decrypting AES-128 with known regularly spaced single byte value [duplicate]

How would knowing a clear byte value of the decrypted data affect a brute force attack on an AES-128 encrypted message ? i.e. If I knew the 1st byte should decrypt to 0xff OR I knew that every 100 ...
D.Price's user avatar
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1 answer
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What is the inverse of this variant of the Gimli SP-box?

Consider a slightly modified variant of the Gimli SP-box: ...
lyrically wicked's user avatar
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1 answer
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What is the inverse of this generalised automaton (based on bitwise XOR and modular addition)?

Section 4.1 of the paper “Nonlinear Diffusion Layers” [Y. Liu, V. Rijmen, G. Leander] defines the nonlinear function $\rho$ over $\mathbb{F}_{2^m}$ as follows: $$\rho : \mathbb{F}_{2^m}^4 \to \mathbb{...
lyrically wicked's user avatar
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Does BearSSL Library Support ECC Encryption/Decryption Functionality?

I'm researching cryptographic libraries for a project I'm working on, and I'm particularly interested in the BearSSL Library due to its lightweight nature. But I'm not sure if it supports ECC (...
IKCekis's user avatar
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2 answers
143 views

From Entropy's perspective how Encryption affects a Message?

How Ciphers, specifically, Substitution Ciphers and Transposition Ciphers manipulate the Entropy of Plaintext w/wo the aid of Entropy Source? Reversely, how Decryption manipulates the entropy of ...
Schezuk's user avatar
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Ensuring Data Security During Decryption and Re-encryption Process

Scenario: Consider a scenario where Server 1 stores a 600-800 KB ebook encrypted with a certain private key. Server 2, a computation-purpose server, holds this private decryption key and get access to ...
JeremyDEX's user avatar
3 votes
1 answer
466 views

On real-time decryption of encrypted radio communications

According to Jack Watling & Nick Reynolds, Ukrainian officers recalled one incident in which the Russian headquarters gave pre-emptive warning to its units of an artillery strike based on ...
Rodrigo de Azevedo's user avatar
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Vigenère cipher SECRET

Decrypt “jjjj aaa cccc ddddd” using Vigenère cipher with the key “CONVO”. I used 2 different generator and online calculator and i am getting 2 different results
Secret Admirer's user avatar
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3 answers
631 views

Encrypt different inputs with different keys to obtain the same output

I'm researching to see if there is an algorithm that encrypts different inputs with different keys to produce the same output. So let's say I have 2 messages. ...
johnny 5's user avatar
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Why is decryption algorithm usyally deterministic?

For security against Chosen Plaintext Attack (CPA), we need randomized algorithms for encryption. But in some schemes (maybe almost all of them) take decryption algorithm deterministic. This procedure ...
user1035648's user avatar
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How do I decrypt a key encrypted by my HSM under a ZMK?

I've generated a key using an HSM Thales PayShield and i have share it with a counterpart. I followed these steps: i generated key usign KG console command i use FK to form ZMK from clear components ...
MaXbeMan's user avatar
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Are asymmetric encryption and decryption same function? [closed]

In asymmetric key encryption, we have 2 functions, encrypt(m,k) and decrypt(m,k), and 2 keys, ...
Juan's user avatar
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How many ciphertexts should attacker intercepts if he only knows the first 3 bytes of plaintext of each one?

Consider a system in which DES is used to encrypt messages in which the first three plaintext Bytes are known by the attacker. How many encrypted messages is it necessary to intercept in order to be ...
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XTEA-based encryption to handle up to 128bit block size [closed]

As learning to be an electronic engineer, my lecturer has requested, based on the original Xtea, to develop the FPGA solution to run 128-bit block size and 128-bit key size cryptography. I have ...
DT Nam LE's user avatar
1 vote
1 answer
121 views

Enigma Questions: Eliminating the can't encode to itself flaw? Maybe not a flaw

I am currently writing a paper in my old age for the fun of it. I feel that the enigma machine had gotten a bad wrap for some of its flaws. I decided to write a machine simulation to see if I can ...
DJ in Colorado's user avatar
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1 answer
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If ChaCha20 only has 128 bits, is it secure?

ChaCha20 also provides 256-bit encryption, i.e, 2^256 possibilities of keys. But ChaCha20 is very fast, I think it provides at most 2^256 multiplied by decrypting time. 256-bit AES provides 254-bit ...
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Why is IV in RFC8448 examples only 12 octets instead of 16?

I am working on manual decryption of application data in TLS 1.3 by going through example in RFC8448. I successfully derived and expanded key and IV, but the IV in examples is only 12 bytes long ...
miran80's user avatar
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1 vote
1 answer
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Can I use Argon2 to encrypt data?

Normally I use Argon2 to generate an encryption key, and then use AES to encrypt data with that key. Can I just set the hash size to be equal to the data size, set the associated data to a random ...
Alice's user avatar
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2 votes
1 answer
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Padding Oracle Attack - Decrypting First Block with Static IV

I'm trying to understand the exploitability of the padding oracle attack, which enables someone to decrypt and encrypt the contents without knowing the encryption key. Can encrypted data with the ...
VitoCorleone's user avatar
1 vote
1 answer
105 views

RSA - plaintext equal ciphertext

Just started learning about RSA cryptography so forgive me if I made any mistakes or misunderstandings. ...
Lykos Angiolo's user avatar
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0 answers
580 views

How can I decrypt a message with RSA if $e = 65536$ and $\gcd(e,\phi(N)) = 8$?

In a message exchange with RSA, an unusual public exponent $e = 65536$ is used. Since $N$ is easily factored, I am able to derive $p$ and $q$. Consequently $ \phi(N) = (p-1)*(q-1)$. However, since $2^...
Jake's user avatar
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4 votes
1 answer
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Where does signing/decrypting take place on a YubiKey 5 for PGP private key?

I have found similar question for PIV (and not PGP) I assume PIV and OpenPGP would work in similar ways. I also assumes that the GPG private key never leaves the Yubikey. If these assumptions are ...
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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 ...
Simon Balfe's user avatar
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0 answers
589 views

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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1 answer
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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. ...
user108142's user avatar
1 vote
2 answers
155 views

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. ...
user108142's user avatar
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1 answer
103 views

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 ...
Yuniel G's user avatar
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0 answers
121 views

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 ...
Fabius Wiesner's user avatar
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1 answer
143 views

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 ...
user997112's user avatar
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1 answer
136 views

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 ...
user997112's user avatar
1 vote
1 answer
247 views

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 ...
user997112's user avatar
1 vote
2 answers
140 views

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....
Abhiroop Sarkar's user avatar
2 votes
1 answer
118 views

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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