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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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Parallel block cipher in CTR mode and variable number of threads: how to deal with internal state and permit decryption?

I'm implementing a parallel block cipher (Morus, to be precise) in CTR mode and I'd like to make it flexible with respect to the number of threads. It is not difficult per se, as I can partition the ...
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427 views

Conditional decryption

Is it possible for one party to encrypt some data and have another party (unknown to the first party) view that original data if a certain condition is met? I cannot find any information about this ...
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Can the RSA public key be used for both encryption and decryption?

My understanding of RSA Cryptography is that the Public Key is used for data encryption and Private Key is used for data decryption. But on this website(https://www.devglan.com/online-tools/rsa-...
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Why do we need more security than the private key distribution?

I'm new to cryptography and have question about private key distribution. If we are able to send private keys to the encoder, then it means that we are able to send private keys to someone, which ...
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What is a generalized algorithm to find five $z$-bit words for the inverse of $\theta$ function in the Keccak-$f$ permutation?

This implementation of the inverse of the Keccak-$f$ permutation contains five 64-bit words (called “inversePositions64” in the code) for the inverse of $\theta$ function: ...
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"Appendable" encryption scheme

Are there any encryption schemes that could be classified as "appendable"? By appendable I mean being able to add new data to the end of already encrypted data, without needing to decrypt ...
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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 ...
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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 ...
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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 ...
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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 =...
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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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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 ...
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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 ...
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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{ ...
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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 ...
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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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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 ...
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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 ...
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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 ?
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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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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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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 ...
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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 ...
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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....
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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 ...
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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: ...
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1 answer
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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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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{...
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Decrypt a ciphertext knowing of a pattern of key repetition

I have two ciphertexts (I do not know which encryption algorithm was used to create them) which both starts with the same 3-characters long word. This led me to believe that the same key was used for ...
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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 (...
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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 ...
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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
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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. ...
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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 ...
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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 ...
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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, ...
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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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Evaluate the time of Paillier decryption

If I have 4 kilobytes of Paillier encrypted data, how can I know the time needed to decrypt it?
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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 ...
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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 ...
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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 ...
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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 ...
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 ...
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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^...
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RSA - plaintext equal ciphertext

Just started learning about RSA cryptography so forgive me if I made any mistakes or misunderstandings. ...
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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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Why "encipher" instead of "encrypt" and "decipher" instead of "decrypt"?

According to a book I am reading, Applied Cryptography by Bruce Schneier, the ISO 7498-2 standard uses the terms “encipher” instead of "encrypt" and “decipher” instead of "decrypt" ...

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