Questions tagged [encryption]

Encryption is the process of transforming plaintext using a cipher into ciphertext to make it unreadable to anyone except those possessing the key. Decryption is the process of transforming that ciphertext back into plaintext, using the key.

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Metrics for difference/error of output and ideally output

I'm working in some homomorphic encryption for my Ph.D. but I'm not of the field... So I'm possible going to ask a really simple question that I'm struggling to find an answer on the internet. ...
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For Symmetric Cryptography, why is it considered more important to safeguard a key than the function/algorithm for encrypting/decrypting a message?

As stated for the question above here's an analogy: You are a robber looking for a house to rob with two different scenarios that might occur. 1. You have a key that you know belongs to a house and ...
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A semantically secure encryption scheme can not preserve the length of an encrypted plaintext

A semantically secure encryption scheme can not preserve the length of an encrypted plaintext. How to prove this? or are there some methods that can be used to obtain such information from a semantic ...
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Hard to guess ciphertext

Is there an encryption scheme where it's hard to guess a valid ciphertext without knowing the key and the scheme is CPA secure?
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Does sending encrypted hash inside message compromise security

This might sound like a naive question (And maybe it is (It's an early morning Saturday thought, so there might be some clarity of thought missing)). Suppose we havea protocol that sends messages as ...
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Reorderable encryptions [duplicate]

Are there any two encryption function(s) where encryptB(encryptA(data, keyA), keyB) == encryptA(encryptB(data, keyB), keyA). The two functions may be related or ...
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Equality between encrypted hash of data and hash of encrypted data?

Are there any cryptographically strong hash function and encryption function(s) where hash(encryptA(data)) == encryptB(hash(data)). The functions ...
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Proving 2-way nesting security

I recently came across the theorem about $n$-way nesting. It states that if $\mathcal{E}=(E, D)$ is semantically secure, then $\mathcal{E}$ is secure for $n$-way nesting. I'm trying to prove the ...
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Is there still a place for obfuscation (secret algorithms) in encryption?

As far as I know, the Second World War was won on codes that used obfuscation, not open source. These were also used during the cold war. For general use (not large companies with hundreds of ...
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What is meant by software and hardware implementations of cryptograpic schemes? How to do it?

I have read many cryptographic papers or articles where I have came across about the software and hardware implementation for the cryptographic algorithms. I want to know how its been done. Is there ...
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Decryption only on a specified future date?

Are there any encryption protocols or services that are time based. I.e I can encrypt something now and it can only be decrypted on or after 01/01/2100. Like a digital time capsule. The only way I can ...
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Java AES T-Tables Implementation

I am trying to implement an encryption function that uses the AES T-Tables implementation. I am quite sure that my roundKeys are correct. I also know that the initial round key addition in the ...
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Would encrypting several layers of a filesystem be a waste?

I've been thinking about ways to improve the security of my data stored and backed up using the "3-2-1" method. Moreover by using several layers of encryption to encrypt and decrypt a ...
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3 answers
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Zero-Knowledge Proof of Encryption with a Specific Key

Short version: Given a hash of a plaintext, a public key, and a ciphertext (but not knowing the original plaintext), is there any way to verify that the ciphertext is the plaintext after being ...
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Is the SNI extension signed in TLS 1.3?

In TLS 1.3, and since the server signs the entire handshake messages including the server hello message, in this case, is the SNI extension of the client hello message, is it included in the content ...
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Sagemath help: Introduction to Lattices

Hi im doing a problem from the Chapter Lightweight Introduction to Lattices in "Learning and Experiencing Cryptography with CrypTool and SageMath" I'm curious if my implementation is wrong ...
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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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How by changing ciphertext can the attacker know the length of the padding in POODLE attack

I try to understand the POODLE attack. I read that the attacker try to change one byte of the last block of the ciphertext. Becasue the last block is only have padding and the last byte is the padding ...
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Public key encryption with a large number of users

I'm building an app that will primarily be iOS or Android based. My plan is for every user to have their own key pair. The public key will be stored on the server along with a 128 bit UUID which is ...
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MDK vs IMK vs MK key differences

I don't understand whether they are different or not. Would you mind explaining them all? MK-AC, MK-SMI, MK-SMC MDK Encryption Key, MDK MAC, MDK AC IMK-AC, IMK-SMI, IMK-SMC For example, in the ...
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Does exist an Elliptic analogue of Benaloh encryption scheme?

The definition of Benaloh encryption scheme can be found here. Does exist an elliptic analogue of this scheme? I want to use this scheme but the length of the key ...
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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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How to convert a Modular addition to conjunctive normal form (CNF)? [closed]

If I have three integers $x,y,z\in \mathbb{F}_{2^n}$, How do I convert the modulo addition operation into conjunctive normal form (CNF)? $$ (x+y)\pmod{2^n-1}=z $$
mini minions's user avatar
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Does any encryption/decryption algorithm supports linear decomposition?

I am not sure whether "linear decomposition" is appropriate to summary my question: We know that the traditional symmetric encryption/decryption algorithm (like AES, TDES) can be written as: ...
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What is the meaning of X is of order 2N in blind rotation of TFHE?

Could anyone please help me explain this? I am reading the article about TFHE (Guide to Fully Homomorphic Encryption over the [Discretized] Torus). On page 31: I don't understand why we need to scale ...
lap quoc's user avatar
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3 answers
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How big of a threat are *diffusion model* based AIs to cryptographic systems?

The diffusion model, which is used by products like Midjourney and Dall-E, trains AI systems to de-noise (remove added randomness) from data to infer what the original de-noised data is. That would ...
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Non-Gaussian distribution in continuous learning with error

The CLWE problem (and related) talks about the hardness of finding the secret key $\vec{s}$, given polynomially many samples $(\vec{a},t)$, where $\vec{a}$ is sampled from the normal distribution, and ...
Jim Haddocc's user avatar
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What's the best encryption algorithm for storing files on a server?

I'm making a cloud-based service. So, basically, my users will be able to upload files (any type of files) and they will be uploaded to a server. I am aware that I have two options: Upload the files ...
Gaurav Mall's user avatar
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How to break Random Subsitution Cipher that changes key every 16 characters?

Monoalphabhatic Random Subsitution Cipher is pretty hard to crack compared to Ceasar Cipher especially through brute force but using frequency analysis, provided enough cipher text is easy. But what ...
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Finding Inverse Modulo

I'm working on a challenge like this: def weird_func(FLAG) enc_flag = [(a + b*i) % n for i in FLAG] return bytes(enc_flag).hex() Although I know the FLAG ...
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Finding out corrupted S Box value in DES implementation?

I am using DES encryption when writing a file in an embedded device. When I decrypt the file. I get a partially corrupted file. Kind of randomly some 8-byte blocks are corrupted. Some are not. When I ...
Monem Ahmed's user avatar
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Some questions about AES-128 key wrapping using RFC3394

It's that time of the year - I'm trying to learn how AES-128-CBC encryption works. My key is (since it's AES-128) is 16 bytes, my IV is 16 bytes as well. My implementation of key wrapping does ...
Sir Muffington's user avatar
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Kleopatra: What is the strongest and most popular cryptography standard for PGP

While setting up PGP for the first time, I am presented with various encryption standards I can use being: RSA (2048, 3072, 4096 bits) with an option for + RSA (2048, 3072, 4096 bits) DSA (2048 bits) ...
Bill Joe's user avatar
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AES-GCM vulnerabilities

Does AES-GCM take replay attacks into consideration? If an attacker intercepts the AES-GCM secured message and gains access to the initialization vector (IV), can they inject falsely fabricated data (...
udit's user avatar
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TLS 1.3 key_share capture without certificate exchange

I am working on an investigation on TLS 1.3. I've came across an article of qacafe where they shared a TLS 1.3 handshake sequence. Wireshark capture. In this capture you see that in the Client Hello a ...
Arthur Timmermans's user avatar
1 vote
2 answers
329 views

Encrypting random IV in CTR mode (no nonce!)

Use of plain random-IV's in CTR mode, without any special "nonces/counters" (or any "dedicated" bits!), can lead to problems with "partial overlaps", whereby attackers ...
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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
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1 answer
231 views

Is it possible to reverse engineer an encryption algorithm derived from AES-128 given these conditions?

Given the following conditions: The encryption program, which uses some algorithm resembling AES-128 but with unknown modifications to real AES-128. It uses a fixed key and IV. It is written in Rust ...
Sir Muffington's user avatar
2 votes
3 answers
157 views

Long Random Key and XOR - How Secure?

I have an application that encrypts files in the following manner (I think I can hear sighs already but bear with me): Start with two byte arrays generated from random strings of lengths l1 and l2 (...
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1 answer
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Prove with ZKP that I have encrypted a message $v + random\_number\cdot c$ given an RSA public key?

I want to create an application in which users can cast vote to blockchain in encrypted form using RSA. The private key will be revealed only after completion of the election. My major use case is as ...
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Is combining Elgamal algorithm and RSA algorithm for key generation and AES+RSA algorithm for encryption and decryption a novel approach?

Key generation: Key Generation Firstly, the RSA algorithm will be used to generate a public and a private key. Generate two random prime numbers p, q. Select RSA public key, P k such that gcd(P k, Φ)=...
Srity Ahmed's user avatar
1 vote
1 answer
322 views

Is this proof of RSA's correctness sufficient?

In a lecture at my university, the following proof of correctness of RSA is given (the lecture is not mainly on cryptography or even computer science): $m^{ed} \equiv m^{ee^{-1}} \equiv m^{1} \equiv m ...
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Minimal time encryption algorithm for MQTT [closed]

What is the minimal computation time algorithm that I can use for E2E encryption in MQTT protocol which has never been used before
falcon007's user avatar
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1 answer
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How to process a message to be embedded using steganography?

Let's say we embed a text using steganography by modifying an existing cover object. What would be the steps needed to be done on the message? I can think of source coding (compression) channel ...
Martin Benes's user avatar
3 votes
3 answers
130 views

Does the Windows RNG have security problems?

The Windows RNG infrastructure is specified in this article. On page 4, it states that the PRNG called AES_CTR_DRBG is used (with 256-bit security strength). According to Wikipedia, this PRNG has ...
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May I use the same One-time pad key two times if I encrypt it with a block cipher using two different block cipher keys?

Let's suppose I have two 2GiB files and I want to encrypt them using One-time pad (Vernam cipher), but I don't want to store two big keys. May I use only one key for the two files if I encrypt the One-...
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How much of SHA3's internal state can be reached?

After reading that about "37% of the 256-bit outputs" of SHA-256 are unreachable when fed only 256-bit inputs [1] I'm curious & confused. The formula from the proof here considers a ...
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PCD vs Recursive SNARK vs Non-uniform IVC

I was wondering if anyone could clarify the differences between PCD vs Recursive SNARKs(like pickles) vs Non-uniform IVC(like hypernova) They all seem very similar to me
questionman123's user avatar
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1 answer
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Fully-encrypted (non-fingerprintable) symmetric encryption algorithm?

I am a student in the process of creating a firewall circumvention program based on smuggling data inside of legitimate HTTP. I have limited cryptographic knowledge. I need a way to encrypt my higher-...
Temporary Alternate's user avatar
1 vote
1 answer
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Does compressed data expose information about non-compressed data when encrypted together?

I know that compressing data before encrypting it can cause a compression oracle attack such as in the CRIME and BREACH attacks, but if only part of the data is compressed, e.g. non-user controlled ...
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