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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Is TOTP or a timestamp encryption a better timestamp-based authentication token system?

Are there advantages to using TOTP over encrypting a timestamp with a shared secret, in cases where the readability or ease of typing the token are not important?
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Does Encryption add difficulties to File Recovery?

Seems Yes. People always tell us, it is very hard (or almost impossible) to recover an encrypted hard disk. But after a second thought. I think this is not true. Given that we know the KEY, and the ...
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How to construct the blind factors in practice?

I'm Implementing a protocol that uses masking techniques (or blinding factors), so we can mask a value $y_0$ as $m_0=y_0 \cdot r_0$ where $y_0 \in \mathbb{Z}_p$ and $r_0 \stackrel {R}\leftarrow \...
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What are “encrypted instruction sets”?

In 1999, a news article (Careless mistake reveals subversion of Windows by NSA) discussed "encrypted instruction sets". What exactly are these? Please provide a link so I can find more information. ...
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Generation of Rijndael S-box

I'm an electrical engineering student and was doing a brief research regarding the round transformations of the AES-128 and came across the Wikipedia article describing the generation of the ...
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Does the size of the cryptogram affect the possibility of breaking it?

Does the size of the cryptogram affect the possibility of breaking it? In the context of symmetric and block algorithms. Does the format and earlier processing of the document (compression, changing ...
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Making a cipher non-malleable using move-to-front transform?

NOTE: By malleable/non-malleable, I mean the ability/or not to change a byte/block of the ciphertext and have it change only that byte/block of the plaintext. I understand that we use authentication (...
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Hill cipher concepts

I have some questions about the Hill cipher. There is a rule for key K: Determinant of matrix and number of characters of the alphabet must be coprime. What does ...
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Why this isn't a secure PRF?

Given that F is a secure PRF in the example $$F'(k,x)= F(k,x)\mathbin\|F(k,F(k,x))$$ I'm not sure why this isn't a secure PRF? Under what condition $F(k, F(k,x))$ when concatenated to $F(k,x)$ the ...
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Cryptography that lets you conceal a secret, but also alerts others of the exposure of the concealed secret?

Is there such a cryptography where I can prove that someone decrypted an encrypted string? Say I wanted to attach a Bitcoin private key in some type of digital container, but in order to open this ...
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Encryption and decryption of Request and response for REST API

I am working on encryption/decryption for the rest of the API. The client here can be mobile, desktop, web browsers, etc and all the requests will be made to an https endpoint. The main goal here is ...
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Zodiac unsolved 340 cipher decryption in 2020

This is a rather general question, but I'd really appreciate your (experts, in my view) opinion on this subject. I was wondering if, using current tech like machine learning, quantum computers and ...
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How to store the ciphertext generated by the paillier encryption in a pixel?

Goal: I want to implement a paillier algorithm to encrypt images and hide some data reversibly. This is the paper that proposed this algorithm: https://www.sciencedirect.com/science/article/abs/pii/...
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Looking for an algorithm to encrypt with a single key and decrypt with a lot of keys without consuming too much space

Is it possible to have an encryption scheme that could be encrypted with a particular key, then decrypted with a large amount of keys without massively inflating the size of the final result? I am ...
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AES encryption for repetitive small data packets

I'm trying to implement simple AES encryption for small data packets (8bytes, fixed length) being sent from nodes with very little computational resources. Ideally the encrypted data would be a single ...
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Is there a name for strong human-computable encryption schemes? Are there definitions for “human-computable”?

Background: There is some interest in encryption schemes meant for humans to perform without computational aid. (Relevant questions here, here, and here.) People often cite the VIC pen-and-paper ...
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Generating a recovery phrase for a RSA key-pair

What is an optimal way to associate a RSA key-pair with a recovery phrase/seed for access recovery purposes? I've seen a lot of cryptocurrency wallets provide this feature, however, I'm not looking to ...
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Using the hash of the user's password for encrypting/decrypting an E2E encryption/decryption key: is this good practice?

I am developing an app in which the user data is encrypted in the client before the data is transmitted (over SSL) and decrypted after it is received. If the database is ever compromised, without the ...
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Key-Privacy in Postquantum Public-key Encryption

is there any post-quantum public-key encryption that achieves "key-privacy" (IK-CPA, IK-CCA) as described in this paper? I saw one code-based public-key encryption construction, but I wonder if ...
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Prove how to brute-force the double encryption with complexity 2^57 rather than 2^112?

We know that DES has key length that is too short to defend brute-force attack. One idea to improve DES was to encrypt a message using DES twice with two different keys. Let E be the encryption ...
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57 views

How to encrypt a message such that it cannot be decrypted before a certain time?

Suppose you have a message $m$ and you want to design a protocol that produces an encrypted message $c$ such that it cannot be decrypted before a certain time $t$ has passed from the encryption. How ...
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Difference between LRW and XEX modes

LRW and XEX modes of operation look similar. They are both tweakable narrow-block encryption with XORs before and after each single-block cipher. I didn't really get the point where they differ or ...
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Is there a crytographic scheme for “ciphertext consistency verification”?

I a problem that essentially boils down to the following: There is raw data, D, encrypted with key K (call its encrypted form <...
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How to maintain the width of the cipher image in ECC Image Encryption from Singh and Singh (2015)?

I am a beginner in cryptosystems and I hope I would be accepted in the community. I was trying to implement Singh and Singh (2015) ECC image encryption algorithm on Matlab. I have been able to ...
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Review: peer-to-peer encrypted communication

I'd like to ask you to review security of the following communication scheme: network is strictly P2P, based on DHT (peer discovery) root user can create a virtual private network (network private ...
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basic Shamir's secret sharing scheme

I have tried to look online in various sites and texts and tried to use several youtube tutorials but I still cannot grasp it correctly. could someone please help me understand a simple case ...
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What is the exact algorithm for encryption and decryption with hummingbird-1 cryptography?

I have really googled the entire internet but could not find a clear algorithm for hummingbird-1 cryptography.The problem emerges in the decryption module: What is the initial value of state register ...
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Comparison of end-to-end encryption and TLS

I am writing a comparison paper about security of electronic communication and I want to compare end-to-end encryption and TLS by giving two examples such as Whatsapp and Facebook Messenger. However, ...
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How decode works in CCA1 scheme based on MP12 construction?

In Section 6.3 from MP12 we have that $encode(m) = Sm$, for $S$ any basis of $\Lambda(G^t)$. Then I have: $S = \begin{pmatrix} 1 & 2 & 4 & 8 & 16 & 32 & 64 & 128 & 256\...
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Can we use the same frame counter in A5/2

Let we have three encoded messages with length $3*456$ bits in A5/2 encryption. Can we use the same frame counter in the encryption process or we must use different? (E.g. this because in the below ...
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Break an encryption made with XOR of a key and a known Nonce

My questions is general, but in my case regards the Kerberos protocol and the communication between the client first message and the KDC. Is there some problem in encrypting using a: (secret key XOR ...
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266 views

Triple Diffie-Hellman and MITM

While reading about Triple Diffie-Hellman, I was wondering how it can prevent MITM if the server decides to spoof key sets. For example, Alice and Bob are connected using a server. Alice ----- ...
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How do I calculate the conditional probability of a Caesar cipher?

I have a frequency distribution of letters for the plaintext and the ciphertext. I'm trying to determine the conditional probabilities to identify the plaintext/ciphertext pairings. If I encrypt ...
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Decryption of Vignere cipher by hand using Kasiski examination

My task is to decrypt the following message, which was encrypted with a Vignere cipher of length 4: ...
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Creating nested messages in OpenPGP

I need to create a nested message in OpenPGP (my understanding is that the protocol itself should support it). Let's say I have Payload ("Time in Lordran is ...
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attacks and defenses on multi party Diffie-Hellman protocol

I tried to create a 4 partied Diffie-Hellman implementation for 4 people using its cyclic group property. However, I am not sure regarding those 2 issues, and would appreciate if you could elaborate ...
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How to upgrade encryption version of many large files?

Assume that I operate a user-facing online file syncing service that offers end-to-end encryption of large files, such that files are encrypted client-side first, then uploaded to the server for ...
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AES CTR - Pause and resume encryption?

I am using AES/CTR/NoPadding to encrypt while downloading files in one of my application. The encryption is done along with downloading. When the internet is not available in the middle of downloading,...
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What does the server do on receipt of a one-time-password?

I'm trying to understand this question and I do not understand part of it. I have part of figured out, part of it not. Considering the hash function h(i) = (i + 5) mod 7, used in an implementation ...
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Is bit encryption enough?

Assume that $\Pi$ is a secure PKE scheme (or other appropriate encryption schemes) with 1-bit message space. And it can be applied bit-by-bit to construct a many-bit encryption scheme $\Pi'$. ...
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Question about RSA timing attack and a Chosen Ciphertext Attack on RSA

I am quite new to the RSA and I have a couple of questions that confuse me. Q1: A Timing attack on RSA can be prevented _____________________________ A. By performing the “square and multiply” ...
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How to encrypt small pieces of data (2 - 4 bytes) within Beacon advertising packet?

I'm developing a medical device that operates under extreme low-power constraints and transmits data with BLE, where every unnecessary millisecond of air time matters. I am developing a Beacon ...
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What if an AES Whitebox 1024-bit (or larger key) is created? Does it increase complexity consistently?

Following the Chow et al paper and Muir's tutorial, I was able to implement the AES algorithm using tables embedding keys of 128, 192 and 256-bit sizes, later extended to 1024, 2048 and 4096-bit sizes....
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Are biases narrowed towards the provenance of hard NP complete problems relevant?

I hear of randomized reduction, deterministic reduction and non-deterministic reduction of complexity from A to B problems. This could make things impossible for polynomial time adversary prying into ...
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asymmetric encryption with rekeying in an untrusted environment

Alice can retrieve asymmetric encrypted messages (let's call one of them C1 and the Message itself M) for her from an untrusted environment (let's call it Eve). She owns her private key K1 and has ...
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Filling an encrypted disk

For a full-disk encryption setup, with a physical disk X and the induced logical volume X_crypt, there are several ways to initially fill the disk: (A): Fill X with zeros; (B): Fill X with random ...
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RSA encryption extremely large public exponent

I'm trying to do learn a bit about RSA by doing CTF's and now I am doing one problem probably more than 7 hours so I would really appreciate a hint here from an expert. I have an encrypted message $c$...
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Strongswan KDF Test

How can a KDF implementation for IKEv2 application, specifically in strongswan implementation case can be verified for conformance with NIST SP800-135, please? SP800-135 KDF recommendation further ...
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How to break fully homomorphic encryption over integer algorithm with known cipher of same integer?

If I do encryption and decryption like this: Encryption: $\text{E}(m) = (r \times p_1+m) \bmod N$ Decryption: $\text{D}(\text{E}(m)) = ((r \times p_1 + m) \bmod N) \bmod p_1 = m$ where, $r$ = ...
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What is the difference between Google's API-Key, OAuth Client ID and AWS Secure Token Service

What is the difference between Google's API-Key, OAuth Client ID and AWS Secure Token Service? Are they are all just providing delegation tokens, except they are from different companies? Is there a ...

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