# 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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### Difference between fuzzy vault and fuzzy commitment?

https://dl.acm.org/doi/10.1145/2905055.2905118 Quoting the above paper's abstract, "Biometric cryptosystem can apply fuzzy vault, fuzzy commitment, helper data and secure sketch, whereas, ...
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### What is the global resource expense (financial, energy, computing power & time) due to the need for cryptography?

Classic disclaimer: there may be a better place to ask this question, if so comment and I will be happy to move it. An example I'm looking for is related to recent scrutiny over energy consumption of ...
24 views

### Where to store salt for PBKDF2 and initialization vector for AES via WebCrypto

I would like to build secure notes via javascript and webcrypto. I have found the possibilities to generate strong key via PBKDF2 and encrypt data via ...
33 views

### How secure is it to use a 128-bit random seed to derive a 256-bit key for seeding key-pair generation?

We are developing an open-source peer-to-peer app, Mapeo, designed for users with low technical experience (and no email or phone) to collect data in offline environments. We are generating their ...
51 views

### Is it okay to avoid a plaintext IV in AES?

The scenario Using AES 256 with CBC mode. (Authentication is done separately. Ignored here.) The goal (explained more later) To avoid sending an unencrypted IV. But since this is being done using .NET ...
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### Teaching AI a cryptogram and asking it to solve a similar cryptogram on its own

Say that 1 cipher and another are known to hold some form of correlation. Would it be possible to teach an AI one language through the training of a model and allow it to make make predictions on ...
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### How expensive is it to migrate from AES-128 to AES-256

How feasible would it be to migrate from AES-128 to AES-256?
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### what is the decryption version of this encryption python code [closed]

Write a program that encrypts or decrypts a text file using this cipher(simple letter frequency analysis) or the magic-v cipher and write the result to an output file. You should allow the users of ...
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### Construction of S-Box in PRESENT

I'm currently working on an hardware implementation (with verilog) of PRESENT-80 for research purposes. Due to our goal to strengthen the security of PRESENT-80 with Masking and Error Detection I need ...
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### What are the conditions under which quadratic boolean functions are the same?

When are the following two quadratic boolean functions equal? Is it possible only when a_{i,j}=b_{i,j}? Then, how about qubic, quartic, or degree of d? I need your wisdom.
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### Methods and tools for Plain-text Attacks

I have a data block of about 950 byte (previously encoded in QR code). The data is encrypted with an unknown algo+key. The bright side is: I already know many parts of the message, and I have multiple ...
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### How to convert plaintext to element of cyclic group in Cramer-Shoup cryptosystem

I am trying to implement a cramer-shoup cryptosystem but I don't understand how to work with the plaintext I want to encrypt. From what I understand, the plaintext needs to be converted to an element ...
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### Unable to understand notation regarding Shannon's theorem

the following equation is used to prove the Shannon's theorem by showing the existence of two messages $m_0, m_1$ if $|K| < |M|$ but I'm unable to visualize/understand the probabilities. Especially ...
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### Is it safe to store the hash of a plain text?

When encrypting data, I want to verify that the correct key was entered without hashing it. Is it safe to decrypt the ciphertext and compare the hash of it with the stored one or can the plaintext (...
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### Introduction to Cryptography [closed]

AES is being used to encrypt data transferred over a wireless channel. Unfortunately, one of the ciphertext blocks never arrives at its destination (the others all arrive successfully). What will ...
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### Meaning of "consideration" in the field of blockchain, transaction [closed]

Hi I'm just wondering what the term "consideration" means in the field of blockchain. For example, I didn't understand the phrases "consideration from the node", and "...
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### Is asymmetric decryption guessable?

I am not an amateur in cryptography so this might be a very basic question. I am interested to know if there exist ciphers such that if I encrypt a message with it and then lose first say 300 bits ...
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### Encrypted data sharing in decentralised system

Alice encrypts file using her public key and upload it to decentralised file store (some service). Bob buys access to the file. Is it possible to share decrypted file with Bob without having Alice's ...
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### Why can't we have AES512 or more? [duplicate]

Look I know AES256 is ridiculously secure but to keep aes secure even after quantum computers, I have a concern. Using the Grovers theorem aes can be reduced from 256 to 128 bits for brute force ...
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### Example of exchanging information

I am searching for a simle model that can simulate the following procedure. Suppose that $i$ and $j$ are two agents that each one obtains her state dependets signal $s_i(\omega)$ and $s_j(\omega)$. ...
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### How to ensure the data comes from verified source without using asymetric encryption

I'm building a project that is remotely controlled using LoRa and I want to ensure, that nobody can imitate my transmitter and send packets to my receiver. Just encrypting sent data is not enough ...
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### Encryption mode of operation with lowest malleability/not vulnerable to bit flip attack?

I am trying to choose a mode of operation for encryption which does has the lowest malleability and is specifically not vulnerable to a bit flip attack. My understanding is that PCBC is the only mode ...
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### Linux: Is it possible to encrypt a file so everybody in our organisation can view it? (but no one else) [migrated]

In my organisation we have all s/mime installed in our email clients so we can verify our ID and send encrypted mails. These personal certificates are backed by a trusted server certificate. This ...
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### Multiuser encryption, singleuser decryption [duplicate]

I have an hybrid encryption (RSA, AES) for a file sharing project I am working on, where I use a single public key for encryption on the sender side and corresponding private key for decryption on the ...
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### Why LFSR stream code is not suitable for encryption? [duplicate]

Why LFSR stream code is not suitable for encryption? Is there a special attack for LFSR?
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### Can we use LEGO bricks to construct a cipher algorithm?

I read a paper titled "On the entropy of LEGO", which explains how to calculate the number of ways to combine $n$ $b\times w$ LEGO blocks of the same color. For example, six $2\times4$ ...
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### Simple Key Exchange, One Server

I am trying to better understand how TLS works. I understand in the normal use case you need various random values generated and used in the key exchange, to prevent some MITM reusing a previous ...
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### Are all public key a result of computing g^k mod p

I just read through the text book definition of Diffie–Hellman key exchange. And from what i understand, the public key that is shared based on the protocol is calculated from: ...
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### Is a truly p2p ledger (cryptocurrency) possible?

Is a truly p2p ledger possible, where there is no need for a third party (or a number of third parties) to verify ledgers. Probably a system where the two parties who don't trust each other can verify ...
53 views

### Revoke key without communication between the party who revoked it and the party who is validating

I received a very weird question from someone. I feel there is no solution, It would be great if you guys share your views. There are three people Alice, Bob and Sam and they all work for a high-...
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### ECB... lacks diffusion(?)

I noticed that the wikipedia page for 'block cipher modes of encryption' states, "The disadvantage of this method is a lack of diffusion.", referring to ECB mode for block cipher encryption. ...
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### Is it safe to use AES-CCM only for authentication - i.e. for sending AAD without encrypted data?

We are employing an AES-CCM 128-bit stream-cipher with 7-Byte Nonces and 12-Byte Authentication Tags in a communication protocol. Up until this point there was no need to use Additional Authenticated ...
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### Encrypt/Cipher and Decrypt/Decipher a string with a secret

In developing an app I have a simple use case in where I want to encrypt/cipher a string (it could also be a couple of bytes because it's essentially just an IP-Address). On the output I think it ...
238 views

### Why is possible to encrypt multiple messages within the same stream in AES

I have a standard random key and IV. Then I am creating a cipher using these keys and iv and then encrypt a specific message. Later on, if I try to encrypt another message with the same cipher(which ...
45 views

### Formal definition of mono-alphabetic Substitution Cipher

I am trying to write the formal definition for mono-alphabetic Substitution Cipher. I have tried the following $\mathcal{M}:=$ Set of all possible arbitrary length string of English language text, ...
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### Why is a two-round Feistel Network not a PRF? [duplicate]

I am a student studying PRP and PRF in school, my prof gave us a thinking question: "Why is a two-round Feistel network not a PRF, even while the component function is a PRF?" I've seen that ...
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### An exercise from a textbook

Let $\varepsilon>0$ be a constant. Say an encryption scheme is $\varepsilon$-perfectly secret if for every adversary $\mathcal{A}$ it holds that  \operatorname{Pr}\left[\operatorname{PrivK}_{\...
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### How to have a hash function that maps from a group element to a binary string of a certain size in charm-crypto?

I am facing a problem in programming with the charm-crypto library. The hash functions for pairing group elements in charm-crypto can only map from a string to a specific field: $\mathbb Z_r$, $G_1$ ...
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### Two-way encryption algorithms similar to bcrypt

I'm in need of an algorithm that can perform a very specific task: take a short string, encrypt it using an algorithm which can be scaled to keep up with Moore's Law/has a proof-of-work factor/is ...
102 views

### In general, how do e2e messaging platforms deal with changes to the structure of the encrypted data?

I'm a layman trying to deepen my understanding of crypto and private messaging by building a (proof-of-concept) centralized, end-to-end encrypted messaging "platform". Messages are sent by ...
786 views

### Which block cipher mode of operation does TLS 1.3 use?

Which block cipher mode of operation does TLS 1.3 use? I assume it is a block cipher mode that provides authentication (like GCM).
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### Block cipher design criteria when specifying key size

For a given block size of N bits, the total number of possible permutations is (2^N)! In order to select from any one of the possible permutations, the key would have to be of length log2((2^N)!) ...
87 views

### is there any good attack model of HMAC?

are there any good attack models of HMAC ? like how it can be attacked ? if there are any possible attacks of HMAC i would be happy to know about it.
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### RSA implementation not working with large values for plaintext [duplicate]

While implementing RSA encryption/decryption (using python), the plaintext doesn't match with the decrypted ciphertext for large values of plaintext. Works fine for smaller values for plaintext (...
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### Confusion and diffusion misunderstanding

I am reading the book titled "Algebra for Cryptologists". The author defined the confusion and the diffusion as follows: Confusion: Confusion is intended to make the relationship between the ...
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### What would be the benefits of using a faster cryptographic system with the same level of security as AES

Essentially I'm asking, what if I have designed a quantum-proof stream cipher that is faster than AES-256? Will using less computational power for encryption/decryption be valuable to companies or ...
107 views

### Factoring a RSA modulus given parts of a Factor

e,N,c and around 2/3 of p are given and I need to get the whole p to decrypt c. ...
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### Scheme where earlier hashes provide "hints" to find same or nearby hashes

I am looking for a hash methodology that allows previous hashes to provide "hints" to find same or nearby hashes: if I expect to find a message $M = P + U$ consisting of private $P$ and ...
First, I'm using the settings of https://en.wikipedia.org/wiki/NTRUEncrypt, with $L_f$ set of polynomials with $d_f+1$ coefficients equal to 1, $d_f$ equal to $-1$ and the remaining $N-2d_f-1$ equal ...