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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What kind of transactions that are processed on the blockchain?

I have been watching MIT lectures on blockchain taught by Gary Gensler. What I understand form his lectures is that a blockchain is a record of transactions that it is stored on each computer that is ...
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Public key stored in PKI [closed]

In a public key infrastructure how does a User A communicate with the user B? How does user A send his public key to user B ? Where is a public key stored where do they retrieve it from? This question ...
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Baby steps with example, looking for an "AES for Idiots" type of explanation

Countless examples all over on implementation of AES. None of these actually make sense to someone with zero cryptographic or advanced mathematical experience. This => too abstract & technical.....
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Mathematical formulation for a cryptosystem

I will try to define easily the cryptographic system of this paper. The author designs a communication game for $N$ players. The private information of every player is denoted as $t_i\in T_i$ and ...
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Comparing different cipher text all saying the same thing

How can I compare different cipher text? When deciphered, say the same thing. I would like to find out the ciphering method. Any help would be appreciated. Thanks. The primary code needs to be a 8 ...
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Converting a 32-bit ARX cipher to a 64-bit one, should the rounds be increased?

I read about using 64-bit words in PRF functions. I want to convert the 32-bit ARX cipher Chacha into a 64-bit version, with key/block size of 1024-bits (512*2=1024-bits) My question is: Should I add ...
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Cryptographic Key Management system [closed]

A multinational company has five regional offices around the globe, between which large amounts of confidential data are exchanged every day over the internal network. It also maintains a separate web ...
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Does adding more XOR layers in the XEX block cipher mode increase its security or double it?

I read about XEX mode of operation in Wikipedia My question is: There are two keys that are XORed against plaintext, if instead of two XORed keys I add 4 or 6, does it increase the security of block ...
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Differential Privacy with Outliers

To use the Laplace mechanism, we have to get the global sensitivity of a query function. What do we do in the case where there is one huge outlier(or multiple outliers) in the dataset such that the ...
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Is this a well defined sharing scheme to propose

A proposed secret sharing scheme: Suppose that $p:S\times Y\to X$, with $|Y|\geq|S|$ is a cipher where, $y\in Y$ is the key and $x\in X$ the code, $p$ is bijective, namely $(x,y)$ is associated with ...
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What you think about design of my application? [closed]

I'm building an open source, end-to-end encrypted real time collaborative text editor. My implementation uses the window.crypto APIs in client side JavaScript. I'm quite new to cryptography, so I'd ...
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OPENSSL: What is the command for make cms encrypted data [closed]

I read RFC5652 and I tried make Content types like signed data, enveloped data, and so on. But I cannot find the command cms encrypted data. Openssl has command for it?
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Which solution is the more protected?

I am wondering which of these two solutions is better for security on the long run. The problem is: Alice and Bob exchange a secret key/private key. Then they go far away from each other and never ...
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Could this scheme work for multiparty computation secret sharing?

Suppose that there are $5$ players and each of them learns a secret that is a coordinate of the random vector $s=(s_1,s_2,\cdots,s_5)$, such that $s$ is a uniformly distributed over the field $V$. ...
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Randomness space of encryption function

I was reading the definition of Fujisaki-Okamoto transform, and I found this: What does it mean the "randomness space" of the function Enc in the PKE setting?
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What is wrong with XOR encryption with secure PRNG?

Suppose I want to encrypt a message with a password. Couldn't I just XOR the bytes with bytes from a cryptographically secure pseudorandom number generator (CSPRNG) with seed being the password, or a ...
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How would having multiple independently encrypted versions of the same plaintext impact confidentiality?

Suppose I have some unknown plaintext P which I encrypt N times, each time with a completely new and random key and IV. Would knowing that all the encrypted output came from the same identical ...
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Do symmetric algorithms use "security by obscurity"? [duplicate]

Security of symmetric algorithms rely on "obscuring" keys, correct? They use "secret" keys.
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How strong would be create a password through AES ECB encryption?

Suppose that I want to use a "poor man" password management working as follows: 1. I choose and remember one single master password (for example "78HK+jm?329"); 2a. for any bank, ...
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How are the cipher, the key and the initial message (that is not encrypted) are releted?

Suppose that $m$ is a message that someone player $i$ wants to send to a network of other players $j\neq -i$. The player to prevent his message from cheating by others uses an encyrpstion scheme. Say $...
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RSA - encrypted plaintext results in the same ciphertext value

Just started learning about RSA cryptography so forgive me if I made any mistakes or misunderstandings. M = 20 be the message that i want to encrypt N = 5*7 , p = 5 and q = 7 φ(N) = (5-1)(7-1) = 24 ...
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OPENSSL CMS: Enveloped data's public key, Certificate's public key; Are they same?

I read the rfc5652, and I made enveloped data via openssl: openssl cms -encrypt -in plain -aes256 -recip certificate.pem -outform DER -out enveloped-data.ber Then, I check the public key. First, ...
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Secure multiparty scheme in key (splitting) distribution among the players

Suppose that we have a game with $I$ players and each of them has a private secret say $e_i$. Every player wants to share her secret with the rest of the players but in such a way that she will not be ...
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RSA: The algorithm aside, how are we turning a string into an int and vice versa?

Let's say that I want to encrypt the file plain.txt. The very first step is actually to turn the contents of that file (lets say it only contains the string "...
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Katz/Lindell - 2.10: Is exhaustive search over the key-space allowed in perfect indistinguishability?

I am self studying using "Introduction to Modern Cryptography (2nd edition)" I am trying to understand how the solution to the following problem is valid: Prove that a scheme satisfying ...
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How do you get a Public Key from a Fingerprint

I've seen some people putting their public key's (I'd suppose they refer to a PGP PK) fingerprint on powerpoints and alike so that they can be reached out to using a safe channel. From my POV, it's ...
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Is it possible to cryptographically sign a message with a private key while keeping the pre-image content public?

Essentially, I am looking for a way for user A to create a signed message that user B can 1) verify user A wrote (ie using ecrecover) and 2) the content of the message can be read by user B without ...
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Katz/Lindell 2.4 - Generalizing from 2 messages to any message space?

I'm trying to solve problem 2.4 in "Introduction to Modern Cryptography" (2nd edition) for self-study. The problem asks to prove that perfect secrecy $$ Pr[M = m | C = c] = Pr[M = m] $$ ...
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OPENSSL: What is the difference of enc command and cms' enc command?

I found something strange while checking the inside of the envelope data. I had plain text "plaintextplant" - length is $15$ (include lf(0x0A))`. I made a ...
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How can I enrich this mechanism of communication to become more efficient and secure?

Suppose that we have a Bayesian game, where $t_i\in T_i$ denotes the type of player $i$. Say that we have a communication game (communication equilibrium). The players do send each other an encrypted ...
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Nexor, an encryption algorithm that promises unlimited key sizes: Is it safe?

My intention is not to make spam here, but I came across this project in Github: https://github.com/andrewhodel/nexor It's an algorithm called Nexor, it promises encryption with unlimited key sizes. ...
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How can a cryptographic algorithm be vulnerable?

I was looking for an encryption algorithm to use with my 7zip archives and I read that there is a solution called ZipCrypto that was said to be very vulnerable. Since I'd suppose these type of ...
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Perfect Secrecy for Shift Cipher

I've read the definition of perfect secrecy as the following: A cryptosystem has perfect secrecy if $\Pr(x | y) = \Pr(x)$, for all $x \in P$ and $y \in C$, where $P,C$ are respectively the set of ...
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Sharing information scheme of cryptography - operations in modular arithmetic

Taking into account my previous question here and the answer about the proposed encryption-decryption scheme. I am trying to understand how to make possible operations in modular arithmetic for a ...
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38 views

Protect messages in online messaging system

On a website, I would like to implement a system where users can message each other. The content of the messages should be protected against attackers that are trying to read them. My first thought ...
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Looking for an E2EE protocol

I'm working on an application that allows people to share different types of data with other people that are in the same group. Group limit is 16 people. Logic behind it is very similar to group chats....
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Algorithms for reducing the scope of a brute force attack on a cryptosystem? [duplicate]

I understand that during a brute force attack on a cryptosystem, an attacker is left with many, many, junk files, some which are partially readable (depending on the crypto algorithm used), and 1 ...
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What are some Encryption functions with Poor Confusion

I've recently been learning about Confusion and diffusion related to encryption functions. For the most part I get the gist of what they are but I was wondering if there are any functions with Poor ...
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Split prvate key without Private Key Holder knowing the key shards?

Is is possible to split a private key into shards and distribute the shards to Key Holders such that (1) k of n key shards are required to recover the private key and (2) the private key holder does ...
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Clarification on hybrid encryption vs ECIES vs symmetric encrypt the message and then use assymetric for key

I am trying to understand Hybrid encryption. When I first came across the term I though it is used to describe a scheme where the message is encrypted using a symmetric key, and the symmetric key is ...
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Does Enc and Dec need to be a pseudo-random function for a scheme to be CPA secure?

I am currently going through past finals' questions as exercises for my exam and there are no solutions provided. The question I am currently doing is: Let ∏ = (Enc, Dec, Gen) be a CPA-secure ...
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Can we encode with the set of $\{0,1\}$ and its Boolean operations any finite or infinite domain?

Can we encode with the set of $\{0,1\}$ and its Boolean operations any infinite domain that is subset of the real numbers $\mathbb{R}$ or the whole set of real numbers? For example can we encode the ...
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Security in a pipeline

I am new to cryptography, I am trying to design a secure pipeline environment for the fast transfer of messages. To reduce the Key size I am planning to encrypt the messages with AES session keys (for ...
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Seeking symmetric encryption algorithm optimized for short and human readable ciphertext

In my application, the user logs in when connected to the central database, and their login credentials are authenticated against that data and cached (encrypted). Then, when the user is offline, ...
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Why can't we use the Zeta function to search for prime factors in RSA?

Maybe I got this wrong, but if the Zeta function is efficient to compute and reverse, and if Riemann's assumption is true (which it seems like), can't we use the Zeta function to efficiently find ...
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Risks of Using SHA1 Instead of SHA256 for RSA with OAEP Padding

I'm presently implementing a simple RSA-based encryption as follows in PHP (using openssl_public_encrypt): ...
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How insecure would a cipher based on iterative hashing be?

I was just wondering how the following construction could be insecure. I can tell that known-plain attacks are possible, but I'm not sure about anything else. Let the user pick a password and hash it ...
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Multiplication two points in elliptic curve cryptography [duplicate]

Are there references or prove to say that multiplying two points in the elliptic curve cryptography ECC is not allowed, as an example below? Multiply the public key PKA by a point (Z) on the ECC since ...
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Help: creating secure keys

I want to encrypt my mails and sign them with my digital signaure. I just don't know how/where I get it. what is a good/trustworthy CA? how do I generate those keys? I wanna use EC, which length, ...
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Asymmetrically encrypt a short message into a short string

I have a string whose size is < 32 characters from the following limited character set. uppercase and lowercase Latin letters: A to Z and a to z digits: ...

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