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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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Encrypt twice with DES using same key ? $\operatorname{DES}(\operatorname{DES}(x,k), k)$

Does encrypting with $\operatorname{DES}$ in the following way $$\operatorname{DES}(\operatorname{DES}(x,k), k)$$ make $\operatorname{DES}$ as strong as $\operatorname{2DES}$ with 2 keys? Because we ...
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MTI authenticated key exchange protocol and their vulnerabilities?

Can someone please explain the different MTI key exchange protocols (A0, B0, C0, C1) and their vulnerabilities. I've been trying to read about them but couldn't get much information.
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DES - encrypt 3 times - DES(DES(DES, k), k'), k) - stronger than 2DES with 2 different keys?

What if were to use DES in the following way: For a given plaintext x and key k we will perform: ...
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Homomorphic properties of Paillier

I'm curious about the homomorphic properties of Paillier. So, basically if I have $\textsf{Dec}(\textsf{sk}, \textsf{Enc}(\textsf{pk}, \alpha) \cdot \textsf{Enc}(\textsf{pk}, \alpha^{-1}))$, I will ...
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How much data can I encrypt with RSA before I need to change the key

How much data can be encrypted with the same RSA key before it has to be changed? I looking for the total amount of data that can be encrypted for a single key pair, not the maximum length of data ...
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How could I test my own Cipher? [closed]

I recently developed a new cryptographic algorithm. I just initiated with just nothing in mind. But being near to completion (though my algorithm is constantly developing. Now it is version 11.02), I ...
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How do we know if we have successfully decrypted something?

Suppose for any given typical Bob, Eve and Alice encryption example where Bob and Alice exchange information using RSA. Bob encrypts his message using Eve's public key and sends his message off to ...
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Prove that some Cyphertext C encrypts some plaintext D

I have a Paillier Cyphertext C and a counterparty that controls the keypair that was used to encrypt the data D to arrive at C. How can they prove to me that the Cyphertext C is actually the ...
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Gate count for Ring-LWE

In one of my recent research, I need to compare the number of gates needed in Ring-LWE encryption to AES in the circuit model. For AES we can find some estimation like this site, but for Ring-LWE we ...
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Does it matter whether parameters are inserted in reverse order for Trivium?

I am currently looking into a Trivium implementation available in the FELICS framework. Parameters of the Trivium stream cipher: Key size: 80 bit IV size: 80 bit State size: 288 bit The Trivium ...
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Why is this Trivium implementation working bytewise instead of bitwise?

I am currently looking into a Trivium implementation available in the FELICS framework. Parameters of the Trivium stream cipher: Key size: 80 bit IV size: 80 bit State size: 288 bit The Trivium ...
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Existence of a NIZK proof demonstrating that a ciphertext does not encrypt some specified plaintexts

Given a (El Gamal, for instance) ciphertext, can I (efficiently) prove that the ciphertext does not decrypt to plaintexts in a small set? For instance, given ciphertext $c = Enc(pk,2; r)$, can I (...
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SOTA updates in combination with a Trusted Platform Module

I am quite new to cryptography and security related stuff. We are working on a new project with Embedded Linux on the BeagleBone Black. We wish to implement a full root of trust during boot up using ...
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Decoding a message on elliptic curve

Let's say I have an elliptic curve $E$ $y^2=x^3 + 486662x^2 + x$ over a prime field $GF(2^{255} - 19)$. My algorithm for computing $E(m)$ is as follows: I take the bits 1 through 32 of the message ...
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Why is a proxy needed in proxy re-encryption?

Context Here's the usual proxy re-encryption scenario: Alice, with key pair $(pk_a, sk_a)$ encrypts a message $m$, producing $c = encrypt(pk_a, m)$ Alice saves $c$ on an untrusted storge provider (...
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How to encrypt file with RSA and AES that anyone with RSA key can decrypt them?

How to encrypt a file with RSA and AES-256 that anyone with RSA key can decrypt them?.
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mapping point on elliptic curve

good evening guys, let us suppose that elliptic curve is given by the following equation $y^2=x^3-x+1 \pmod {127}$ on the following table message $9$ is converted to the point on curve if i ...
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Encrypting text using Caeser cipher in CFB mode

I am interested in learning and understanding cryptography and its application in every day life. One thing I can't seem to get my head around is encrypting plaintext using a block mode such as CFB. I ...
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lattice-based key encryption scheme

I would like to ask that is there a lattice-based encryption scheme like the following scenario: There are three users (user1, user2, and user3) own their pk ($pk1,pk2$,and $pk3$) and sk ($sk1,sk2$, ...
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Is one big file as secure as X small files with the same password?

Hello people of StackExchange. It's my first time asking and I know little about Cryptography, so be gentle. My problem can be simplified to this: I can create a 2GB Volume that contains 1GB of text ...
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Is it possible to delegate re-encryption key generation?

In a non-interactive proxy re-encryption scheme, Alice, with the key pair $(pk_a, sk_a)$, needs to issue a re-encryption key $re_{a\rightarrow b}$ once she wants to share her secret message with Bob, ...
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Timings for key schedule

In my Encryption Algorithm (AES for example), How can I know if there is restriction on timings for key schedule or not, and if there is restriction, How can I know what it is?
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Would the Secure Enclaves such as Keystone or Intel SGX obviate the need for cryptography

Would the use of Secure Enclaves such as Keystone or Intel SGX obviate the need for cryptography? Rendering cryptography irrelevant in the decades ahead?
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Can perfect forward secrecy introduce vulnerabilities?

Is it always a win or could PFS algorithms introduce new attack vectors or weaken the level of secrecy vs not being used?
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Why are matrices so common in symmetric encryption?

Matrices have been used in symmetric ciphers since the Hill Cipher (before?) all the way up to modern ciphers such as Twofish and AES. I understand matrices can be invertible, therefore making them ...
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Modifying password-encrypted values to generate new password-encrypted values

Do there exist four functions f, g, Enc, Dec such that: $$f(Enc(x, p), i) = Enc(g(x, i), p)$$ $$Dec(Enc(x, p), p) = x$$ where Enc and Dec are a secure encryption/decryption algorithm (such as AES)? ...
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RSA encryption/decryption process is not working correctly

I'm trying to apply the RSA cryptosystem to encrypt a byte M=72, using predefined modulus n, public key exponent ...
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What is the name of an attack where the compromise of one key compromises the whole system?

Consider the following: A whole system depends on the security of one private key and if this key is, for any reason, compromised, the whole system will be compromised. What's a suitable name for ...
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Is it possible to encrypt a process?

Imagine a hypothetical system as follows: A distributed algorithm running on a Local Area Network (LAN) that allows real-time addition and removal of processors. The addition of a processor is ...
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34 views

What happens if CBC-mode uses the same IV for all processes?

In CBC mode (Cipher Block-chaining mode), each block of plaintext is XOR with the previous ciphertext block before being encrypted. What happens if I use the same IV instead of the previous ciphertext ...
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Encrypting a 64-bit binary number to a text containing upper- and lowercase, and digits

I am making a tool that generates 16 character long password out of a 64-bit binary number. But I dont know how to make an encryption key for that, or where I can find one. To show what i mean, here ...
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JWT Login Security

I am new to security and I am wondering if JWT is secure enough. From what I have read online the flow goes like this: Clients log in by sending their credentials to the identity provider. The ...
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Does hashing an encrypted message suffer from any drawbacks?

I am working on this problem where the set up is like this: There are three hosts: A, B and C. A wants to send a message to C which passes through B. At A the message is hashed, the hash is padded to ...
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Newbie question: one-way functions in cryptography

I'm reading this article on the basics of cryptography and it says that the main principle is about taking such an algorithm that knowing the end result and the algorithm, an eavesdropper wouldn't be ...
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Patent Status & Usability of AE Modes [closed]

Post Structure: Sources Cited Question & Details Before You Answer Useful Info From Comments Sources Cited: https://blog.cryptographyengineering.com/2012/05/19/how-to-choose-authenticated-...
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Double encryption : what method is the best?

Given the block-ciphers defined as follows : $1.$ $C=$ $E_{k1}($$E_{k2}$$(M))$ $2.$ $C=$ $E_{k1{\oplus}k2}$$(M)$ $3.$ $C=$ $(E_{k1}(r),E_{k2}(r$ ${\oplus}$ $M))$ where $C$ is the cipher ...
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Is a PRG more costly than AES or any other encryption standard?

I know that there are many encryption standards that take a key and sometimes an IV, and produces a cipher-text (the most prominent one is AES). These standards usually involve many rounds of addition ...
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Find $F(2x)$ from $F(x) = a^x \bmod p$

Given $F(x) = a^x \bmod p$, where $a$ is a primitive root of $p$, Is it possible to work out what $F(2x)$ or $F(3x)$, etc if you know what $F(x)$ is but not $x$. If you use $F(x)$ then $F(2x)$, etc ...
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What role does Representation Theory play in Cryptography?

Shannon said that every cryptosystem can be expressed as a system of linear equations with a large number of unknowns of complex type. In cryptography groups are used since they are a natural ...
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Ethereum RLPx protocol for inter-node communication - flaws in the encryption

Ethereum uses RLPx/devp2p for inter-node communication. The protocol is encrypted using Elliptic Curve Integrated Encryption Scheme (see ref) Under Known-Issues I found this paragraph: The RLPx ...
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Private Key Sharding - How is it Secure in a Distributed Network?

In a Distributed Network in order for a private key not to be compromised sharding will have to take place off the network, correct? If so: Why is it when a Distributed Network shards private keys ...
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What is the shortest type of text encryption?

I have the following text that I want to encrypt with a password: "This is my secret password: 1234567890" encrypted with AES: SgAHzFc3vluxLqZuzZKg8dzhy918N41SUU1BfBXN8CoEDfVJ0R9hox8PT2jKYA== pass:...
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64 views

Is there any way to track if a ciphertext has been decypted?

Just like the case of a box that has been sealed. We can detect if the box has been opened or not by looking at the seal. Is there any way in cryptography or any encryption scheme that allows this to ...
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What is the meaning of probabilistic polynomial time adversary?

I learned about probabilistic polynomial time adversary, but I have some doubt. Is probabilistic polynomial time adversary referred to those who attack in polynomial time with the form of ...
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How many rounds of encryption is ideal?

I am a newbie to the cryptography world. I am working on a custom algorithm that encrypts the data multiple times and results in a cipher text. It uses a different key in each round to encrypt it. I ...
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How can we compare an encrypted number with a normal number?

I am currently doing a project on privacy preserving encryption using a k-means system and the Paillier encryption algorithm (homomorphic algorithm). I have to send an image of a skin disease to the ...
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Can one design an asymmetric encryption scheme based on any secret sharing scheme? Are they that closely related?

I've seen both asymmetric encryption and secret sharing schemes based on graph 3-coloring, and I'm curious if this is a coincidence due to some peculiar property of graph 3-coloring alone.
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How to encrypt the truth table in garbled circuits?

I'm learning about garbled circuits, and I'm using the following tutorial: Yao's Protocol. I have a questions regarding to construction (encryption) of truth table in garbled circuits. Slide 14 says:...
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What is different below two Ciphersuites?

I have two questions; I need an explanation for the differences of below two cipher suites. How do they work with SSL/TLS protocol? (my main concern first one doesn't have '...
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Multiple encryption using the same key

I am a newbie to this area. I have a program that uses a custom algorithm to encrypt a message. I can encrypt it as many times as I want, but using the same key. I have couple of questions so that I ...