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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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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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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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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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452 views

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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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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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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302 views

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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141 views

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 ...
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Encrypt a file in a way that decryption requires every recipient's cooperation

The best related concept I can think of is the two-man rule. https://en.wikipedia.org/wiki/Two-man_rule. To put it simply, n people are required to give their authorization before a system / secret ...
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Can modular multiplicative inverse be used to create a secure cipher?

Let $N$ be a large number; and $(e, d, N)$ be a secret-key; where $e$ is a one-time random factor, and large enough (say the more or less the same number of bits as $N$), where $e < N$ and $e * d \...
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feistel cipher and number of rounds

In feistel cipher , does it matter that number of rounds be 16 ? is using 16 rounds will give the best result ? Or using any number of rounds is the same? in cryptography and network security by ...
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Question on nCPA Security and Uniform Permutations

I feel I am misunderstanding the idea of nCPA security and its relation to uniform permutations. In particular I've been reading the paper "Hoang, Morris Rogaway; An Enciphering Scheme Based on a Card ...
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How safe is a book cipher? How would you break it?

This might not be a very specific question, but I was wondering this morning. If one were to encode a message by making a string out of an entire book and writing the message by searching for a random ...
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Are the following asymmetric encryption schemes equivalent?

Consider the scenario where you want a machine to be able to send daily encrypted backups to a storage server. You'd prefer to not use simply a symmetric key for encryption, because if the machine ...
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How secure is ChaCha20? [closed]

I want to implement a stream cipher to encrypt very sensitive data in my Python code. I heard about the ChaCha20 algorithm and the PyCryptodome library , but how secure is it ?
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Attack on stream cipher that XOR's the output of two LFSRs

There are two LFSRs of different lengths: LFSR-17 and LFSR-25. LFSR-17 Initially contains a two byte seed, with a 1 injected into the fourth bit, for a total of 17 bits. LFSR-25 operates in the same ...
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How can a XOR encryption be cracked systematically?

It's given that a string, encoded in hex format, is obtained by XOR encryption of a plain text and a key. The key is unknown (not even the length). What are the ...
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Why does the Content Scrambling System have two different length LFSRs

CSS uses two LFSRs of length 17 and 25. If we have two periodic functions $f(t)$ and $g(t)$ and consider the function $h(t) = (f(t), g(t))$, then $h$ will have period $pq/\gcd(p, q)$ where $p$ and $q$...
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Finite Automata and Application to Cryptography

The automated inverse theory in cryptography, points to autonomous finite automata, which is relative to the canonical form for one-key cryptosystems based on finite automata, the public key ...
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Encryption wth expiry date

Is there a way to encrypt a file with expiry date? I want to share a file which can be decrypted using a key until certain date. After that date, the recipient should not be able to decrypt the file....
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Encryption using deterministic CSPRNG as secure as CSPRNG

As a beginner it seems that a scheme derived from a CSPRNG should be as secure as that CSPRNG. Is this a correct assumption? Are there restrictions or known special cases? A rough outline would be: ...
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Encrypting/Decrypting sensitive information for storage purpose

I want to store account numbers and routing numbers into SQL database, and i was looking for best way to encrypt/decrypt this sensitive information. After researching i found i can use symmetric (like ...
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3DES Feasibility and Security [closed]

Questions are as following: Is 3DES still feasible (in terms of security and performance) to use? Is 3DES safe to use in ECB mode? Every time on giving the same input (plain text) to encrypt via 3DES ...
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Is there any valuable Cryptography certification for working in the field? [closed]

I'm an amateur math/crypto/CS passionate, but I find myself without any degree or certification that gives credit to my skill-set, specially on math and crypto. Currently I'm designing cryptosystem on ...
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Login security and plaintext of a password stored in Argon2i to derive a key via halite safe?

I'm using Symfony 4. I have set parameters on all my Argon2 stuff below so that it takes 1s per iteration. This website is supposed to encrypt HIPAA information. Basically I have a table like this <...
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Do I need to know the curve for ECIES decryption?

Let's assume that I have key pair generated using the following curves: brainpoolP256r1, brainpoolP320r1, brainpoolP384r1 or brainpoolP512r1. Do I need information which curve was used to decrypt ...
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Can a digital signature scheme also be an encryption scheme?

Using Schnorr signatures, one could devise a system where a single public key can represent multiple signers. Do signature schemes like that represent crypto systems usable for encryption? In that ...