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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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New Impossible Differential Attacks on AES reduce time complexity

I am interested in the following snippet from the paper New Impossible Differential Attacks on AES. Analysis of Steps 3–4 of the 7-Round Attack in the 8-Round Attack The most time consuming steps of ...
can balıkçı's user avatar
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Question about error-Correction Code on Paper titled 'A New Public-Key Cryptosystem via Mersenne Number"

I've been implementing a cryptosystem outlined here, which relies on Mersenne Numbers, as part of my coursework in a Cryptography class. In this cryptosystem, both encryption and decryption require ...
Nuno Marques's user avatar
3 votes
1 answer
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Understanding CBC-MAC Algorithm and Nested Encryption

In the CBC-MAC algorithm as given in the image below, I have two questions: It is said that the CBC-MAC is simply the last block of ciphertext if the message is encrypted using CBC block cipher mode, ...
revision's user avatar
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Shannon's Perfect Security for Asymmetric Encryption

I have the following definition of Shannon's Perfect Security. Assuming messages and keys are drawn randomly from some distribution then: The probability of guessing plaintext m is not enhanced by ...
revision's user avatar
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Does truncating a CBC ciphertext result in a truncated plaintext?

I want to know why in the CBC cipher, if we truncate the first block in the ciphertext then the corresponding plaintext block is truncated in the same way. I have an equation for the plaintext $m_i$ ...
revision's user avatar
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improved impossible differential crpytanalysis of 6-round rijndael

I'm studying the paper: "Improved Impossible Differential Cryptanalysis of Rijndael and Crypton". I've got two questions: Please explain the calculation performed for step 5? Step 4 ...
can balıkçı's user avatar
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1 answer
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ECIES encryption time linearity with plaintext size using the same key lenght

Do you know if ECIES encryption time is linear with the plaintext size, using the same key length?
Nuno Lopes's user avatar
3 votes
1 answer
98 views

Is using KDF more insecure that generating key directly? (AES 256 CBC)

I am writing a PHP application that requires files to encrypted using AES-256-CBC. I have two options: Option #1 Generate a totally random AES key => User Key Generate another totally random AES ...
Mathew Paret's user avatar
1 vote
1 answer
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Can proxy re-encrypted cyphertext be identical to encrypted text by the target?

I have the following basic set-up for my question, I am getting to learn about proxy re-encryption and so far what I have looked at in more detail is this re-encryption algorithm from IronCore Labs ...
Robert Lica's user avatar
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0 answers
37 views

In the context of Hardware Security and Cryptography, how do I calculate the Algebraic Normal Form for sboxes [duplicate]

In our hardware security exercise, I am trying to calculate the ANF function manually (Sboxes) for the given table: And I came up with the result as: I thought I was calculating it correctly using ...
TorJaks669's user avatar
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1 answer
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Can a Substitution Cipher achieve Confusion and Diffusion

Can a substitution cipher achieve confusion and diffusion? By a substitution cipher I mean one where each character is replaced by another. By confusion my definition is that to solve the question, ...
revision's user avatar
2 votes
1 answer
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Is semantic security equvalent to IND-CPA?

Is semantic security equivalent to IND-CPA? If a PKE scheme like ElGamal is semantically secure, can we say it is IND-CPA? What's the relationship between semantic security and IND-CPA?
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Semantic security of ElGamal

On pages 9-11 of the paper Sequence of games, Shoup provides a detailed proof of the semantic security of a hashed EleGamal. However, he only claims security goals. I would like to know what the ...
Jeffrey's user avatar
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Is integrity guaranteed by sending plain text with public key encrypted JWT and hash?

I am currently developing an RPC system that does not require message encryption, but does need client authentication and verification of message integrity. I want the RPC server to minimize its state ...
pilaoda's user avatar
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Keccak implementation confusion

I am implementing a Keccak core in VHDL and I am currently almost done yet I am still facing some problems and would appreciate your insight. First of all I wanna ask about the padding, I know that we ...
pro orp's user avatar
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Can two different AES keys have the KCV by chance?

I am trying to check KCVs of a few keys. I am generating the KCV for the keys using the method mentioned here https://crypto.stackexchange.com/a/11873/115990 Question: Can KCVs of two different AES ...
humbleCoder's user avatar
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Lightweight length preserving encryption

I'm in need of an encryption algorithm that can be easily implemented in c, doesn't drastically increase the size of the encrypted data (the data to be encrypted will be approximately 200 bytes and ...
Hristos's user avatar
1 vote
1 answer
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What is the purpose of making salted passwords public?

So I was reading through an article about how passwords are salted and hashed through a cryptographic function here, and found out that hashed passwords, along with the plaintext salt values are ...
mantot123's user avatar
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Vulnerabilities of a word-level substitution cipher

What kind of attacks would be possible against this kind of substitution cipher? Every word in the plaintext is to be replaced with a random string of the same length The encryption of any given word ...
u2892's user avatar
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CRYSTAL-KYBER for Cloud-native storage [duplicate]

I'm trying to use CRYSTAL-KYBER encryption to protect Cloud-native storage against both normal and quantum attacks. I've read Cloud-native-security-whitepaper and found out that ...
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Security of RSW96 Timelock puzzles

I am looking to implement Time lock puzzles in a toy project I'm working on. I found this very elegant paper from Rivest et at. describing a technique for time lock puzzles. I'm wondering if the ...
enricobottazzi's user avatar
3 votes
1 answer
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Confusion in the security level offered by KYBER

I was looking at security level offered by KYBER. I have attached the table for the reference. I am little bit confused regarding the security level offered by KYBER. By definition, Level 1 in the ...
VIKAS SRIVASTAVA's user avatar
1 vote
2 answers
542 views

The future of cryptanalysis

I am an undergraduate (grade three). I am confused about the cryptanalysis. Because a lot people say that the modern ciphers are complete and they can't be cracked. Maybe the prospects for ...
Arthur Alexander's user avatar
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0 answers
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Why record signing in Rekor when using private key?

Intro When using cosign for keyless signing, the flow that happens is as such: The user runs cosign sign to sign an artifact Cosign redirects the user for a OpenID ...
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Are there any strong or well established commutative encryption algorithms?

I am looking for an encryption algorithm that's secure and commutative. This means that if N parties encrypt their data in any order, it could be decrypted in any other order.
Moaz Fathy's user avatar
2 votes
1 answer
100 views

Using AES-CBC with a random number plus a counter for the IV

I understand that AES-CBC uses the following scheme for encrypting data (diagram from Wikipedia): And, I understand that we don't want initialization vectors to be predictable or constant, and also ...
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In Vigenère, if I encrypt a plaintext with a block cipher before applying the key, will it be possible to recover the key if it repeats?

This question may seem related to this one, but it is not the same. Let's suppose I take 1GiB of data, encrypt the data with a (secure) block cipher and apply the Vigenère key, being the key much ...
alpominth's user avatar
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1 answer
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Is concatenation of secure encryptions secure?

If I have $n$ secure assymetric encryption schemes, is their concatenation $Enc_{k_1,...,k_n}(m)=Enc_{k_1}(m)||...||Enc_{k_n}(m)$ secure? My intuition is that the concatenation is secure, but I can't ...
Amit Keinan's user avatar
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0 answers
52 views

Is there a square matrix with applications in Cryptography such that the determinant of this matrix is 0 and all its sub minors are non-singular?

I am looking for a square matrix whose determinant is 0, however, all sub-minors of this matrix are non singular. This matrix needs to have applications in Cryptography. The matrix may be over any ...
Kurious Koder's user avatar
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ChaCha20 1Gb encryption speed question

I wrote a simple implementation of ChaCha20 encryptor for files in C using MbedTLS implementation. The process of encryption is standard - I set key, then for each block of fixed size I generate new ...
Enty AV's user avatar
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3 answers
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Is it possible to construct a (pseudo-)continuous PRF or MAC?

Is it possible to construct an efficient-to-compute function $F: X \rightarrow Y$ such that Given samples $(x_1, F(x_1))...(x_n, F(x_n))$, any efficient adversary ($F$ itself is kept secret) can't ...
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HillCipher, cannot get the key, Given the plaintext and the ciphertext

I'm doing a project for my Data security course, and it's to implement the HillCipher Algorithm in C#.I've successfully Implemented the Encryption and Decryption. however there is one function missing ...
Mark Maher's user avatar
4 votes
1 answer
322 views

How can I understand the gap between CPA and CCA1?

I have read lots of books about CPA,CCA1,CCA2. I understand how to get an example satisfies CPA but not CCA2. However, I can't find such a scheme which is CPA but not CCA1. What is the extra advantage ...
Wang Xingwang's user avatar
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in MA-ABE, what is the diference when prove a scheme is selective or static?

I have read [1]Decentralized Multi-authority ABE for NC1 from BDH, [2]Decentralizing Attribute-Based Encryption, [3]Fully Adaptive Decentralized Multi-Authority ABE, When I compare security proof in [...
Wang Xingwang's user avatar
4 votes
1 answer
111 views

Is there any cryptography-based assured data deletion technique currently as a standard?

I've recently read part of a book exploring secure data deletion techniques for many storage mediums. In particular, I read about assured data deletion techniques developed for data outsourced to the ...
Aljndrop's user avatar
3 votes
1 answer
721 views

Is AES a group?

The question I'm wondering is whether the AES cipher is a closed cipher (which is equivalent to AES being a group). And this question interests me due to the lack of understanding of whether it is ...
Ss1996's user avatar
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What do we mean when we say we need more than polynomial time many cipher texts

What does it mean when we say something like „we need more than polynomial time many cipher texts“? I understand it as „an adversarial can run for polynomial time and try as many messages as possible ...
jilgolfo's user avatar
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0 answers
33 views

Is it possible for a given plaintext and ciphertext to have two different keys? [duplicate]

This has probably been asked before but for a given ciphertext and plaintext pair, is it possible to have two different keys producing said pair? Or there are no collisions in AES, unlike hashing ...
user2338802's user avatar
0 votes
1 answer
215 views

Prove RSA scheme is insecure [closed]

Im reviewing my crypto and I would like to prove the following: RSA experiment where the adversary is given N, e, and y. The adversary knows p, q. I know the RSA scheme is built on the idea that it is ...
Ahmed Zaidan's user avatar
3 votes
1 answer
183 views

equivalence between entropic perfect secrecy and single probability

i'm new to information theory. I know the standard perfect secrecy definition: $$ P(M=m|C=c) = P(M=m) , $$ for all $m$ and $c$, respectively the message and the cypher. Now, i can use the entropic ...
forgetfuled's user avatar
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0 answers
40 views

Security of using predefined shares in Shamir's Secret Sharing

This is related to Is it possible to create a mix of predefined and generated shares for Shamir's Secret Sharing?, but I have unfortunately lost access to that question and can't merge accounts ...
euandeas's user avatar
0 votes
0 answers
35 views

Why is firmware implementation not preferred for more lfsr based encryption schemes?

Given that an algorithmic implementation of a linear feedback shift register based encryption scheme is (much?) more secure against side channel attacks; why are hardware platforms usually used? I get ...
Me2's user avatar
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0 votes
0 answers
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Can we be certain that Signal doesn't log metadata (e.g. message graphs)?

I know Signal uses public/private key E2E encryption to ensure it's impossible for them to read the contents of messages. WhatsApp does too, hence Signal's main attraction is that it additionally ...
Seán Healy's user avatar
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1 answer
98 views

Do I need to use unique IVs if all encrypted data is unique?

I am designing a service where each user has both a unique 256-bit private and public ID. These IDs should be derivable from one another, but only within the backend of my service (as to not expose ...
Ryan Hilbert's user avatar
1 vote
0 answers
68 views

Encryption + EUF-CMA => SUF-CMA

Does there exist a proof (paper reference welcome) that if a signature scheme is EUF-CMA, and the signatures are always encrypted, then the resulting signature scheme is SUF-CMA? That is: let SIG be ...
Mario's user avatar
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10 votes
3 answers
2k views

What are advantages of chaos based image encryption methods over simply treating images as opaque bit strings?

For an exercise at uni I am tasked with optimizing the execution speed a chaos based image encryption algorithm 1. While I have taken an introductory class to information security, I never came ...
förschter's user avatar
2 votes
2 answers
353 views

Is it possible to create a mix of predefined and generated shares for Shamir's Secret Sharing?

In standard Shamir's Secret Sharing schemes the shares are generated from randomly generated polynomials. I was wandering if it would be possible to create some predefined shares that a user would be ...
euandeas's user avatar
0 votes
1 answer
41 views

Devising a system that allows for aggregate computations but does not hold the single values

First of all apologies if this is not the right place. I am not very knowledgeable in cryptography but I thought you can at least point me in the right direction of research. The following is a toy ...
Gianpiero Cea's user avatar
2 votes
4 answers
187 views

Are there asymmetric encryption algorithms that preserve equality? Are they safe to use for data obfuscation?

I have a database table that needs to be shared between multiple parties. There is a sensitive column than must be obfuscated in a way that preserves equality relationships between records. A trusted ...
Erp12's user avatar
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3 votes
0 answers
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Does the following variant of functional encryption exist?

For a (possibly complicated) function $f: X \rightarrow Y$, can we design a set of encryption scheme $Enc, Func\_Enc$ such that, for $\forall x \in X$, $$Func\_Enc(f) = g \text{ where } g \text{ is ...
Marc_12's user avatar
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