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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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Upgrade to BouncyCastle 1.76 causing "CMSException: exception unwrapping key: cannot initialise algorithm parameters"

Upgrade to BouncyCastle 1.76 causing "CMSException: exception unwrapping key: cannot initialise algorithm parameters: LunaIvParameters: Unsupported engineInit method" error in RSAES-OAEP ...
user118092's user avatar
3 votes
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Is ElGamal homomorphic encryption using additive groups works only for Discrete Log ElGamal? What about EC ElGamal?

It is known that in Discrete Log ElGamal encryption, the ciphertext $E$ is encrypted as: $a\ =\ g^k$, where $k$ - random scalar from $[0,\ p)$, $g$ - group generator $b\ =\ (Y^k*m)\mod\ p$, where $Y$ -...
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Implementing password recovery in my app

I have an Android App that stores encrypted data using a key derived from user entered password (PBKDF2). If any user forgets their password, they loose access to all their data. Hence, I am trying to ...
Shahid Thaika's user avatar
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Proof of Decryption in a Chinese Remainder Theorem-Based Encryption Scheme

I've been studying a cryptographic scheme that uses the Chinese Remainder Theorem (CRT) for decryption. Here's a brief overview of the encryption and decryption process: Setup: Alice chooses two ...
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Is it possible to abstract an ElGamal encryption for EC and Discrete Log by using a Group Law?

ElGamal encryption for Discrete Log is defined as: Bob side does: $Y\ =\ (g^x)\ mod\ P$, where $g$ - generator, $x$ - random value among the group elements and $P$ - prime number, typically ultra ...
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Is a salt necessary when using a key and an intialization vector during encryption?

I use OpenSSL to encrypt passwords. For that the parameters - $S $ salt, $K$ key, $IV$ initialization vector are used. Although the command produces the results, I am not sure if the salt is really ...
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lattice RLWE encryption and decryption process

I am here trying to solve an issue that I face a lot during solving RLWE. The issue is that I am not able to retrieve the original message after the decryption process. I use the following encryption ...
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Cryptography elements requested for a plot in a story

experts. I am working on a story that involves a terabyte portable drive that has been encrypted by Person 1 and needs to be decrypted by Person 2 (Person 1 is deceased by that point). Person 1 and ...
Fritz loebl's user avatar
5 votes
4 answers
989 views

Encrypting a message by calculating the digits of a complicated irrational number

I have no background in cryptography at all so excuse my ignorance if this is a silly question. I was pondering ways in which I could encrypt a message and I came up with the following idea: Me and ...
Cristof012's user avatar
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Zero-Knowledge Proof of a number being generated "randomly" (similar to a dice roll)

If party1 asks other parties to give a random number, for simplicity, say in a range from 1 to 6 (like in a dice). Is it possible for party1 to ensure that the number received is in a given range and ...
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2 answers
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Definition of non-interactive non-commiting encryption

I'm having trouble understanding the definition of non-interactive non-committing encryption (NINCE) from the paper Separating Random Oracle Proofs from Complexity Theoretic Proofs: The Non-committing ...
Mahesh S R's user avatar
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Mental Poker: Can the shuffle of the deck be done Publicaly by a single player at the start of the game

Ref: Mental Poker Revisited by Barnett and Smart. I am looking at mental poker problem. Generally, the shuffling process is done by a single player who starts the game and not by all players. But, in ...
user60588's user avatar
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Best way of using AES GCM with static key PBKDF2/HKDF

Refering to this thread : using different IV and SALT with AES-CBC but same KEY I am in a similar situation to the one exposed, namely that I need to use AES to encrypt data, however, I cannot ...
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Is the CFB mode of Encryption related-key secure

I am going through the paper https://www.iacr.org/archive/fse2013/84240283/84240283.pdf where the related key security of CBC mode of encryption is well analyzed. I am concerned about whether the CFB ...
Crypto_Lover's user avatar
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Google Chrome displays formulas in Latex wrongly on stackexchange, why? [migrated]

Some formulas in Latex are displayed as boxes like here: Link: Statistical closeness implies computational indistinguishability I don't have this problem with Firefox or Safari. I also tried to turn ...
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Parallel block cipher in CTR mode and variable number of threads: how to deal with internal state and permit decryption?

I'm implementing a parallel block cipher (Morus, to be precise) in CTR mode and I'd like to make it flexible with respect to the number of threads. It is not difficult per se, as I can partition the ...
biagiop1986's user avatar
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1 answer
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Could this method allow two people using weak cryptography to bootstrap their way to unbreakable cryptography (e.g. otp)

Encryption schemes are usually explained to the general public in terms of "time required to break" where strong encryption like AES-256 should in theory take millions of years. Given that ...
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2 votes
1 answer
90 views

Why is the ciphertext output 32 bytes long when i encrypt a 16 bytes long plaintext by using AES-128-CBC

I am studying AES algorithm, as far as I know, encrypting a 16 bytes plaintext will result in a 16 bytes ciphertext. But I got a different result when trying to encrypt a 16 bytes plaintext using AES-...
user25513320's user avatar
1 vote
1 answer
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Can the RSA public key be used for both encryption and decryption?

My understanding of RSA Cryptography is that the Public Key is used for data encryption and Private Key is used for data decryption. But on this website(https://www.devglan.com/online-tools/rsa-...
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Division ciphertext in SEAL BFV

I am building a Logistic Regression model over encrypted data. Based on my references. I need to scale like that to apply the approximate sigmoid function in the BFV scheme However, I don't know how ...
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How is the IV/Nonce determined in OFB mode? - SQLite Encryption Extension (SEE)

I am doing some research in different methods of encryption for SQLite databases. One of the databases I have is AES-256 OFB encrypted with SEE (https://sqlite.org/see/doc/release/www/readme.wiki). ...
ritikix2006's user avatar
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How to hide a sequence number in the messages that exposed to the public?

Here is the situation: Alice sends msg1, msg2 and msg3 to Bob. Such messages are not always delivered to Bob following the same order. Bob needs to use key1 to decrypt msg1, use key2 to decrypt msg2, ...
DingoStiglitz's user avatar
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Mask-Shuffle in Mental Poker Revisited from Barnett and Smart

I am going through the paper "Mental Poker Revisited" by Barnett and Smart. I understood Section 5 in which the author explains Chaum-Pedersen (CP) protocol and how it is used in methods ...
user60588's user avatar
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Are there a cipher function $E_k$ and a hash function $H$ commutative on composition (permutable)?

Two functions $f(x)$ and $g(x)$ are commutative on composition, or permutable, if $f(g(x))=g(f(x))$. Given a file $f$, is there a cipher function $E_k$ and a hash function $H$ with the property: $H(...
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Getting the slope of a public key given its x and y coordinates

Is it possible to get the slope of a public key given its $x$ and $y$ coordinates? Since all the ECC calculations come from geometry, I thought this calculation might be possible.
Dev Tenji's user avatar
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1 answer
78 views

"Appendable" encryption scheme

Are there any encryption schemes that could be classified as "appendable"? By appendable I mean being able to add new data to the end of already encrypted data, without needing to decrypt ...
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Test data for AES based F8 encryption, F9 authentication

I am working on implementation of F8 confidentiality scheme for encryption/decryption and F9 based authentication scheme. These are specified by 3GPP standard, but the implementation in standard is ...
Ashish's user avatar
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3 answers
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Why not flip random bits of the encrypted message for additional security? (hybrid system)

Suppose a binary word of $n$ bits is the result of encryption (doesn't matter with what algorithm) that now has to be sent from person A to person B. Suppose additionally, A and B have a symmetric 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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1 answer
83 views

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
135 views

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
1 vote
1 answer
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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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1 answer
54 views

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
3 votes
0 answers
62 views

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
1 vote
1 answer
32 views

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
110 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
42 views

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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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
84 views

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
121 views

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?
Jeffrey's user avatar
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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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64 views

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
1 vote
1 answer
57 views

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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1 answer
70 views

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
131 views

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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1 answer
55 views

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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1 vote
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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 ...
LilLee's user avatar
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1 vote
0 answers
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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
222 views

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 ...
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