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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why there is a need to send iv with cipher text?
From what I understand by reading TLS 1.2 RFC (key calculation), PRF is used for this with the master key to derive the IV, so both side can generate the same IV because of the nature of PRF.
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Security concerns of FF3 for in-place encryption
There have been publicized attacks that break FF3 for small domains, specifically "Breaking the FF3 Format-Preserving Encryption
Standard over Small Domains" by Durak & Vaudenay. However,...
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Algorithm to turn a blockcipher into a PRP for any (large) group size
Which algorithm is most efficient to turn a 128 bit block cipher and create a PRP for any group size, e.g. for values in a range $[0..n)$ where $n$ isn't necessarily a an exponent of two? I'm ...
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what are the security flaw of a simple Encryption algorithm made with SHA hash fonction? [duplicate]
I'm wondering what would be any major flaw of a simple Encryption algorithme based on Hash fonction like SHA:
The algorithm is:
Use SHA on a password and then keep hashing the output to concatenate a ...
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Format-Preserving Encryption with FF3 Algorithm - Minimum Length Constraints
I've built a system for format-preserving encryption (FPE) using the FF3 algorithm. The system is designed to encrypt any type of data while preserving the original format. For example, if the input ...
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Bound for Zhandry's result in Quantum random Oracle Model using the inequality of Markov brothers
In the proof of Theorem 3.2 in the paper 'Secure Identity-Based Encryption in the Quantum Random Oracle Model' by Zhandry, the author utilized the inequality by Duffin and Schaffer [DS41] (Markov ...
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An upper bound for advantage related to differential privacy
My previous question define a security game, advantage $\mathsf{Adv}$ and two probability distributions $P_{m_0}$ and $P_{m_1}$, representing $Enc_k(m_0)$ and $Enc_k(m_1)$ separately.
There, my main ...
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An upper bound for advantage in a security game
Suppose I have defined a security game in a private-key (symmetric) encryption scheme.
Remark: Note that encryption algorithm is probabilistic, so for a specific message m, $Enc_k(m)$ might output a ...
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What is the difference between public and private RSA keys? [duplicate]
I have been learning about generating RSA keys and am wondering if there is a particular reason why the private key is the private key and the public the public. As far as I know the encryption is bi-...
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virtual encryption vs non virtual? [closed]
quick question, i couple of months ago i was talking to someone over discord and they told me that veracrypt isn't very good because it was a "virtual" encryption program and that non ...
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SecureSWF Encryption
I have a problem regarding an swf file of an AS3 game. I intend to decompile the file in question, I am trying to open the file with JPEXS, but I am having some issues since the SWF file seems to be ...
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E2EE Group message encryption
I'm studying E2EE (end to end encryption) at the moment. I have come across Whatsapp white paper and watched a greatly explanatory video of TextSecure (the precursor of E2EE nowadays).
I have a ...
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Finding wifi encryption key in memory
I wanted to know whether the encryption keys derived for data encryption are stored in RAM or not after establishing a Wi-Fi connection in WPA2 and WPA3 protocols. If the answer is yes, can these keys ...
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Modifying counter sequence in CTR mode of operation to mitigate IV+Nonce near collision
The CTR mode of operation converts a block cipher into a stream cipher by having it encrypt a series of counter values (which are derived from the nonce+IV). So long as the counter values used with a ...
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Designing a Simple Custom Encryption Algorithm for Messaging: Introducing the "MessageMix Cipher" [closed]
I'm working on developing a custom encryption algorithm specifically tailored for messaging applications. The goal is to balance security, efficiency, and simplicity, so that the algorithm is ...
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What is the purpose of plaintext padding before encoding it into a elliptic curve point over a finite field in an EC ElGamal?
In EC ElGamal the encryption flow for a plaintext is well-known and clear, and for encoding a plaintext into an elliptic curve point over a finite field I use the following strategy:
Take the size of ...
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"Efficient" encryption scheme that is perfectly secret for two distinct messages
In Katz and Lindell's Introduction to Modern Cryptography, Exercise 2.19 asks to find an encryption scheme that is perfectly secret for two distinct messages*, with the following hint:
The encryption ...
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Is it possible to encrypt a message using only the recipient's Ed25519 public key?
Suppose:
Alice knows the Ed25519 public key of Bob
Bob is using his Ed25519 private key / seed in the usual way for digital signatures
Clearly, Alice can verify messages signed by Bob.
Is there any ...
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How do lattice based LWE protocols match their keys after generating them?
I am trying to implement a cryptographic protocol based on the following paper explaining the creation of the Swoosh lattice-based NIKE. They also provide a Rust and Jasmine implementation which I ...
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Issues with Point Addition to the Identity Element in Elliptic Curve Point Multiplication Over Weierstrass Curve in Projective Coordinates
I am currently implementing Elliptic Curve (EC) point multiplication over a Weierstrass curve using projective coordinates. Specifically, I am trying to add a point $P$ to the identity element (...
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Are Java PKCS #12 key stores reasonably secure with average strength passwords?
Suppose:
We are using an application that stores sensitive private key information in a standard Java PKCS #12 keystore.
Users are expected to provide an overall store password and also a password ...
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Playing safe when shortening up public key hashes
When using subtle crypto (in my case ECDSA/P-384), what exactly guarantees that a subset of the public key hash prefixed/suffixed with any symbol(s) would yield ...
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What would the cryptographic strength of 3DES-squared be?
I know that 3DES was considered to increase the strength of DES from 56-bit to 112-bit (now considered 80-bit) by using 3 DES keys and doing DES-Encrypt(DES-Decrypt(DES-Encrypt(plain-text, key1), key2)...
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Is it safer to use many encryption softwares/algorithms for encrypting a file?
I am considering that there may be two ways to have a crypto broken:
The crypto algorithm may age and become vulnerable by applying advanced cryptanalysis methods, just like what happened with old ...
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Effective bit shuffling function for DDoS protection
I'm working on some DDoS protection and I basically need to come up with a simple encryption function to encrypt the first few bytes of each packet. A firewall will decrypt those few first bytes and ...
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Deliberate error in decryption by modifying the encryption
Are you aware of any cryptosystem in which the following is doable:
The sender of information can deliberately manipulate the encryption process such that some controlled error is produced in the ...
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Security of cascaded ciphers (including question on counter-example from a paper)
A recurring theme is the security benefits of cascading two or more different ciphers. The idea is to enhance security, especially if one of the ciphers is later compromised. Intuitively (see below), ...
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About TFHE schemes
I'm starting to read about TFHE, however my background is not that deep. Mostly, I've learnt about it thanks to this paper, and I am trying to delve deeper into it. I've also read the Zama blog post ...
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What are the recommended parameters for NTRUEncrypt?
I'm looking into NTRU for the first time and I am confused by the variants and the set of parameters. I'd like to use a secure NTRU-based cryptosystem to have a (plausibly) quantum secure PKE offering ...
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How do cache-timing attacks determine the secret keys of encryption algorithms?
In cache-timing attacks like prime+probe, attacking programs are able to discover the addresses of a victim program's data in main memory. These attacks are often used to determine the secret keys ...
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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 ...
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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 ...
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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 ...
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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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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 ...
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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 ...
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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 ...
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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 ...
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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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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-...
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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). ...
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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, ...
