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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Which among the following is a method of encryption where units of plain text are replaced with cipher text according to a fixed system? [closed]

Substitution Cipher DES AES All of the above Basically, I am confused between all three. Because all of them are symmetric. Yet, AES and DES are block ciphers. Any idea?
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How to break RSA when $q = e^{-1} \bmod p$?

This problem was posed during a recently ended contest. I am given a value for n and e. e = 65537. n is a 2048-bit number. p is a 1024-bit prime number. q is the modular inverse of e mod p. That's ...
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Keyless cipher proof

I answered a question on StackOverflow yesterday that was asking why the following keyless encoding/decoding scheme for 16-bit numbers worked: Encoding Note that the "shift" operation is ...
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RSA tutorial question [duplicate]

Looking at the ASU.edu tutorial on RSA encryption, they use a strange notation: $$\text{Decoding exponent:}\quad d = e^{-1}\bmod(p-1)(q-1)$$ Normally when I see any number n taken to the -1 power, I ...
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keyring encrypted with public keys

I would like to publicly store a list of public keys of recipients in a way that only the individual recipient ( who holds the private key of a that referenced public key) can see that he is ...
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How do you use a PQC Hybrid Shared Secret in Practice?

In https://tools.ietf.org/id/draft-stebila-tls-hybrid-design-03.html, they define (many other sources do too) hybrid shared key exchange as “Hybrid” key exchange, in this context, means the use of ...
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Can a user set his public key without knowing its corresponding private key? [closed]

I'm wondering if in public key infrastructure (PKI), a system user be able to set his public key without knowing its corresponding private key. Can this be done?
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What's the average time to generate IDEA pairs?

I'm trying to implement impossible differential cryptanalysis on IDEA cipher based on the Miss in the Middle Attacks on IDEA and Khufu, I've started by implementing the cryptanalysis on 3.5-Round IDEA ...
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How SSL (similar version) works?

My book suggested the following protocol to replace SSL: A lot of the terms are familiar to me from the Original SSL, like ChangeCipherSpec message which means ...
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Are there any encryption schemes where more than one key give the same encryption and decryption operations? [duplicate]

Given an encryption scheme that takes as input a key $k$ and converts it to an encryption operation $E$ via the function $M(k) = E$, is it possible that more than one $k$ can give the same $E$? For ...
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Confirmation of receipt during the fair exchange

Is there a way to confirm the delivery of an item to the recipient e.g(bank payment)? Let's say there is a trust third party in the protocol. The sender's side (honest) says that it sent the payment, ...
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Using ed22519 signature as entropy

I am developing an application in which all application state is entirely public. Each user of the application is equipped with their own ed22519 keypair, and the application can only ask users for ...
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Why does the distribution of BFV's sk use $R_2$, and what are the disadvantages of using $\chi$?

Instead of sampling $\mathbf{s},\mathbf{u} \gets \chi$, we will sample $\mathbf{s},\mathbf{u}$ from $R_2$, i.e. the norm $||\mathbf{s}||=||\mathbf{u}|| = 1$. $\cdots$. The security implications of ...
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ElGamal cryptosystem

ElGamal cryptosystem provides multiplicative homomorphic property which can also be converted to additive homomorphic property. Can we use both properties simultaneously? For example, we want to ...
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The benefit of the shared key generated from ECDH key exchange protocol [duplicate]

What the benefit of the shared key that generated from ECDH key exchange protocol? Can I use it to encrypt the message or encrypt the public key of asymmetric encryption?
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Can functional encryption encrypt and decrypt negative integers?

I want to use DCR-based functional encryption for encryption and decryption purpose. However, I'm unsure whether DCR-based functional encryption can support negative integers. Is there any ...
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Encryption algorithm where proving the decryption is equal to spoiling the key?

Is there an encryption algorithm or MAC algorithm for which NO zero-knowledge-proof exists, provably? I want people who want to prove that a ciphertext decrypts into some plaintext to have to spoil ...
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Can asymmetric encryption be used in HMAC, and still ensure the data has not been tampered with? [closed]

Suppose I want to send a message, but not privately; I want everybody to see it, even an attacker in the middle. I would do this by appending a public key to the start of the data, which could be used ...
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Problem with implementation of Enigma Machine

I'm having trouble making an implementation of Enigma Machine in VBA. My question is about implementing the rotors and their move. To be more precise, I will show below the way that I code my Enigma ...
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Is it safe to use a signed message as a private encryption key?

Can I safely use a signature as a private key for the purposes of encryption? ...
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Are Encryption, Key Exchanges and Digital Signature the application of asymmetric encryption

Reading the wikipedia entry on asymmetric cryptography, will I be wrong to conclude that there are 3 main broad category of application for asymmetric cryptography? Mainly: encryption digital ...
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Davies-Meyer mode

While reading about the Davies-Meyer mode (and other modes), I have got some doubts: What can I use as the key to the encryption $E$? Since I am generating hash of a message (not MAC), then there ...
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Make certificate and private key available only to a single app [migrated]

I want to make a smart card reader app, that sends read data to a server. In order to be certain in the integrity of the data, I want to use a client certificate to communicate with the server and I ...
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can I get individual data by paillier decryption if we send aggregated encrypted data?

suppose there are different user data for n Smart meters. we encrypt all the individual data and then add them together. After decrypting the summation, how can we retrieve the original data? We are ...
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About the complexity of a path finding attack for a path encrypted with a block cipher (like AES). How many AES calculations count as secure?

Out of $N = s^3$ total points we pick a starting point $p$ and an end point $q$ with $$p=(p_1, p_2)$$ $$q=(q_1,q_2)$$ $$p_1,q_1 \in [0,s)$$ $$p_2,q_2 \in [0,s^2)$$ We want to find a path in between ...
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The appropriate smoothness bound

My question roots from another question asked in the community since I do not have enough reputation points to comment on the answer, I was hoping I could ask it here. How was the individual asking ...
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Is there any function that calculates Frobenius Norm in palisade? (Homomorphic encryption)

As I understand, Frobenius Norm is supported under homomorphic encryption. (It’s HE compatible.) However, I cannot seem to find the corresponding function in palisade’s library and documentation. Or ...
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Does multiple encryption help?

Suppose some original material (say a text message, text.txt) is encrypted multiple times, (say using ChaCha20) each time with a different key. Suppose the output of this process is a binary (output....
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How round constants are chosen in a block cipher?

Block ciphers that are NOT LIGHTWEIGHT use relatively complex key scheduling algorithms to enhance their security and thwart some of the known cryptographic attacks. In such ciphers round constants ...
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Short description of encryption methods? [closed]

I can't seem to wrap my head around these encryption methods. I can't find a brief description for any of them. Hash then encrypt MAC then encrypt Encrypt and MAC Encrypt then MAC
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Looking for multi-party key exchange/shared secret algorithm with specific requirements

I'm looking for the ability to create a SINGLE CONSTANT shared secret amongst two or more users (a group) AND if a new user is added to such a secured group the new user should also be able to learn ...
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Security definition for IND-CPA of public key encryption

In the security game between the challenger and the adversary for the security definition of public key encryption, the challenger creates and gives the public key pk to the adversary. The adversary ...
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What E means in Diffie Hellman protocol?

I was looking for an example of protocol to verify user's identity using Diffie Hellman which works like this: client sends: $g^x$, ...
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Prove the correctness of the RSA for $GCD(m_i,n)=1$ and $GCD(m_i,n) \neq1$ [closed]

How to make a proof of the correctness of the RSA encryption and decryption formula for $GCD(m_i,n)=1$ and $GCD(m_i,n) \neq1$ where encryption is defined as $c_i = m_{i}^e$ mod n and decryption $m_i =...
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Where there is special Modulus in Microsoft Seal?

As explained in their example here, Microsoft Seal uses a special modulus that is used for all key material like relinearization key. I wanted to ask why special modulus is used?
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Does this encryption scheme have any major vulnerabilities?

Recently I asked a question of whether there is any cryptosystem that satisfies a number of properties (read the properties). Continuing to the promise I gave there, this is my attempt to construct it....
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Multi key layered encryption verification

Is it possible to take some value text like “Hello World!” And encrypt it with a random key. Then take the encrypted message and encrypt it again with another random key. And so on… Then can you write ...
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RSA Big prime picking [closed]

Is the random picking of big n-bits random numbers for primality test a time sensitive operation? If so, would an heuristic for limiting the search space (about 5-10x) without missing out on any prime ...
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Why use cyclotomic polynomials for RLWE?

This paper On Ideal Lattices and Learning with Errors Over Rings proposed RLWE which is Ring and hence efficient version of LWE problem. My question is that they considered cyclotomic polynomials for ...
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Is possible to cipher a 64bit message into a 64bit message using public key cryptography?

I'm looking for a non-invertible bijective function mapping a 64bit value into another 64bit value. I can't use a hash because it isn't bijective. Could this be done with public key cryptography ? The ...
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Ensure that ciphertext satisfies a fixed secret polynomial

Does there exist an encryption algorithm that can ensure that given an input it will generate a ciphertext in a way that will always satisfy a fixed polynomal ? I can be flexible in the input side but ...
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Sending encrypted message without public key from recipient (elgamal)

assume Bob and Alice use Elgamal encryption scheme. Alice wants to send Bob a message, but does not know Bobs public key. Is there a way for Alice to find out Bobs public key by receiving multiple ...
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What is a ciphering key?

In Hebrew language there is the term tzophen (צופן) which means cipher. There is also a term "maphtech hatzpana" (מפתח הצפנה) which means "ciphering key". What is a ciphering key? ...
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What is the difference between AES-CCM8 mode and AES-CCM mode?

I know AES-GCM and AES-CCM but what is the difference between AES-CCM8 mode and AES-CCM mode ? Is it the length of the cipher?
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Alternative to CBC mode encryption?

Given that CBC mode encryption is vulnerable to padding oracle attacks, what is the next best alternative ? a) Include a hash check in the API scheme, validate the hash and then proceed with CBC. If ...
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Simple scheme to publish data with a private key

The goal is for Alice to send an encrypted message to Bob. Neither Bob nor anyone else should be able to decode the message. Alice should be be able to decode it, when all data is shown to her. ...
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How to quantify privacy, when using homomorphic encryption?

How can you measure how secure or private the new variables are relative to the real (actual) variables. I want to compare homomorphic encryption and differential privacy in combination with machine ...
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Is PRF Xored (or multiplied) with a random number still a secure PRF?

I've know that a PRF Xored with its key is not a secure PRF. Then I wonder that what if the Xored (or multiplied) item is another random number. The formal expression is as belows: Let $F_k(x):\{0,1\}^...
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Classical vs Quantum-Safe Algorithms and Protocols / Application Approach

Various proposals are being explored for X509 V3 certificates in a Post Quantum Cryptography (PQC) world. Currently, these include just having a certificate for classical and PQ, having a hybrid ...
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A CERTIFIED DIGITAL SIGNATURE paper pg 20 - 25

Reference paper: "A CERTIFIED DIGITAL SIGNATURE" With reference to the image above which is from Page 20 of the attached paper. What is this new protocol that the paper speaks of here? What ...
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