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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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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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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Synchronized random number generation

Let me try to reformulate the problem, as it might help a bit. The requirements are the following: At the beginning of their connection, the two end-points perform a Diffie-Hellman to derive with a ...
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How do different types of ciphers relate to each other?

I understand that there are symmetric and asymmetric (public-key) cyphers. The first have the same key used for encryption and decryption, while the second use a public key for encryption and a ...
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How $f(x)$ set in ring-lattice crypto?

I want to clear out some confusions I have about Lattice crypto. As discussed in this talk Signatures, Commitments, Zero-Knowledge, and Applications For ring $Z_q[x]/f(x)$, I want to understand ...
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What does prevent a hacker to calculate signature from message and public key without using private key? [duplicate]

I am talking about the process in the image: Everyone is saying this process is safe and and what I am claiming is impossible, but common sense says different.
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Which cipher is more secure TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA or TLS_RSA_WITH_AES_256_GCM_SHA384?

TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA supports forward secrecy but it doesn't use GCM mode and use SHA1 TLS_RSA_WITH_AES_256_GCM_SHA384 uses GCM mode and SHA2 but it doesn't support forward secrecy. ...
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What would be the consequences of using a IV smaller than the block size in CBC encryption?

Here I use a Threefish kernel module with CBC mode. But there is no hash function that can supply a IV with Threefish block size (1024-bits), so I use a 64-bit random IV inserted in the dm-crypt with ...
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Questions on "A CERTIFIED DIGITAL SIGNATURE" Pg. 19

Referenced paper here. The above excerpt is from Page 19 of attached paper. I have a few questions. y = F^9(x) is equivalent of F(F(F(F(F(F(F(F(F(x))))))))) ? The excerpt says that this allows us to ...
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Relation between oblivious linear function evaluation(OLE) can be used to build a PSI protocol

I read somewhere that oblivious linear function evaluation(OLE) can be used to build a PSI protocol. Is there any link between these two primitives?
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Close to hexa ciphers [closed]

Basically this post was about a cipher with a trailing "=" Any idea is welcome :)
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Cryptography based on #P-complete problems

Are there any examples of a cryptographic scheme based on (an average-case form of) a #P-complete problem?
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Schnorr signature | Schnorr Public Parameters

hello guys hope you are doing well :), i am trying to simulate the Schnorr Signature, but i have encountered some difficulties finding the generator, i have chosen a prime P of 1024bit and took a ...
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RSA: Obtain private key exploiting badly generated public key

I have to solve the following problem: What I have: $n$, a 2048 bit number What I need to find: $p$ and $q$ such that $n = p\cdot q$. What I know: With $p_1$ the first half of $p$ and $p_2$ the ...
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Online/offline times of Key Distribution Center and Certification Authority

In comparing the merits of a Key Distribution Center or KDC versus a single root certificate authority public key infrastructure or PKI, is it possible for the KDC to be online at all times whereas ...
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Discrete Logarithm Based algorithm

The private (secret) key in DL (discrete logarithm) based algorithms is uniformly selected from the group Zq*. This private key is then used to compute the public key. Could the opposite be done, for ...
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Secretly compute multiplication of two numbers owned by two people

For example, Alice and Bob have two numbers $a$ and $b$, respectively. They want to calculate the multiplication $a\cdot b$ without Alice knowing $b$ or Bob knowing $a$ and send this multiplication $a\...
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