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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RSA OAEP: prevention of partial decryption of ciphertexts

I'm trying to understand RSA encryption (as a beginner in cryptography). go on this wiki page http://en.wikipedia.org/wiki/Optimal_asymmetric_encryption_padding scroll down to the 2 numbered points: "...
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298 views

Interactive assumptions not falsifiable?

Can someone explain why an interactive assumption is not falsifiable? Maybe I'm misunderstanding what the statement means, but isn't even a non-interactive assumption interactive, but just with a zero ...
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Opinion on my idea for storing credit cards securely

I've been thinking of ways to store credit cards securely, I thought of this: Take the users credit card info Put the card info in a standard format "Full Name/Card Num/Security Num/Expiry Date" ...
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515 views

How represent message in Menezes–Vanstone elliptic curve cryptography

I ask about represent message in Menezes–Vanstone elliptic curve cryptography I now encrypt function as follow $C_1 = (M_1 * K_1) mod\ P$ $C_2=(M2 * k_2) mod\ P$ My question is about how much the ...
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620 views

Type of cipher used where ciphertext has no discernible pattern, spaces. Type?

What type of cipher could give ciphertext where for example random ASCII chars between say F-z (symbols and numerals inclusive), but with only a few spaces? Frequency of chars shows some similarities ...
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1k views

Serpent Cipher 128bits (Example rounds on any plaintext/key)

Is there are any possibility to see trace(example) of Serpent Encryption/Decryption on concrete plaintext/key example, (not code implementation) or at least animation of steps. During reading of ...
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106 views

exchanging private key between service and iPhone app - digital signing

I need to do digital signing of my request data which will be sent to the server. My server sends distinct private keys to her clients after authentication and expects all responses to be digitally ...
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238 views

Convergent encryption has dictionary attack, but why hash function doesn't?

Convergent encryption (CE), $E_k(d)$, is a way to encrypt the data $d$, with the characteristic that the encryption key $k$ is $k=h(d)$, where $h(\cdot)$ is a cryptographic hash function. Consider a ...
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656 views

Public and Private key encryption in simple math

Can anybody show me (or point me to resource) how to generate public key and private key with simple math? Steps which can be reproduced in a simple calculator – so the message, keys all can be ...
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106 views

Modulo settings for successful encryption?

I saw this awesome video which shows how encryption works using "discrete logarithm". The example says: $3^x\mod17$. I understood that $3$ is called “generator”, because it has no "straight" root and ...
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1k views

Commutative Encryption with RSA scheme?

I wanted to know how I could manage to do what I'm going to tell you next, with the RSA encryption/decryption scheme. So Alice and Bob each have a public key $(n, e)$ and a private key $(p, q, d)$; ...
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407 views

El Gamal encryption scheme and symmetric encryption scheme

Consider the El Gamal encryption scheme, a symmetric encryption scheme (KG,E,D), and the following hybrid encryption scheme having an encryption algorithm that, on input a public key (G,q,g,h), where ...
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366 views

How we transfer 128bits cipher to a 4x4 matrix for AES input?

Why the input cipher for AES encryption, can write in 4x4 matrix with 8 bits entires, and can said is 128bits? if each cell is 8bits in binary, how we said this matrix is represent 128bits?
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411 views

Rabin code same message sent with different $N$

I use Rabin code with modulus $N$. Now assume that Alice sends me a message $m$ $(1\le m\le N)$ encoded by Rabin code. Unfortunately after Alice sent me the text I lose the information about the ...
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221 views

Can you show how that RSA does/doesn't provide anonymity?

Considering a CPA-secure version of RSA where the ciphertext is just a rundom element from $Z^*_N$. Does that meet the anonymity requirement in which an cpa adversary cannot distinguish between a ...
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105 views

What scheme will allow merging and splitting the result of a function?

I am wondering if it's possible to have a scheme as follows. Here is the scenario: we have a set of objects (e.g. strings) {O1, O2, ..., On} we have a set of users {U1, U2, ..., Um} each user asks ...
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1k views

Decrypting a message without the private key using CRT

I am given 5 different encryption modulus, $N$, each ranging from 78 to 88 numbers long. Then for the encryption exponent, each has the same which is 5. Then I am given 5 different encrypted messages, ...
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658 views

IV and Headers inside cipher text

I am a bit confused about the use of IV, and key hash. Is the key hash and IV stored inside the headers of the cipher text? Isn't it a security risk to store this header information? By key hash I ...
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76 views

Conditions for proving that a signcryption scheme is secure

If I'm able to prove that any scheme satisfies confidentiality ad unforgeability conditions, will it be a valid signcryption scheme, without explicit signature and encryption parts ?
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1k views

How compared encryption algorithm in terms of efficiency

I want to compare two cryptographic algorithms. The first algorithm is RSA, and second algorithm is ElGamal elliptic curve cryptography. Now, I’m looking for a way to compare the speed of the two ...
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180 views

ZKP: Asymmetric encryption with confidential message and known hash

I'm searching for a ZKP package that supports asymmetric encryption so I can implement the following scenario: Carol encrypts message $m$ with Alice's public key and sends the ciphertext to Alice. ...
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1answer
239 views

Symmetric Multi-Key Decryption

Is there an encryption decryption scheme in which a group of people are all given different keys, and of which each key can decrypt a file. (I’m not talking about a scenario where a file is encrypted ...
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1answer
470 views

plaintext distribution ,perfect secrecy cryptosystem

I have been trying to solve the next problem: let pi be a perfect secrecy cryptosystem with specific plaintext probability distribution. How to prove pi will have perfect secrecy for all other ...
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1answer
150 views

Getting the Encryption Function From the Decryption Function + Decryption Key + Encrypted Item

Is it mathematically possible to always be able to get the encryption algorithm used to encrypt a certain item (file, number, text, ...etc.) by knowing the decryption algorithm that will be used to ...
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22 views

Plaintext with 'T' and 'E' alphabets missing and encrypted with Vigenere Cipher

I wrote the normal code to decrypt a Vigenere cipher encrypted text without knowing the key. But that won't work for this are two of the alphabets are missing and that would mess up the frequency ...
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24 views

Creating nested messages in OpenPGP

I need to create a nested message in OpenPGP (my understanding is that the protocol itself should support it). Let's say I have Payload ("Time in Lordran is ...
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Symmetric keys for media attachments in pairwise group messaging

One way of implementing end-to-end encrypted group chats is simply to consider it as a collection of pairwise channels. For example, in a group of Alice, Bob, and Charlie, Alice will send a message by ...
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What is the best way to encrypt whole partitions with Ed448-Goldilocks?

I like crypto, but I'm a bioanalytical chemistry person by trade. I like this algorithm and was wondering if I could use it to encrypt partitions like a MBR that prompts a passphrase, like BitLocker.
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Is there a program i can use to find a hidden message in a BMP file?

I am working on a puzzle and think there is a message hidden in one of the files that is a BMP file. I am wondering if there is a program somewhere that could find it?
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28 views

Server stored, encypted messaging app

For my personal research, I have to create a messaging app, but security is only important part of application, security from MITM (man in the middle attack), at device end, and at server level. (note:...
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38 views

If we have chunk encryption for AES-Rijndael-CBC, should we hash Authenticate/tag each single chunk with a hash vs whole file?

was frustrated by which one to pick and my brain could not guess which one is better Authenticate the whole file as one with a hash vs authenticating each ciphered text. So very quickly: i have super ...
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How to extract the keyword from a mono-alphabetic substitution cipher

I am a beginner to cryptography and I have the following question. I know that to extract plaintext from a mono-alphabetic substitution cipher I can perform shifting the characters by $n$ times until ...
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51 views

Is the scytale a Block Cipher?

Can we consider the Scytale a block cipher ? If yes why ? Can you tell me ?
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47 views

Can one encrypt a series of computation?

Normally when one speaks of encryption, it refers to encrypting data. Recently, a client requested a proprietary algorithm be executed on the client-side, in public web browsers. The input data would ...
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47 views

OTP XOR two messages

I am working on a project in which we will XOR two messages basically adding them together, $C_1= (M+K)$ and $C_2= (M'+K')$ the result should look like $K\mathbin\|K'$ and $M \oplus M'$. My question ...
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Is Attribute based Encryption used to encrypt data and apply access control on data or apply access control on data only without encryption?

I want to know if i want to encrypt data by using Attribute based Encryption, it consider encryption algorithm or i need to use one of encryption algorithms e.g. AES before use Attribute based ...
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Encryption algorithms that can be used for key exchange and can be eavesdropped

Which algorithms can be used for key exchange between two wireless nodes and are not secured, meaning they can be eavesdropped?
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AES-MixColumn layer in the last round

In the "Introduction to Cryptography: With Coding Theory" by Trappe and Washington, in the chapter about AES algorithm the authors say that in the last round of the encryption algorithm the MixColumn ...
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42 views

XORing a nonce with a ciphertext vs XORing a nonce with plain text and then encrypt

Consider a situation where a symmetric key encryption (such as AES) is used to encrypt the plain text. Moreover, a nonce is used to ensure that old communication cannot be used to perform a replay ...
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22 views

Meaning of direction in EPS

In EEA (EPS Encryption Algorithm) and EIA (EPS Integrity Algorithm), what exactly does the direction (uplink/downlink) indicate? It's confusing because for both encryption and decryption of a given ...
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40 views

Combine signature with encryption

I have some embedded device for which I want to sign and encrypt firmware files. Firmware updates are generated by me and may be installed by the customer. The encryption is supposed to protect the ...
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32 views

Can Paillier Encryption has independent decryption key?

As Pailliear cryptosystem secret key $\lambda$, depends on primes $p$ and $q$. As $\lambda = \operatorname{lcm}(p-1,q-1)$. I want decryption key to independent from $p$ and $q$. It can be possible ...
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95 views

How to implement GSW13 using Helib or SEAL?

I want to implement the homomorphic encryption scheme proposed in GSW13, and make some changes to it, but seems that there is no library that has already been implemented it. Since this is a ...
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Does it make sense to try CP-ABE in a database for a individual database records?

I'm almost ready for my graduation research project, and I'm looking for an interesting crypto-related topic. I came across CP-ABE, and since I'm working in infosec it caught my attention. Will it ...
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83 views

zero knowledge proof of range and set membership

I have a large number of items with a unique serial number and a score (score isn't always unique). There is a list which contains all of the serial numbers and their respective scores. I select 3 ...
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How many AES 128-bit keys does a MIFARE PLUS tag have?

I know that the question is a bit silly but I dont know how many keys can a MIFARE PLUS tag store in it. Provided that I have a MIFARE PLUS S tag with 4k memory room and the key length is 128 bit, ...
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Off-Chain Channel With Multi Participants That Have Different View/Write Access

I'm looking to expand my blockchain ability to have off-chain channels between different participants (let's say more than 2 participants). The requirements: Only the participants of the channel ...
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37 views

how to compute Bit Independence criterion of SBOX?

I want to compute BIC's of my Sboxes, I found out some theses for that but I could not understand how to do it. Can someone help me?
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Alternate to distributing master key to every user in circle of trust

I am designing an end-to-end encrypted file storage system where only the user should be able to access their own data. The best I could come up with is a system designed around a master key that is ...
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Method for getting encryption keys from U2F key

There are a number of questions on this site about how/can you use a U2F key to encrypt something. The main problems with doing this are that U2F keys were designed for authentication, so all they can ...