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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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Encrypted hash vs hashed encryption

Problem Is there any combination of hash and encryption algorithms with show the following properties: File $\rightarrow$ Hash $\rightarrow$ Encrypt $==$ Hash $\leftarrow$ Encrypt $\leftarrow$ File ...
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1answer
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How to multiply two Public Keys in Elliptic Curve in Go

I am working on a messaging client similar to Signal. I am stuck on implementing Tripartite Diffie-Hellman handshake in which three DH exchanges are combined to authenticate both parties and produce ...
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I don't want to store passwords, can I use them as an encryption key for another field?

I'm not a 'cryptographic' anything, so if this is a super-dumb question please let me know (politely). So here's the deal, say I don't want to store passwords because that opens me up to all sorts of ...
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Comparison between Paillier Homomophic Encryption and Public key Encryption with equality test (searchable encryption)) [on hold]

I am writing a paper where i am replacing C Paillier Homomophic Encryption and Public key Encryption with equality test (searchable encryption)). So i need to compare
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With randomized encryption, ciphertexts must be slightly longer than plaintexts in order to allow for more than one possible ciphertext per plaintext

Can anyone give me a simple example of this? "For example, if there are $2^{64}$ possible cipher texts per plain text, cipher texts must be at least 64 bits longer than plain texts" This is ...
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Decode location of an RSA encryption message [closed]

You have intercepted an RSA encrypted message with encoding exponent 7221 and base 5829679010047531. Decode the location: 815427339135043, 5556391338134431, 2892812128428033. I have to find the ...
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Part of a challenge, from a group of adults, who break ciphers [closed]

I am part of a group of adults, a cipher club who like to decode random ciphers, from texts to symbols and other things. We were presented with a set of 5 ciphered text, and we have managed to crack 3 ...
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2answers
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Mathematical explaination of file encryption for multiple persons with multiple keys

Let's say I want to encrypt a document which only can be read by John, Mike, and Dave. This can easily done with PGP/GPG: Import John‘s, Mike‘s, and Dave's public key Encrypt the document using those ...
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I2P Tunnel Creation Build on Request Record Question en(de)cryption method

Not sure if anyone here can help, but if so, sure would appreciate the help. If we read the https://geti2p.net/spec/tunnel-creation documentation page on how I2P creates a tunnel, we can read on the ...
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1answer
65 views

RSA-OAEP Padding scheme

Honestly I'm really confused about padding in RSA scheme. I don't study computer science, and I'm a beginner learning cryptography (self-taught). Can anyone give me suggestions?
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What is this called: encrypt $X$ with key $E$, decrypt $X$ with key $D$?

I am a software developer interested in developing an application with cryptography. I can explain what I want to accomplish, but I do not know the technical terms for the cryptographic functions I am ...
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transposition cipher help to solve please thank you [closed]

"hhxbv vgtkc svnxw uubba mmfay rierq oathh xebbm vkwbi qqkwk tdykq kltgx kojbx vobqv gklkz hfdau mfxso zevou nvsbz gazgy mgkch kthkc zyjfn fzljh fxsic cvkib cv" not sure if it is transposition but i ...
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How do I revoke aws smtp oauth token2 on iPhone [closed]

How do I revoke oauth 2 tokens and phishing emails
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What is the difference between Google's API-Key, OAuth Client ID and AWS Secure Token Service

What is the difference between Google's API-Key, OAuth Client ID and AWS Secure Token Service? Are they are all just providing delegation tokens, except they are from different companies? Is there a ...
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Information theoretic secure encryption based on Quantum Key distribution [closed]

Although it seems like a wildly adopted assumption that composing the One-time pad and QKD is secure, Maurer and Renner showed that this composition is not secure in the general sense. Indeed if the ...
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Type of Encryption Given The Ciphertext [closed]

I am trying to decode a ciphertext that composes of numbers and letters with a length of 56 bits, where the last three characters are ===. I'm not sure which type ...
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1answer
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Meaning of the $m$ power of a modular world

A cryptosystem is defined by a 5 tuple $(P,C,K,E,D)$=(plain text, cipher text, key, encryption function, decryption function) So, my question is with the definition given for permutation cipher, ...
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Does an encryption algorithm exist where encrypted data can be decrypted by multiple private keys?

Suppose I have Company1 with their own Public/Private Key Pairs and another Company2 with their public/private key pairs and yet ...
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0answers
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How to create an ultra-secure connection between two clients with xor? [closed]

At work, I was asked to create ultra-secure connection over lan between two computers. It will be some kind of messager. I have a bunch of same random data in them(near 100mb). Also I can start a ...
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How sensitive is Tiny Encryption Algorithm (TEA) to the magic numbers?

If I needed to implement an encryption algorithm from memory, chances are I would try to implement: TEA https://en.wikipedia.org/wiki/Tiny_Encryption_Algorithm How sensitive is it to the magic ...
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1answer
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Random letter swap soloution

I am working on a way to decipher some text generated by a small piece of code (see below). This piece of code swaps letters in the sentence at random and was wondering if there where any techniques ...
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2answers
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Using Diffie-Hellman secret key to encrypt/decrypt data?

My end goal is to encrypt data with AES-128, send it to other process and decrypt it there. While using DH key exchange protocol. I have used DH to generate a 256 bytes shared secret, but I can't use ...
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Python 3.x Cryptography Fernet / AES256 Is this safe and secure? [migrated]

I wrote this code to make easy use of the Python library Cryptography https://cryptography.io/en/latest/ to encrypt data Is this safe and secure given the user inputs a strong password? ...
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1answer
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LWE: does using only a small subspace of the plaintext space influence the security of the encryption scheme?

Regarding LWE schemes where the encryption is performed this way: for $m \in \mathbb{Z}_t$, compute $c = LWE_{\mathbf{s}}^{t/q}(m) = \{ \mathbf{a}, \mathbf{a \cdot s} + m\cdot q/t + e\} \in \mathbb{Z}...
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Calculating the inverse for a Rijndael s-box [duplicate]

I want to calculate a Rijndael S-box but something went wrong. How can I calculate the inverse? In the following is my approach: given: $f(x)=x^8+x^4+x^3+x+1 \rightarrow$ binary: 100011011 0x12 = ...
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1answer
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Does it matter if IV is used as the first block of data before the encryption and then some fixed value is used for the actual IV? [duplicate]

Usually the IV for the crypto operations is chosen randomly and is sent together with the encrypted data [at the first block]. For decryption, the IV is first extracted from data and set separately in ...
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I need help understanding bit order in DES [migrated]

I'm using a variety of references to study this algorithm, among others Christof Paar's book and classes. Currently I'm working on a custom C implementation of the algorithm, and am trying to ...
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Problems in installing Charm Crypto on Raspberry Pi 3 [migrated]

I am trying to install Charm crypto library on Raspberry Pi 3, everything works fine but make and make install fails as shown in attached screenshots 2 and 3. The configuration is successful . The ...
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How to figure out this encryption? [closed]

I can provide input to an application that encrypts plaintext via an unknown algorithm, which I would like to reverse. I can obtain plaintext:ciphertext pairs, and the length of the cipher depends on ...
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1answer
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Does the AES-KW (Key Wrap Algorithm) perform authenticated encryption?

The RFC for AES-KW doesn't actually mention authentication, only integrity, where the unwrapping/decryption process should produce an identical IV of ...
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1answer
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Simple One time Pad Probability

We have a one time pad where: We have 8 bits. probability that a bit=0 is p. The key is common for all 8 bits. It can have a value of 0 or 1 with equal probability. After applying the XOR operation ...
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What is the length of ciphertext for AES encryption using C#? [migrated]

From: Can we calculate AES ciphertext length based on the length of the plaintext? I see: output_size = input_size + (16 - (input_size % 16)) But this does not seem to correspond with what I see ...
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1answer
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What information can be gleamed by using a OTP twice with the same message?

So... C0 = K0 ⊕ M and C1 = K1 ⊕ M where K0, K1 are different random numbers. What information can you discern about the K0, K1 and M, if any? Could you use K0,K1 again with another different message ...
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1answer
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Is a 2 bit one time pad just as secure as a 128 bit one time pad?

Obviously, it would be easier to stumble across the answer, but you still couldn't be sure it's correct. So it's still theoretically secure?
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Any ideas to make an Electronic Voter Machine more secure? [closed]

EVMs are not secure they say. So how can we make it more secure tham the existing one using cryptography?
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Is AES resilient to chosen plaintext with access to related keys (key expansion primitives)?

I'm interested in knowing whether a cryptosystem is broken given access to a few primitives. $\DeclareMathOperator{\KEYEXP}{KEY\_EXP}$ $\DeclareMathOperator{\E}{E}$ Suppose that you have access to an ...
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1answer
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How secure is Firestore / Google Cloud server-side encryption?

We use Firestore. On their Google help page they say it is AES encrypted. https://cloud.google.com/firestore/docs/server-side-encryption But this means in the moment a user is logging in, the data ...
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1answer
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How to find a triple of keys that maps plaintext to given cipherext using EDE

What is a practical method for for finding a triple of keys that maps a given plaintext to a given ciphertext using EDE? I think this requires something similar to a man-in-the-middle attack...
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1answer
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Find encryption algorithm knowing input, output and secret

Today on my PC I found some old backups; they contain also some pictures I encrypted years ago with a smartphone running Windows Mobile but I don't remember the application I used to cipher them. I'm ...
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1answer
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Encryption: am I doing it right?

I'm trying to get a per-user encryption key scheme off the ground and need some validation from wiser crypto pros. Consider the following procedure: User provides registration information to include ...
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2answers
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Determine if $f(x)+x_0+x_n$ is balanced

If $f(x)=x_0x_1\oplus x_1x_2\oplus\cdots\oplus x_{n-2}x_{n-1}\oplus x_{n-1}x_n\oplus L(x)$ is a balanced boolean function (which is a boolean function whose output yields as many 0s as 1s over its ...
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GCM optimisation using $M_0$ and $R$ tables - Calculation of $R$

I'm implementing GCM in C as a way to learn about it. In the paper titled as The Galois/Counter Mode of Operation (GCM) by McGrew and Viega on chapter 4.1, page 11, 12, they talk about the ...
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Errors in LLL cracking knapsack crypto

I am attempting to try some sample knapsack encryption problems and the attack on them using the LLL algorithm. I am using here and here as the guides. They both provide examples to walk through, ...
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1answer
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Why would it be risky to let Huawei build 5G networks? [closed]

I'm wondering why there is so much debate about letting Huawei build 5G networks in Europe and other countries. Shouldn't encryption which is used more and more on the web today make all communication ...
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Insecure private-key encryption

I am learning about crytography and the differences between the public and private keys encryption examples and I was wondering if it is possible to have a private key encryption scheme that is ...
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1answer
57 views

Big-O Encryption Algorithm

I am currently doing a research paper on the Blowfish encryption algorithm and one of the components that I need to include is time and space complexity. I have tried reading academic articles and ...
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3answers
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What are some real world examples where one time pad encryption is used or can be used?

I understood that One-Time Pad (OTP) encryption ensures perfect secrecy. However, I couldn't find any real-world examples where the OTP is used. Also, which are some real-world examples where it won'...
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Are encryption algorithms with fixed-point free permutations inherently flawed?

Flaw in Enigma One of the Enigma machine's flaw was the derangement (fixed-point free permutation) of the produced ciphertext, or simply put: No plaintext-letter can be enciphered to itself. See this ...
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Time-based decryption service

i am thinking about building a public crypto service, yet at the same time, I am still quite new to crypto and therefore prone to snake-oil inventions I guess. My plan is to build a website which ...
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1answer
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Definition of symmetric cipher and definition of asymmetric cipher

So I'm currently taking a cryptography class right now and my professor has told the class that she can't even define symmetric cipher for us without getting into asymmetric ciphers and the textbook ...