Questions tagged [decryption]

In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Only authorized parties can decipher a ciphertext back to plaintext and access the original information.

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Can two images generate a salt that can be used again to find one of the images? [closed]

Scenario: Given two images, generate a salt that can be used with one of the images to find the second image? Explanation with math: ...
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How many repetition in Ciphertext-Only-Attack?

Given the following algorithm, how many times do I need to repeat step 2&3 to complete the attack? Please note that block size and key are 128 bits. Step1: Prepare set S of size 2^k which contains ...
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RSA PADDING WITH e=3 [duplicate]

I have a ciphertext which has been padded with spaces from left the message is 31 bytes long and e = 3 how can I recover the message with python code .
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CCA Security/Decryption of PRF scheme

Let $F : \{0,1\}^n \times \{0,1\}^n \rightarrow \{0,1\}^n $ be a PRF. And let the encryption function be $Enc{_k}(m) = r\mathbin\| (F{_k}(m\bigoplus r)$ , r being a random value. Im trying to proof ...
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I do many searches but can't find any explanation about “AES analysis using entropy”

I found this scenario in CRYPTOOL2 templates but there is no explanation how entropy is used. There is just a short description "This template shows how to use a brute-force search to attack an ...
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Find IV and the key ? AES with CFB or OFB

I have a question about the AES-128 and AES-256 encryption method. I need to encrypt 64-bit size data in and out. I want to encrypt them with AES. So I turned to AES-OFB or AES-CFB because these ...
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RSA encryption/decryption values not working as expected [duplicate]

I'm faced with an issue I can't seem to understand when it comes to RSA. Below are my values for all of the parameters, unfortunately I can't seem to get the expected decrypted values from my ...
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RSA Encryption that only my family could decrypt

I was doing some thinking about what would happen to my computer and passwords if I fell off the earth tomorrow. I wanted to have a message that only they would have the ability to decrypt and I ...
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What is the exact meaning of the public key cryptosystem properties in New Directions In Cryptography by Diffie and Hellman

I'm quite new to cryptography and don't have much mathematical knowledge. I'm studying cryptography, especially public key algorithms. I have some basic knowledge of public key algorithms so I know ...
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Why does the Bombe not consider the Ringstellung when determining stecker pairs?

I am doing research on the Bombe Machine, and I read that when the Bombe tries to find the stecker (plugboard) partners of letters, it only needs to use the rotor types and arrangement and also the "...
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Why are the indicator drums of a Bombe machine labelled from A to Z clockwise?

I am researching the Bombe Machine, having just completed a project on the Enigma Machine. I visited The Rutherford Journal - The Turing Bombe, and it claimed that The scales on the three ...
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Encryption and decryption with Diffie-Hellman

I don't understand how it works. I only found explanations about the key exchange, but what about the actual encryption and decryption? Do you use the session key $K$ with a symmetric algorithm? Do ...
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When is a cryptosystem or its algorithm (like RSA) considered efficient?

When is a cryptosystem (like RSA) or its algorithm for keygeneration, encryption and decryption of messages considered efficient? Is there some bound in complexity which splits both efficient and not ...
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What type of encryption is this? [closed]

2018000010 - YjRxEBukq Encrypted O6at6Op6sGcAfLoBPhx8Xm89qWEZcw2jkmIxmqM27wAd0V1fWtuVmh9ofPX5n803Q7mnaWsWXRq2TA+1vUbj+TB62jJXNGhJPh17chGPTC3hTKVnItlpHSotwneieheRNUC0M/+zXyu8Ag8iQxP/NSFY2QO7vXwK/...
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Asymmetric Cryptography decryption

I am new to cryptography, i know essential part of asymmetric cryptography but is it possible to decrypt 617 decimal digits (2,048 bits) with RSA ? How it can be factored?
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Number of operations for Elgamal cryptosystem

In page 408 of Hoffstein, Piper, and Silverman's Introduction to Mathematical Cryptography, it says "Roughly speaking, in order to achieve $k$ bits of security, encryption and decryption for ...
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Design flaws in the round-key generation mechanism of Data Encryption Standard (DES) [duplicate]

I am beginner in Cryptography, I want to ask that what are two design flaws in the round-key generation mechanism of Data Encryption Standard (DES) that can lead to the occurrence of weak and semi-...
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Confused in selecting the encryption method for mobile number and email encryption

I'm new in cryptography and I'm developing a mobile app that gets user_name, E-mail ID, and ...
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What measures can I do to prevent decryption of encrypted data?

This is entirely hypothetical, I'm working on securing some data and I want to make sure we do this properly. If I have a list of information which is encrypted (say, using a 256 bit encryption key) ...
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Encryption & decryption in AES CBC mode - Which is faster?

I wrote a small code to compute the time consumption by the AES in CBC mode, I noticed that the encryption is faster than the decryption, my question: Is my result correct? If yes, why is the ...
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The way to break Diffie-Hellman(small nonprime number)

i am wondering how to break DH(small nonprime number). Let's say we don't know: $a$: Alice's private key $b$: Bob's private key And we know: $N$: nonprime number $p$,$q$: $N = p * q$ ($p$ and $q$...
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Does multiple substitutions increase security? [duplicate]

Yes, because the attacker must decrypt the cypher text twice No, because it is equivalent to a single substitution Maybe, depending on the complexity of each substitution
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AES 5-round Square attack, how to choose plaintexts?

I know that we need to generate a delta-set (with 256 plaintexts). During the attack, we guess 4 bytes of round 5 key and 1 bytes of round 4 key, which allows us the byte at one position of the state ...
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What is the exact algorithm for encryption and decryption with hummingbird-1 cryptography?

I have really googled the entire internet but could not find a clear algorithm for hummingbird-1 cryptography.The problem emerges in the decryption module: What is the initial value of state register ...
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Unable to determine plaintext from ciphertext

Given the letter-number cipher: a=00, b=01, c=02, etc., encrypt the word 'hi' and decrypt its ciphertext using RSA. The public key is (5,35) and the private key is (29,35). I know that 'hi' is ...
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How is asymmetric cryptography safe if one of the keys is public?

Let's suppose $A$ is sending a message $m$ to $B$ using asymmetric cryptography. To guarantee the authenticity of a message, $A$ encrypts $m$ with $A$'s private key: $E(m, k_A) = m_A$. Then, $A$ ...
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Finding IV in AES-128 having partial Key and plaintext

Let's suppose we have the plaintext, 14/16 char of the key and the first 2 and the last 36 chars of encrypted data (that is 64 char long). What I want is to find the IV. The cipher algorithm is AES (I ...
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What's a relatively fast way of checking if a string is decrypted English?

I asked this on Stack Overflow but I was told to ask here. I'm writing a program that decrypts text encrypted using a Vigenere cipher. It's been working very well so far, but my current issue is that ...
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How to decipher an ADFGVX cipher?

I got introduced to the ADFGVX cipher, and it seems very tedious to decipher such ciphertexts. If I do not have access to the key square and the keyword, and I am just given the ciphertext and a ...
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Enforce weak RSA in TLS

I'm going to give a small talk on the mathematical background of RSA. My audience will consist mostly of software engineers and to make the mathematical stuff tangible, I wanted to demonstrate how to ...
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Relationship between $N$ and $\phi(N)$ in the RSA algorithm

Recently I started learning how the RSA algorithm works and there is one single part of the computation which really confuses me and can't get over it. Let's say I chose 2 prime numbers, namely $P ...
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How to decrypt using CRT, and then verify by encrypting without CRT?

Here is the actual question that I need to answer: An RSA encryption scheme has the set-up parameters $p = 31$ and $q = 37$. The public exponent is $e = 17$. Decrypt the ciphertext $y = 2$ using the ...
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A doubt about Diffie-Hellman Key Exchange

I have a doubt about the Diffie-Hellman problem: Is it possible to send a message to someone using only the Diffie–Hellman key exchange? Since it's called a key exchange can you only make a key?
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RSA Decryption: Doubts: knowing p or $\phi(n)$ can lead to find private exponent?

I have some doubts about RSA (the public key $n$ and $e$ is public): Note $n = pq$ and $\phi (n) = (p-1)(q-1)$ 1) Say if some hacker knew $p$, why would it be easy for them to find $q, \phi (n), d$? ...
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Finding a dataset to benchmark cryptographic algorithms

I’m planning to compare cryptographic algorithms in terms of encryption/decryption time, memory used etc. and for that I’m in need of a standard dataset consisting of plaintexts of different bit sizes ...
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Three Pass Protocol Question!

Alice and Bob have agreed to use the Three Pass Protocol. p=1009 Alice chooses the encryption exponent e_A = 101 Bob chooses the encryption exponent e_B = 209 Now Alice and Bob send three ...
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How do I prove that a user encrypted the data?

I am using homomorphic encryption, and I need to check whether or not a user's data is actually encrypted. For example, an eCommerce website pulls data from a user called Alice and wants to prove to ...
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Bitslice DES decryption

I would like to implement fast DES decryption using Bitslice technique. Without bitslice DES technique, I have already done decrpytion in this source code by changing the for loop from 15 to 0. In ...
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One-Time Pad: True or False

Suppose a message $M$ was encrypted with a one-time pad. If we learned the first half of the original text is some substring $s$, would we have a better chance of cracking the rest of the message? Is ...
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How can a derived key be verified to be the right key?

Assuming I am using some derivation function to generate encryption key from the string to encrypt a file. How that string is later verified during decryption? If user enters wrong password/string, ...
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Would creating a custom human language be stronger protection than encrypting a known human language?

There are some languages that people haven't been able to read (Cretan Hieroglyphics for example). Does that mean that you can better protect data by making your own language than by encrypting an ...
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I know my passphrase. I don't remember specifically how I entered it

First if this is the wrong place to post this please forgive me. I know my passphrase. I don't remember specifically how I entered it. ex. If the phrase is "The house at the end is blue and white. I ...
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How to recover deleted-recovered windows efs-encrypted files?

I'd some EFS-encrypted files on a HDD which were deleted unintentionally. I used a data recovery software to restore them, but afterward, windows does not recognize those recovered files as encrypted ...
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Proof that Niederreiter Cryptosystem is correct

I read about Niederreiter Cryptosystem. I understood the Key Generator, encryption and decryption of the cryptosystem, but if I want to prove that is a correct cryptosystem, what should I do?
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RSA: How to compute plaintexts knowing ciphertexts, public key and relation between plaintexts

I'm trying to solve an exercise where you have to compute two plaintexts $p_1$ and $p_2$, knowing the corresponding ciphertexts $c_1$ and $c_2$ and the public key, of which $e=3$, and $n$ is a large ...
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Is direct RSA encryption of AES keys secure?

I am wondering: If we take this scheme/procedure and each of it seems very secure (to me at least), is it truly secure or is there a vulnerability hidden in the process? This is the scheme: Bob has ...
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decrypting el gamal encrypted messages in regards to k being used

i am trying to understand the differences of using k in the following scenarios to better understand the protocol and most importantly the consequences of using such k. so i wonder, some user, call ...
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My RSA decryption doesnt match answer

Break the RSA code whose key is $(n, e) = (8369428283, 1234567)$. Find the deciphering key and then decipher the message under the assumption that the plaintext consists of 7-letter blocks in the ...
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Construct another ciphertext that decrypts to same message without knowing key in Elgamal

I read about ElGamal from various resources and I was wondering if the following is true. Would appreciate if you could elaborate on it so I can understand better: Is it possible to construct, given ...