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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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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How do encrypted radios perform key exchange?

I'm having difficulty finding documentation for the over-the-air protocols used by encrypted public safety radios. It seems that most systems are based on Project 25, previously known as APCO Project ...
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How to decrypt a Vigenere cipher without knowing the key? [closed]

Given a unique Vigenere cipher text, I have to write a program in python that decrypts the cipher but we aren't given the key or length of the key. How would I go about solving this problem?
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Decryption of Vignere cipher by hand using Kasiski examination

My task is to decrypt the following message, which was encrypted with a Vignere cipher of length 4: ...
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23 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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48 views

Is this correct/incorrect password for file encryption scheme secure?

I'm writing an AES file encryption program, and I'd like to put in a way to tell whether or not the user has entered the correct password without decrypting the entire file and GCM telling me the tag ...
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How does stream cipher works? [closed]

I will be grateful if someone can explain how stream cipher works using Pseudorandom generator(PRG).
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Dual system encryption:New Techniques for Dual System Encryption and Fully Secure HIBE with Short Ciphertexts

In the paper New Techniques for Dual System Encryption and Fully Secure HIBE with Short Ciphertexts from Waters and Lewko, how can the elements $R_3$ and $R'_3$ be eliminated in the decryption ...
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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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Is a larger block size less secure against a brute-force known cipertext attack?

Suppose a ciphertext $c$ was encrypted from plaintext $m$, and we know something about the form of $m$; say, for example, that $m$ is English text. We can attempt to brute-force $m$ from $c$ by ...
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In PKI, with a hash-encrypted message (first hashed, then encrypted), how is the plaintext ever retrieved?

Consider a normal PKI encryption flow - hash the plaintext, then encrypt the hash with the private key of the sender and then encrypt it with the public key of the recipient. All this is good - and I ...
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Is there any encryption system where the sender cannot prove that a specific ciphertext belongs to a specific plaintext

I'm trying to create a message-transfer system where The encrypted messages are stored in a public database. It is possible to verify who is the sender of this message. The sender cannot prove to ...
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What is the difference between Symmetric authentication systems and Symmetric encryption systems? [closed]

I know Symmetric encryption systems. Can someone explain the difference
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Create a ciphertext that decrypt to different plaintexts with different keys in RSA

(This is inspired by this question 1; have also read this question 2 but it's one-time pad) I would like to know, given two message $m_1$ and $m_2$, as well as public keys $(e,n_1)$ and $(e,n_2)$, ...
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How RSA is implemented by authentication protocols?

I am a beginner in cryptography, i recently learned about RSA algorithm : In short, my understanding for this is : Sender needs receiver's public key to encrypt the message to a cipher so that only ...
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How challenge response password recovery mechanism works with disk encryption? [migrated]

For the sole purpose of learning, I am trying to figure out how disk encryption software is able to recover password of an encrypted disk using a challenge response mechanism. Th recovery process ...
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complexity of ElGamal ECC and Menezes-Vanstone ECC? [closed]

How to compute the complexity of ElGamal ECC and Menezes-Vanstone ECC?
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State of the Twofish encryption cipher - is it broken? [closed]

Twofish was one of the finalists in the last cipher competition together with Serpent and AES, where AES won. Do you know of any cryptanalysis on Twofish and if its considered "broken" or still ...
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How hard is it to guess a 8 digit PIN?

Say that there are different live situations where you have to select own PIN numbers. Can someone say if it is possible to guess a 8 digit pin within 3 tries, given any methods or resources? Is ...
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What is the formula to calculate password entropy? [closed]

I saw in another thread: Is using 7-8 random words from all words of a language as password a good idea? These calculations: If we assume that English has 171,476 words. Then with 8 words the ...
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How safe is my method

I'm building a website. I have an API which takes 2 parameters: delete_user(user_id, hash). And there is method to evaluate hash using SHA512: ...
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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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Is there something like a secure hashmap?

TL;DR: Is there such a thing as a hashmap whose contents cannot be read unless you have the right encryption key, and where each encryption key only works for a specific key value pair? More context: ...
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PRNG next bit test

I would like to know whether a specific PRNG satisfy the next-bit test or not. will satisfying all of NIST statistical tests on PRNG guarantees passing the next-bit test? Or is there a specific ...
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Proving the right encrypted message was sent

Total amateur to crypto here but I've searched and searched and am at the extent of my knowledge. I've gone down several avenues to satisfy what I'm looking for but I'm just going to describe what I'd ...
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Double 3DES/TDES Encryption

If 3DES/TDES (officially TDEA or Triple DEA - Triple Data Encryption Algorithm) encryption is used twice, using 6 different keys K1-...
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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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Cipher comparison chart/table?

I'm more of a visual person, so a chart or table layout usually works best to help me "see". I'm just trying to locate a resource that shows me where the various ciphers fall in relation to each ...
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Niederreiter cryptosystem sources

I want to study about Niederreiter cryptosystem and I want your opinion about sources, papers, etc. I found stuff on the Internet but I want to know if there is a good source that you may know. I want ...
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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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1answer
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Recognizing and decrypting custom cipher with known plaintext and ciphertext

I've been trying to reconstruct an encryption algorithm that produces a known ciphertext from a know plaintext. I have done some analysis: the algorithm operates on single bytes a plain text can be ...
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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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attacks and defenses on multi party Diffie-Hellman protocol

I tried to create a 4 partied Diffie-Hellman implementation for 4 people using its cyclic group property. However, I am not sure regarding those 2 issues, and would appreciate if you could elaborate ...
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Is there any vulnerability in this scheme?

We want to design a symmetric encryption scheme. Note that the following things are true for our system: The plaintext P will change every time for a given user. A user will choose a password which ...
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What encryption to choose from the SSL library in python 3?

I've been researching some of the types of encryption that the python SSL library uses. Among them the best I've seen are: ECDHE-RSA-AES256-GCM-SHA384 TLSv1.2 Kx = ECDH Au = RSA Enc = AESGCM (256) ...
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1answer
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Why is the second XOR operation in OCB mode necessary?

In Rogaway's OCB mode, the offset (derived from the key) ist XOR-added twice: Once to the plaintext block, and a second time after the Encryption. I am wondering, why the second XOR operation is ...
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Multiple (RSA) public key encryption how to verify others received the same information? Non-deterministic encryption

I have an RSA system between multiple parties. Alice takes the targets (Bob and Oliver) public keys and encrypts a message using them and sends it to them. All parties know each other's public keys ...
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1answer
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Is more ECDHE or RSA currently recommended?

Lately I have seen that many websites warn us of changing RSA for ECDH, and that the latter is much better if we use its "ephemeral" form or better known as ECDHE. So is ECDHE recommended to use more ...
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How secure is XOR-CBC?

How secure would this be? To be clear, I mean replacing the block cipher encryption step in the Wikipedia diagram explaining CBC with plain old XOR? EDIT: Replace ...
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1answer
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EL Gamal Attack without a secret key

I have the following data where all the inputs are Big Integers, group size $p$, group generator $g$ public key of the receiver $y$ $c_1$ and $c_2$ Random Number as well I am trying to execute an ...
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1answer
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How to store encrypted solutions of a find location game?

I'm coding a bot on Telegram to sustain a quiz game. A group of people (authors) can upload photos of streets or particular landscapes that they have found on internet, without any description, and ...
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Crypto AES for authentication

Is it secure to use authentication strategy like this: store key in database - crypto.randomBytes(32) store IV and encrypted data in user cookies - ...
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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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The importance of randomness in the creation of a key

Why does it matter what kind of random number generation is used during key generation? E.g. this answer states ...
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1answer
48 views

Stream cipher - Many time pad

I understand the concept that when you xor the cipher texts you get the XOR messages cause the keys get XOR-ed and cancel out... This is at least the case when both the messages are of equal lengths. ...
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Is using 7-8 random words from all words of a language as password a good idea?

The Bitcoin Bip-39 dictionary has 2048 words. And a random 24 of them are pretty secure together. What if the source is bigger (all words in the language) but there are only about 7-8 words? These ...
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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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Are TCP socket connections over private wifi encrypted using WPA2 PSK? [migrated]

I recently made a very basic TCP client/server system in C++. I got the client and server running between two computers connected to my private Wi-Fi. Since a private Wi-Fi is encrypted, does that ...
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How much long the key should be to create a secure encryption with One Time Pad? [closed]

For example would a key with 15 random letters be enough to protect a 52 letters plain text?