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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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150 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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38 views

Why doesn't WhatsApp encryption multiply file size [duplicate]

WhatsApp uses and end-to-end encryption, on both personal and group chats. According to my understanding, that means every message I send to a group is encrypted on my Device for every group member ...
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How to perform ByteSub transformation? [duplicate]

Can anybody please tell me how do we perform ByteSub transformation of AES to 01001001.
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25 views

How to show that Affine crypto have a valid decryption

I just need to know how to attack a question I have in my textbook this is like: Let $E_1 (x) \equiv 17x + 7 \pmod{28}$ and $E_2(x) \equiv 23x + 11 \pmod{28}$ be encryption functions for two ...
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41 views

Generate private key from public key RSA

I am doing a tutorial where my lecturer (PhD) gave me an optional question to do relating to RSA. He said: write a python function that takes as input the server’s public key and then uses that to ...
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What encryption should I use: Blowfish, Twofish, or Threefish?

The title of this thread pretty much sums up what I'm asking: what is the best encryption to use out of the three — Blowfish, Twofish, or Threefish?
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What is the likely cause the RSA algorithm gives back plain text in this case?

Text book question of Chapter 9 of "Crypto and Network Security" by William Stallings: When using the RSA Algorithm — if a small number of repeated encodings give back the plain text, what is the ...
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1answer
48 views

Is a keyed MAC sufficient for integrity protection?

I'm working with the above figure which shows a challenge-response protocol. ...
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1answer
52 views

Why do we use prime numbers apart from hard factorization?

Why are prime numbers important in cryptographic constructs? I am not interested in RSA examples where factorization is the hard problem itself, that makes sense. However wherever I go I encounter ...
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51 views

Difference between Key Scheduling and Key Generation?

I am a little bit confused in the terms i.e Key Scheduling and Key Generation. What is the actual difference between these two terms? According to Wikipedia, the terms are described as: Key ...
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24 views

What does the server do on receipt of a one-time-password?

I'm trying to understand this question and I do not understand part of it. I have part of figured out, part of it not. Considering the hash function h(i) = (i + 5) mod 7, used in an implementation ...
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Is bit encryption enough?

Assume that $\Pi$ is a secure PKE scheme (or other appropriate encryption schemes) with 1-bit message space. And it can be applied bit-by-bit to construct a many-bit encryption scheme $\Pi'$. ...
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Diffie-Hellman key exchange in four parties [on hold]

I understand the concept of 2 and 3 parties Here is the code of 3 parties ...
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26 views

What encryption / cryptography method is used here? [on hold]

I have no clue what sort of encryption is used in this piece. Does anyone has any clue? The only information I got is that the dots represents a space.
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How can frequency analysis be applied to modern ciphers?

I am building a computer program that deciphers Caesar, Vigenere and monoalphabetic substitution ciphers. All of those are susceptible to frequency analysis. However, it does not seem to be real-world ...
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26 views

I have been given a challenge to solve a string wich results in a word [on hold]

The string that i have been given is this; LKamdakW23MMDD22/23nmDlMNDwnn/ksnaw1827das82bka6/1244nfk2n3k1== I am only told that it contains a word/s When i first recieved this challenge i tried ...
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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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1answer
61 views

Can a message encrypted with one AES-256-GCM implementation always be decrypted with another?

I have a cookie being encrypted with AES-256-GCM in Rust using ring. I need to decrypt the cookie in Node.js. I'm using the standard crypto library, but it's just not working. My understanding is ...
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Is there a bulletproof way to know a file has been successfully decrypted?

I am wondering whether there is a bulletproof way to know if one is successful in decrypting a file. As an example, say I encrypt a text file and protect it with a 3 letter password. I use brute ...
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Arlo security system hack [closed]

Can anyone tell me how to see if my Arlo is being hacked through my Mac, keys, passwords, etc. m clueless but I
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55 views

Encrypted vs unencrypted digital signatures [duplicate]

Is there a difference in terms of security between An encrypted stream of bits obtained by encrypting a plaintext concatenated with it's signature $ C = E_k(plaintext||\sigma)$ where $E$ is a ...
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1k views

Proof that a hash matches an encrypted file

Assume that Alice has a file $F$ which she is going to send, in encrypted form to Bob. Alice possesses $F$ and an encryption key $K$. She sends to Bob the encryption of $F$ using $K$, $E(F,K)$ as ...
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215 views

If you receive a message with a digital signature, how do you know what verification key to use and the verification algorithm?

Really, I'm asking how do you know who sent it? My confusion has arisen from the following scenario... Problems with Signing-then-encrypting. If Alice digitally signed some data and then encrypted ...
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25 views

Rotate values in predefined manner

I want to create a Server S1, that publish a different value every 10 minutes on the internet. The value looks something like f7826da6-4fa2-4e98-8024-bc5b71e0893e. ...
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1answer
54 views

Password to password mapping

DISCLAIMER: I understand the question might be a bit amateurish due to my limited knowledge of cryptography but, please, bear with me for a minute. QUESTION: Suppose a user Alice generates a pass ...
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1answer
38 views

Is hybrid encryption required to use Attribute based Encryption to encrypt messages?

Does the mechanism behind Attribute Based Encryption require us to first encrypt the message by using a symmetric cipher, e.g. AES, and then encrypt the AES key by using Attribute Based Encryption? ...
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36 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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423 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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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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A specific way for deniable encryption

I read the summary of deniable encryption on wikipedia: https://en.wikipedia.org/wiki/Deniable_encryption Then I read a question, by doom123 on security.SE: https:/...
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Problem regarding computational indistinguishability [closed]

I've been dealing with this question for the last couple of days: Let S0 and S1 be two non-uniform PPT algorithms, and let X = {Xn}n∈N be a distribution ensemble. Assume that X,S0(X) ≈c X,S1(X) , (≈...
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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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Question about RSA timing attack and a Chosen Ciphertext Attack on RSA

I am quite new to the RSA and I have a couple of questions that confuse me. Q1: A Timing attack on RSA can be prevented _____________________________ A. By performing the “square and multiply” ...
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what exactly mean by Attribute based Encryption? [duplicate]

I want to know if Attribute based Encryption used to encrypt data or apply access control on data only without encrypting it.
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1answer
71 views

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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66 views

RSA - Calculating $d$ given $\varphi (N)$ and $N$

From this discussion, I know that if I know $\varphi (N)$ and $N$ (where $N=pq$, $p$ and $q$ prime), then I can very easily get $p$ and $q$. Suppose I have the encrypted message $c$. I want to get ...
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How does Microsoft's BitLocker Recovery Code work?

I don't trust Microsoft BitLocker because it is closed source, which makes it so people can't audit it. But now I'm really interested in how its recovery code works. In my own knowledge, encrypted ...
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2answers
256 views

If classical ciphers are used with compressed plaintext, how much does it make frequency analysis attack harder?

Classical ciphers, such as Vigenère cipher, are weak and no longer be used. They can be broken by using frequency analysis, that is a well-known fact. But, the frequency analysis often depends on the ...
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1answer
168 views

How can recovered 5-letters plain text help me to recover reused OTP key

I have 10 cipher texts ciphered with One Time Pad (OTP) using the same key. I need to recover the key (or in other words, to recover the 11th cipher text which I assumed would require me to recover ...
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1answer
92 views

Encrypt a file with AES using a secret key derived with Argon2

I would like to encrypt some sensitive files on my computer and smartphone so that they remain unreadable even if the computer is stolen. So far as I'm concerned, AES is the best encryption algorithm,...
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If you encrypt an image (AES), is it still an image and can you view it?

Can you encrypt an image (with AES) such that you can open it as a png/jpeg?
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How to encrypt small pieces of data (2 - 4 bytes) within Beacon advertising packet?

I'm developing a medical device that operates under extreme low-power constraints and transmits data with BLE, where every unnecessary millisecond of air time matters. I am developing a Beacon ...
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3answers
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Method to calculating e in RSA

For simplicity I choose two small primes for p and q. p=3 q=11 n=33 Φ(n)=20 Now we need ...
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71 views

RSA factorization [closed]

I'm trying to factor the given modulus, to find $p$ and $q$ so I can calculate the totient and then use that to decipher a message, but so far most of my attempts have fallen flat. I did notice that ...
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Efficient AES - Use of T-tables

I'm really in trouble! I'm trying to understand how the T-tables in AES encryption work. But I don't know if I get the point. What I understood is that they are used to reduce the whole computation of ...
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1answer
36 views

data migration: bcrypt to bcrypt different salts

I'm migrating passwords from one system (bcrypt) to another (also bcrypt) differing only in their salting. I noticed that encrypting the same plaintext password on one system generates a different ...
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1answer
124 views

Chacha20 internal counter/position and nonce

I have to encrypt the communications between two devices. I was planning on using a timestamp(in seconds) and the serial number as the nonce. I know its impossible for me to send more than 100 ...
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Plain text size limits for AES-GCM mode just 64GB?

Based on NIST SP 800-38D section 5.2.1.1, it seems that the maximum length of plaintext is 2^39-256 bits ~ 64 GB. We've got 100+GB files in genomics that need to be GCM encrypted so are concerned ...
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37 views

Decently safe amount of AES key derivation?

I am encrypting my computer using Veracrypt. The default 500,000 derivations is quite slow, what would a "safe" balance be between security and speed? My password is more than 20 characters.