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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symmetric-key cryptosystem or a public key cryptosystem [closed]

Consider the encryption scheme, where Alice chooses key $ K=(p, q) $ where $ p $ and $ q $ are primes and encrypts m using $ E_k(m) = (m + r_1p, m + r_2q) $ after choosing random number $ r_1 $ and $ ...
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How to create an EC point from a plaintext message for encryption

It seems that ElGamal encryption is also possible for Elliptic Curve cryptography. However, that requires the user to convert the message to a point on the curve. What strategies are there to derive a ...
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Checking availability of Unlimited Strength cryptography programatically [closed]

Is there a way in Java that I can check that the Java Virtual Machine's Cryptography Extension allows the maximum strength of cryptography to be used in the machine's jurisdiction?
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how to solve discrete logarithm problem information requested

I have seen your example about ecdlp solver :The Problem is as follows: $$E\backslash GF(p):y^2=x^3+17230x+22699$$ where $p=23981$, point $G$ with prime order $|G| = 109$ Alice creates a public key ...
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Theoretically, what if I were to change some magic numbers in, say, AES?

Purely theoretically. I know it's a bad idea to try to invent your own encryption and that's not the intention here. Just a thought experiment. Say, I change some or all of the magic numbers used in, ...
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CTF RSA Problem [closed]

I am doing a CTF and I came across a challenge I do not know how to solve. We are given a key generator and asked to find a way to factor the keys $N = pq$ it generates. The intended way is to ...
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Mac then Encrypt over Encrypt then MAC [duplicate]

Are there advantages between using Mac then Encrypt over Encrypt then MAC?
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How is the keystream actually generated in AES CTR

I've been trying to find out how the keystream in AES-CTR is generated, but I can't actually figure it out. Wikipedia and any other sites that "explain" it just say the nonce is padded with the ...
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Error propagation in CBC [duplicate]

I am doing an error propagation experiment with the CBC mode.I have encrypted a 100 byte text file with openssl. I made the 55th bytes of my encrypted file corrupted.As per theory the corresponding ...
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openssl encryption salt length

when i was reading the latest source code of openssl, i found openssl enc has an 8-byte (64-bit) salt length; because the same ...
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AES CTR - Pause and resume encryption?

I am using AES/CTR/NoPadding to encrypt while downloading files in one of my application. The encryption is done along with downloading. When the internet is not available in the middle of downloading,...
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1answer
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Is there a type of asymmetric and symmetric encryption that's fairly easy to crack?

I'm looking for a type of asymmetric and symmetric encryption that I can crack fairly easily for a school project. I'm looking to compare the difference between asymmetric and symmetric encryption. I ...
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Does encrypting the key with itself make it easier to crack the ciphertext? [duplicate]

As the title states; Is there any risk from encrypting the key with itself? EG. $C = AES(K=K, M=K)$ I'd assume not; after all, how does having the key for a safe inside the safe make it easier to ...
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CRYPTO WITHOUT THE KEY [closed]

"Y ipkywurfb zkl ckth pjf ofb bfrpkypi hf. Y jifkc iifzzy tc xymw bfemfi pjf fpywgpktcwg trb lbyr. Pjf ztwagrimtwi dfkf tc y amtrfwzf fromkkfp pt ofjtrb. Fafklpjmwu dyi wtmigcwtz. fD pjktwufb ktgwb ...
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Randomizable encryption scheme [duplicate]

Given an encryption $c$, I want to re-randomize it in such a way that the result is a ciphertext $c'$, which encrypts the same value as $c$, however it looks completely different. In a sense, the ...
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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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Is there a way to do anonymous encryption to a recipient?

Is there a way to do anonymous encryption to a recipient's Public key, where the only way to open a message would be to decrypt with your own private key + passphrase?
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Is there asymmetric encryption in SSH?

I've read in DigitalOcean article about SSH that in order for a server to authenticate a client: The server sends the client this encrypted message. If the client actually has the associated ...
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1answer
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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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How strong is XOR encryption of 256 bit plain text with 256 bit key?

I was wondering if we take just 256 bits of plain text and simply XOR every bit with a 256 bit key, how strong can it be ?
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How to do cryptography without knowing computer science or AI?

I'm interested in ciphers, codes, patterns, and mathematics, but do not have extensive computer programming acumen (VERY basic Java skills). I know nothing about machine learning, AI or anything in ...
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1answer
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Encrypt data. Create 5 keys. Just 3 keys are needed for decryption

I would like to encrypt some data and create 5 keys. These keys are stored in different places. If I want to decrypt the data I just need 3 of these 5 keys. Is there a way to do this?
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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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Why does decryption fail after modification of the ciphertext for RSA with OAEP padding

I have ciphertext which was encrypted using RSA with "OAEPWithMD5AndMGF1Padding" - i.e. OAEP using MD5 for the Mask Generation Function. I understand the general ...
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1answer
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What is the difference between PKCS1 v1.5 and PKCS7? Is PKCS7 a superset of specifications in PKCS1 1.5?

I have a requirement wherein we have to verify the PE binaries generated for an aarch64 platform. These binaries are then signed using the opensource sbsign tool ...
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True asymmetric ciphers beside RSA

Is there any TRUE public key cipher beside RSA? Most people would answer Elgamal or ECC, but for what is my understanding (and I know cryptography only superficially), those are not true asymmetric ...
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Books about stream ciphers

I am new to ciphers and for my assignment i have to implement a stream cipher algorithm without libraries (on my own). So my question is: Does anyone know about any GOOD books which have examples and ...
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Are there any web puzzles I can solve without programming knowledge?

I don't know much about computer programming (taking an Intro to Computer Programming course at school), but discovered Cicada 3301 and was hoping there is something similar I might pursue for my own ...
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2DES and 3DES against a DES build with complimentary

I saw this complicated question and I am not really sure about it, would appreciate your view on it. Is the following build stronger than 2DES or 3DES with 2 different keys (or even normal DES)? $...
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Why use PBKDF2 over SHA-512 to derive AES encryption key? [duplicate]

Suppose I am using user passwords to derive AES-128-CBC encryption key. This key will be used to encrypt some sensitive data for the user so that even the website owner / operator can not decrypt it. ...
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Simple block cipher

I came up with this concept, which I thought would be pretty secure. So the idea is this, you have a message $M$, which you split up in blocks of each 256 bits. You generate a random (pseudo-random ...
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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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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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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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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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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 a keyed MAC sufficient for integrity protection?

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