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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Encryption algorithm with random number generator and seed [closed]

I am an amateur working in another field, but I am interested in CS. Recently, I dabbled in cryptography. I came up with the following to encrypt text: 1: convert text to unicode bit representation ...
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Files lost by encfs [closed]

I would like to ask you for a help. I recently used the software encfs in my ubuntu 18.04 laptop. I created a new stash using the same software in my desktop. I would like to list the steps.... I ...
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Safety of encryption when knowing part of the content

I want to encrypt a JSON file while exposing its interface (the name of the object fields) in clear text. Since this exposes part of the content of the file, my guess is that an attacker could use ...
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Which is the simplest cryptographic algorithm which is close to commercial-level security?

An algorithm is simpler than another if It is easier to explain to a noob with basic high-school math knowledge. It is easier to securely self-implement by an intermediate programmer (Yes I know one ...
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Why are ed25519 keys not recommended for encryption?

Was wondering why there is no straightforward way of using ed25519 keys for encryption. Then I found this: https://github.com/indutny/elliptic/issues/108 There it is stated that it's unlike RSA not ...
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Why don't most encryption algorithms use perfect secrecy?

Isn't it possible to make algorithms that are both computationally complex and have many possible answers if you try to crack them without knowing the password? Why aren't many popular algorithms like ...
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How Secure Is This One-Way Function (Key Schedule)

While thinking about cryptography and how to "derive a key schedule" (like in AES), I thought of an algorithm that I can't figure out how to reverse (which is good). It's very simple and ...
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is it unsafe to AES encrypt using multiple modes?

Example: ...
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Is 512 bits a more secure hashing than 256 bits?

I know that 512 bit hashing is more secure, but I don't really know why. I hope someone can help me to better understand it in more detail.
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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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AES encryption for repetitive small data packets

I'm trying to implement simple AES encryption for small data packets (8bytes, fixed length) being sent from nodes with very little computational resources. Ideally the encrypted data would be a single ...
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Choosing UWP encryption algorithms

I've just come across the large variety of encryption ciphers available in the UWP WinRT API, both symmetric and asymmetric. I'm trying to figure out which are commonly seen as the most favourable ...
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openssl how to show key encryption algorithm [migrated]

When generating a key with openssl one can choose to encrypt the generated key using a password. openssl genpkey -algorithm rsa -out rsa.key -aes-128-cbc In this ...
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Are there any weak nonce-misuse resistant encryption scheme?

Nonce-misuse resistance seems to have two standard notions: The stronger notion: this reveals nothing unless the exact same nonce is used to encrypt the exact same message twice. In this case, the ...
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Multiple IV CBC

CBC's encryption is not paralelizable but I could divide a 64 block message in 4 16 block parts and encrypt those 4 parts separatly in parallel using a diferent IV for each one. Is this unsecure ? Is ...
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How to justify the lightweight symmetric PRESENT encryption algorithm is more secure?

My domain is VLSI design, currently, I'm working on PRESENT Lightweight cryptographic algorithm. I want to know how to improve the security of the algorithm rather than increasing bit size? Is there ...
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Using xor encryption in the following use case

I use an encryption scheme based on a symmetric cipher, with the corresponding symmetric key encrypted with RSA/OAEP using the public RSA key of the recipient. I now want to use ECC crypto in ...
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Can repeatedly encrypting a message with a secure cipher ever produce the original input like what happens in ROT13?

Lets say we have a message 'm'. We encrypt 'm' using a stream cipher or any other type of cipher with cryptographic security that produces an output equal in length to the length of 'm'. Then if we ...
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how to Design an AES like block cipher with block length and key length equal to 64 bits

Design an AES like block cipher with block length and key length equal to 64 bits.
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How to recover RSA messages if they are padded with spaces?

I have a message m="hunter". Let's say we pad it with 2 spaces from the left making the final message as ...
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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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Construction of a “simple”, nothing-up-my-sleeves, provably KPA resistant symmetric cipher

Why is AES secure? Apparently there is no answer - Why is AES resistant to known-plaintext attacks?. With this in mind, one would obviously want a cipher that is mathematically provable to be ...
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Learning cryptography [closed]

I am new to cryptography but I want to learn about it. I would like to get from you a list (possibly ordered) of "must have and read" book titles. Best regards
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Is there a name for strong human-computable encryption schemes? Are there definitions for “human-computable”?

Background: There is some interest in encryption schemes meant for humans to perform without computational aid. (Relevant questions here, here, and here.) People often cite the VIC pen-and-paper ...
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Why is a MAC verification algorithm required when we can simply create a new MAC and compare the received one with the one calculated?

The process of verifying integrity through MAC involves two separate algorithms (as mentioned here). On the server side, a signing algorithm runs which calculates ...
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How would I get started in auditing and finding vulnerabilities in encryption algorithms?

I know, it sounds dumb. Very dumb in fact. But regardless, I want to actually begin doing security research on cryptographic algorithms (SHA, RSA, ECDSA, etc.). I would prefer that this question be ...
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How to devise cryptographic system with data-sharing ability and password reset

I originally posted this in the security.stackexchange forums but then I was directed to this one which seems more befitting for my question. I am writing a C# .NET application. For my application the ...
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Looking for a way to enlarge a message so that any modification to the “enlarged” message makes recovering the original message impossible

Let's say we have a message m of small size. I am looking for a system $S$ so that $S(m)$ is arbitrarily large, we can easily compute the inverse $I(S(m)) = m$, and any modification to $S(m)$ makes it ...
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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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Generating a recovery phrase for a RSA key-pair

What is an optimal way to associate a RSA key-pair with a recovery phrase/seed for access recovery purposes? I've seen a lot of cryptocurrency wallets provide this feature, however, I'm not looking to ...
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Is choosing $1$ as a public exponent valid in RSA?

I know it will not encrypt anything. But is $1$ valid as a public exponent in an RSA public key?
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How to solve high exponent attack for same message in RSA

I know Håstad's broadcast attack when e = 3, but what if e = getPrime(randint(350))?
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How Should Form Input be Encrypted for sending to a Server?

I apologise if this question is a duplicate. I couldn't find any similar questions. I am writing a web app that consists of a series of drop-down style question menus. These generate more drop-downs ...
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Is it easy to crack a hashed phone number?

I want to SHA256 hash phone numbers in order to hide them. Is this a good idea? Are there any other ways I could make this safe?
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randomness of encrypt

In the paper "Efficient Encryption from Random Quasi-Cyclic Codes" of Gaborit et al. p.14, I read "Encrypt$(pk=(G,Q,s),\mu,\theta)$: uses randomness $\theta$ to generate $\epsilon \...
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RNG randomization strength for PRF seed

Consider a use case that requires the creation of multiple asymmetric key pairs. There are two options for generating random seeds for a PRF: Use a software based RNG and generate a new seed for each ...
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Sensible amateur usage of web crypto API

I want to know if my usage of the web crypto API is sensible. I want to use it for symmetric and public-key encryption and decryption, and signatures, but as a non-expert I am scared by the warning on ...
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Is storing salts encrypted a good idea?

I've read that storing password hashes in a database, you can store the salt in plaintext alongside the actual hash with no detriment to security. I was thinking that one could derive a key from the ...
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Generate version 3 x509 certificate from version 1 CA

Please do forgive me for my naivety. I have inherited a legacy system wherein the CA which signs the certificate is of version 1. Is it possible to generate a x509 version 3 certificate which is ...
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RNG to hide some bits

Suppose I have a sequence of bits of length M. I need to hide N out of M bits (hiding means forcing them to be 0) using RNG with a key. How I can relate the output of RNG to the number and positions ...
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How to provide secure password based encryption with password reset option

I am trying to build website that will encrypt some data for the user using his/her the output of scrypt on it, now the idea is that this schema is not flexible because if the user loose their ...
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Multi Factor Encryption?

I got an alert last night to the keywords above and was curious, so took a look at the tor site flagged which is the following one: http://nsrz5iogimqwgeax3clpp6hvfy6viom2woy7dghgxes4sqk63r7svoqd....
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Is AES ECB mode with salt and frame counter still comparatively weak?

Many advice against using AES in ECB mode as it always produces same cipher text for a given plain text. That shortcoming can be addressed by using salt appended to original message so that the ...
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Is it reasonable to consider that an encryption scheme must be invertible?

I am in a dispute regarding a test question in an exam. The question is something like that: What would happen if one were to use RSA with $n=100$ and $e=13$ to encrypt a message $m$? a) You would be ...
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Why AEAD instead of encrypting with a simple hash?

I hear a lot about AEAD encryption (GCM, EAX, ...). Why is it unsecure (it seems to be as AEAD exists) to do do that: Imagine a block of data, hash it, append the hash to the data, then encrypt the ...
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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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Why does Encrypt-Then-Sign not yield a CCA-secure public-key encryption scheme?

In symmetric cryptography, combining an IND-CPA secure symmetric encryption scheme with a secure MAC with the encrypt-then-MAC method yields a IND-CCA secure symmetric encryption scheme. I am trying ...
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Reducing a 64 digit integer to 10 digit

Situation:- I am using Python. I am using RSA and I am using two 64 bit keys. I am not an cryptographer . I can provide you the RSA code if needed but i am not posting it as it doesn't have to do ...

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