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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What encryption mode should I use to protect CAN bus communication?

I have a CAN bus project and I should encrypt the communication between nodes using the AES algorithm. Which encryption mode should I use?
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The modes of encryption that preserve the format

Can anyone give me some documentation on the various format preserving encryption modes?
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Trapdoors for Lattices: CCA-secure encryption

In Trapdoors for Lattices:Simpler, Tighter, Faster, Smaller, Micciancio and Peikert proposed a CCA-secure encryption. However, I am confused about the step in decryption algorithm (p.36 Lemma 6.2.). ...
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Why don't we use Blowfish if it hasn't been cracked?

Since Blowfish is old, well-audited, and has no published attacks, why are we using AES instead? I know that Bruce Schneier said that Blowfish is insecure and told people to transition to Twofish, but ...
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Different encryption standards and how they relate to auth and algorithms

The main confusion I have is around the different PKCS and relation with SSL (TLS). I have done a lot of research and have found bits and pieces but not necessarily how these relate, so let me explain ...
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Implement a homomorphic encryption library

I want to implement the BFV and CKKS schemes in a homomorphic encryption library (similarly to how Microsoft SEAL and PALISADE work, but from scratch). Do you have any recommendations for papers or ...
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Using authenticated encryption along with signing

I know of a project that implemented e2e encryption using both authenticated encryption and public key signing. So the ciphertext produced for a message would be: ...
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Why should a distribution being pseudorandom strictly be a sequence of distributions being pseudorandom

According to Katz Lindell book, Let Dist be a distribution on l-bit strings. Informally, Dist is pseudorandom if the experiment in which a string is sampled from Dist is indistinguishable from the ...
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How an ID based encryption system simplified certificate management in e-mail systems?

I was reading a paper on Identity Based Signature. A line in it reads: The original motivation to build an encryption system based on ID was to simplify certificate management in e-mail systems. Can ...
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Deterministic generation of secure private keys from parent private key

is it possible to generate set of child private keys from one parent private key, generated by ECC for example, securely? So that new private key (and derive public key) could be used for encryption ...
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Semantic security of the OCB mode

As defined in the specification of OCB, the tag depends only on the checksum (that is just the binary sum of plain blocs), so if we construct two messages that have the same sum (this is very easy to ...
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Conditional decryption

Is it possible for one party to encrypt some data and have another party (unknown to the first party) view that original data if a certain condition is met? I cannot find any information about this ...
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Why are RSA ciphertexts different for the same plaintext?

I am using SpongyCastle for a project on android. I have used RSA to encrypt the data and then decrypt it in another activity, the keys are stored in the shared preferences. I discovered a thing I ...
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Is overflow-ing possible in CKKS FHE scheme?

I'm using the CKKS Fully homomorphic scheme using Microsoft SEAL, and wonder what will be the result of overflowing a certain floating point variable? Is it even possible to do so? I found a statement ...
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Is there a secure way of allowing users of my app to selectively share data from an external service?

Is there a secure way of allowing users of my app to selectively share data from an external service with my app? In order for the users of my app to get their personal data from the external service ...
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Decryption formula of Plaintext Block Chaining (PBC) mode of a block cipher

Considering that $C_n = E_k(M_n) \oplus M_{n-1}$ formula is used in encryption side of this mode of block cipher, and knowing that instead of M0 a randomly chosen initialization vector (IV) is used in ...
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Is it illegal to export pythons cryptography.fernet library to any countries? [closed]

I've created a python program that includes cryptography.fernet in order to hide user passwords. This program will likely be shared with other employees in China, Tailand, Ireland, etc. Is this python ...
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What is the need for Diffie-Hellman key exchange when we have asymmetric encryption?

I am new to cryptography and I am having a hard time to understand what is the need for DHKE procedure. I think I fully understand the principle in which it happens and also the mathematics behind it ...
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Is there any chance of failure in Cryptography

With my limited knowledge of cryptography and its correct terms, functions (md5, base64, sha, aes or whatever) turn an input into encrypted output. For example, if the following input turns into ...
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Using raw encrypted network data for randomness

I've read that encrypted data should be, theoretically, indistinguishable from random data. Using this principle of encryption, could I combine encrypted network traffic streams to generate either a ...
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I need to try to find an algorithm to decode a set of Excel dates [closed]

I need to try to find an algorithm to decode a set of Excel dates. A former employee once told me he could encode a date in Excel and no one would ever figure it out, he said "like a needle in a ...
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Verify correct answer transparently

The following problem needs to be solved: Person A will be guessing the number that Person B has in mind. Only Person B can confirm that the answer provided by Person A is correct. Person A can not ...
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More than one private key for RSA

In an RSA-encryption scenario, Bob's public key pair $(n, e)$ is $(143, 43)$. An attacker Mallory tries brute-force and comes to $d = 7$ as the private key. The value of $φ(143) = 120$ is not known to ...
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What is the use of key iterations?

I read about PBKDF2 on Wikipedia and seen few apps. having option to manually enter number of iterations. I am still not clear on this. (1) With what I understood, key iterations can be used only ...
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Can the hash of the ciphertext be derived from the hash of the plaintext

Let $C$ be a symmetric cipher $H$ a hash function. Alice uses $C$ with a key $k$ to encrypt plaintext message $m$ yielding ciphertext $c$. She then calculates the hash of the message $h_m = H(m)$ and ...
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Aes 128 input and output size [closed]

I'm novice in encryption, i want to use aes 128 to encrypt can bus communication but the can bus data size is different from aes input and output (16 byte) ! How can I modify aes input and output size ...
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plaintext decrypted form a cipher text using key = 3 in Caesar Cipher and that plain text with the following ciphertext to get the key [closed]

how to use the plaintext from that was decrypted form a cipher text using key = 3 in Caesar Cipher and using that plain text with the following ciphertext to get the key.
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How can Whatsapp identify forwarded attachments

Sometimes Whatsapp shows that an attachment was often forwarded. How do they know this if the message is end-to-end encrypted? Even with hybrid encryption I encrypt with my key and store my attachment ...
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Actual RSA encryption & decryption of strings?

$K_{pub} = (n, e)$ $K_{pvt} = d$ Then $E_{K_{pub}}(x) \equiv x^e \mod n$ Practically, when RSA is used to encrypt strings, what is the $x$ here? You cannot take it byte by byte because $\mod n$ will ...
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How should I assign a letter at random to another?

For my first ever project in Python, I wanted to code a cipher to encrypt simple messages ( no spaces or lower case to avoid that extra hassle for now ). My idea was to either: Choose a letter of ...
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Diffie-Hellman and identify with certificates

alice and bob use the Hellman-diffie protocol to exchange keys and identify each other with certificates, signed by a trusted certifier (CA) and each has a private key that matches the public seducer ...
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Are basic replacement ciphers always bad for structured data encryption?

I have read that basic replacement ciphers, such as replacing one byte with another specific byte at each location, are far less effective with non-randomized data. My question is, can this problem be ...
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How to sign messages using the NOISE Protocol Framework?

I wanted to learn more about secure messaging and started a personal project using the libhydrogen library. From my understanding, instead of using public-key ...
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Does this algorithm have a name? (Distance between letters)

This came to mind the other day and I'm wanting to know if there is a name for the following algorithm (I'm not sure if "cipher" is the right word for it): Take two consecutive letters at a ...
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How to generate a collinear point without revealing one of the existed two points?

Assume we have point $A(x_A,y_A)$ and point $B(x_B,y_B)$, and now we want to generate a point $C(x_C,y_C)$ so that $A,B,C$ are on the same straight line. All mod $p$. If $A$ or $B$ could not be ...
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Encryption algorithms that require more work to decrypt versus encrypt?

Are there any encryption algorithms that require significantly more work to decrypt, versus the amount of work required to encrypt? I'm looking for a method of fast encryption, but which will require ...
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Making a cipher non-malleable using a plaintext transform?

NOTE: By malleable/non-malleable, I mean the ability/or not to change a byte/block of the ciphertext and have it change only that byte/block of the plaintext. I understand that we use authentication (...
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Can a shift cipher attain perfect secrecy?

On a practice question for my intro cryptography exam, it asks the following: Assuming that keys are chosen with equal likelihood, the shift cipher provides:    A) computational security    B) ...
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Anatomy of an RSA private key

I'm learning about OpenSSL and public key infrastructure and am curious about the structure of an RSA key and how it's related to its corresponding public key. I can generate a private RSA key with ...
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How to correctly implement an archetypal encrypt-then-MAC AES-CTR + HMAC mode cipher?

I've created an AES implementation in Python as a learning experience (mainly for encrypting/decrypting files), and wanted to make sure that I haven't made any huge mistakes in my logic (of course, ...
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Bit Flipping Attack on CBC Mode

To perform a bit flipping attack, the previous block is modified by using XOR. This results in an altered plaintext. However, now the ciphertext of the previous block is altered, hence it will result ...
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Deterministic Encryption - Generating IV from password key

I need to encrypt file and directory names/paths but I need the encryption to be deterministic. I need to sync the local files with a cloud storage provider so I can't use probabilistic encryption. ...
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Looking for encryption function given decryption function (2048-bit ciphertext and key, addition and subtraction operations)

I have a decryption algorithm for 256-byte (2048-bit) blocks and want to find the matching encryption algorithm. What I know about the algorithm and have: 256-byte ciphertext (I have multiple ...
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Would a key recovery attack on ChaCha's keystream would be made more secure with an AONT?

To be clear I'm well aware that ChaCha doesn't need to be "improved". Also, I have no intentions or misguided ideas about trying to "improve" it. My question is hypothetical, and ...
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SHA-512 Encipherment via CBC

I wrote a cryptographic function that encrypts a plaintext by using a series of SHA-512 hashes that are used to encrypt the data via a simple byte-to-byte XOR. In order to prevent various attacks, I ...
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ESP header and trailer

I investigated the IPsec Protocol. I am wondering if I can remove/reduce any field to save space, is there a way to save overhead in ESP packages?
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Constructing a commitment scheme from two (possibly defective) commitment schemes

If we have two commitment schemes Com1 and Com2, which are possibly defective (in the sense of not satisfying hiding or binding properties), is it possible to construct a commitment scheme which does ...
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Identification Schemes and Internet of Things

I was reading an article titled "A Novel Method for Polar Form of Any Degree of Multivariate Polynomials with Applications in IoT" (doi:10.3390/s19040903) I read the following statement: &...
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RSA algorithm implementation

$$m^{ed} \equiv m \bmod n$$ $n =pq$, so by Chinese Remainder Theorem it is equivalent to $$m^{ed} \equiv m \bmod 𝑝, m^{ed} \equiv m \bmod q$$ where $n=p\cdot q$ So how did 2 come from 1 by the ...
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Is there a way or how to predict the output size as a result of encryption?

Is there a way or how to predict the output size as a result of encryption from 3DES, AES-128, AES-192 etc ? So that I know how to store them in the data in DB given a known possible clear text length....

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