Questions tagged [cryptography]

Questions relating to cryptographic topics such as encryption/decryption and hashing. (Not for use with trivial ciphers.)

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3answers
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A Caesar cipher in Python3

This code basically just does a Caesar cipher on the contents of the variable "s" with a shift of 1. Sorry if the comments on the code don't explain it well. I'm quite new to Python and I'm not very ...
13
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4answers
3k views

Fast symmetric key cryptography class

I am trying to build a fast cryptography algorithm. The algorithm works fine, but I am worried if there are any potential flaws that might make the algorithm vulnerable to any kind of attack. Here is ...
2
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0answers
220 views

XXTEA encryption implemented in modern C++

At the company i work we have a system where an user is presented with a question and some alternatives to choose from. The question and answers are generated at runtime. In order to simplify the ...
4
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1answer
270 views

Python Secure Implementation Of AES-256-CTR Using Cryptography.Hazmat

I've implemented a wrapper for AES 256 CTR mode using the cryptography.hazmat module, I am wondering if there are any vulnerabilities in my implementation, specifically about the counter and its ...
5
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1answer
268 views

Encrypting credit card data

I need an encryption algorithm that would be secure enough to store credit card data. So it should be reasonably secure. Here's what I've come up with. I'd appreciate any constructive criticism. <...
1
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1answer
45 views

Small service for hashing and validating passwords, using PBKDF2

As part of a larger authentication/authorization system, I've developed a small .NET Core 3.0 service for hashing passwords using PBKDF2 (with a salt) and validating passwords against a stored hash/...
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3answers
49 views

Implement state eraser for NIST DRBG and other crypto primitives using macro

As a spare-time personal project, I'm implementing a set of symmetric-key cryptographic primitives. One thing I've left vacant for a long time, is the key/state eraser, which I decide to add right ...
4
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2answers
194 views

C# Cryptography Interface

C# lacks a common off-the-shelf encryption and decryption interface for dependency injection. Nearly every codebase I've ever opened has a couple of extension methods for hashing strings and so on. ...
5
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1answer
266 views

Educational implementation of SHA256 in Rust

A few weeks ago I decided to have a look at the Rust programming language. After a few standard exercises I chose to try to implement the SHA256 hashing algorithm, because why not. The algorithm's ...
4
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1answer
100 views

Data encryption / decryption on Node.js

I've implemented my first data encryption / decryption methods on Node.js. Although it might look similar to hundreds of sample implementations available online, I'm curious to get a feedback. I'm ...
3
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1answer
108 views

kryptein cryptography package for Node.js

I have written a cryptography NPM package called kruptein. The code is also hosted on GitHub. Having used multiple "best practices" with regards to key management, algorithm selection, key size, iv ...
7
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2answers
854 views

A simple implementation of the principle of RSA encryption

Inspired by a Numberphile video I made a little program that shows the principles of RSA encryption and decryption. To calculate the keys I used the explanation in this link: rsa public private key ...
3
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1answer
120 views

Capsulation solution for byte arrays

In a part of the project, I had to implement a solution for encapsulation of byte arrays. We do use ssh and secure ports for socket connection but I was in need of an extra layer of protection against ...
5
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2answers
127 views

PLINQ code analysis in terms of efficiency of cryptographic hashes generation

I have the following code that I wrote in order to find the correct password by generating hashes out of all possible combinations and comparing each of them with the target. I'm trying to make ...
1
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1answer
130 views

Expose encrypted serial ID in Elixir

I'm working on a Phoenix/Absinthe application and I thought to expose encrypted sequential IDs instead of UUIDs since these are a bit shorter. Encryption on Elixir/Erlang seems very hard, so I think I'...
3
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1answer
77 views

A Tumbler, or a format-preserving-encryption shuffle

I wanted to implement a simple algorithm for encoding id of entries in a database to avoid: Storing the UID (unique id) in the ...
2
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2answers
160 views

Light Security Local-Machine Password Encryption

I have a program that makes a call to an SQL database. I cannot use SSH to connect to it (as far as I am aware) or any other more secure method, so Java's SQL connector was used. As the connection ...
11
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2answers
1k views

Implementation of the Jacobi Symbol in C

I am new to C programming and wrote the following algorithm for the calculation of the Jacobi Symbol. Though there are some faster versions of this algorithm available I am only looking for some ...
4
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2answers
100 views

File encoder/decoder in Nim

I wrote a simple program to encode a local text file with password and decode it back. There is one text file and it is either encoded with a password or is in plain text. I had a version in Python ...
4
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0answers
91 views

SHA256 implemented in Rust

I just finished making an implementation of a SHA256 hashing function (https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.180-4.pdf) in Rust and I was looking for some feedback. As far as I can tell it ...
4
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1answer
92 views

PRBHA-10: A hashing algorithm in Python

So I've been working on a simple little hashing algorithm for Python that I like to call PRBHA-10 for short, or Pseudo-Random-Based Hash Algorithm. This is a hash algorithm in Python that is meant to ...
9
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1answer
82 views

Fun crypto problem: Exploiting a vulnerable encryption scheme with Python

I came across a question asked here and here on the Crypto Stack Exchange site, and decided to analyze it as a kind of case study. To demonstrate the concept, I wrote a short python script depicting ...
7
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2answers
354 views

Finding collisions of the first few bits of a SHA-1 hash

My objective is to find a hash collision of my modified hash function. Assuming my modified hash only outputs the first 36 bits of SHA-1. As we know, SHA-1 is a 160-bit hash value, hence, we only need ...
3
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1answer
265 views

File Encryption using pynacl

I need a rather simple file encryptor/decryptor in Python, after some research, I decided to use tye pynacl library reading the file in blocks, writing them back out, and then at the end using Blake2b ...
15
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1answer
244 views

Security audit of open-source, RSA Blind Signature library

I've just published a small library implementing the RSA Blind Signature process. Here's the GitHub repo! I needed something portable, and easy enough to use that I could ask other people to ...
3
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0answers
56 views

Atbash cipher in Ruby

I implemented my own spin on the Atbash cipher in Ruby: ...
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1answer
96 views

employing AES algorithm in Java

I have employed an AES algorithm in order to encrypt files within a GUI. I was wondering if my algorithm is secure. Could I change anything to improve it? Is my IV secure and is it producing different ...
4
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2answers
164 views

F# wrapper to generate SHA256 signature for a file

I've created the following module to allow me to generate a SHA256 signature for a file. (In real life this is used to verify an image file hasn't been amended). The cut down code looks like this: <...
2
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0answers
25 views

RC4 in Sinclair BASIC; Working around one-indexed arrays

This is a program written in Sinclair BASIC (48 BASIC) for the Sinclair ZX Spectrum. It uses a hardcoded key (null right now) as seen in the bottom and outputs a stream of integers generated with RC4. ...
2
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1answer
566 views

Cryptographically secure token generation in C#

Is the following a cryptographically secure way to generate a random token? Does it have any of the predictability risks that are theoretically associated with using a GUID as a token? ...
12
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2answers
2k views

Employing 3DES algorithm in Java

I am making a project just for fun that employs the 3DES algorithm in Java. I was wondering if my algorithm looks secure. Is there any advice or feedback you could give me? Do I need to include an IV? ...
2
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1answer
114 views

Encrypts using AES GCM for data with limited visibility and long rest

This is the third iteration of my venture on creating an encryption/decryption solution. I asked a question here, which led to this question here, which led to this answer here, which led me to ...
1
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1answer
2k views

RSA wrapper written in Kotlin

I've written up a small wrapper for RSA and AES encryption in Kotlin, and I want to make sure I'm not making any glaring mistakes before use it. This is going on a small project with basically no ...
1
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1answer
267 views

Encrypts using AES with random initialization vector meant for data with limited visibility and then long rest

I've done some research, reviewed countless SO questions that appeared similar, leading me to endless rabbit holes. My solution is working, but I don't like it. I want to create a random IV for AES ...
5
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2answers
881 views

Python AES-CBC implementation using AES-ECB

I am looking for ways to make this code more "pythonic" and any issues with my implementation. This was designed to solve Crytopal's Challenge 10. This challenge requires recreating the AES-CBC cipher ...
5
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1answer
45 views

High performance wrapper for CSPRNG arc4random(3)

This function is a wrapper for arc4random(3), a cryptographic pseudo-random number generator on macOS and BSDs, but you can also get it by installing ...
4
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1answer
1k views

Naïve RSA decryption in Python

I am making a code with basic RSA encryption/decryption. My professor wants me to speed up this function but it is already so simple and I am lost. Any ideas? ...
2
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0answers
500 views

Python RSA/DSA File Cryptography, Key Generation, Key Protection

I have forked a previous version of my script, critiqued here: Generate public/private keys, encrypt, decrypt, sign, verify This program allows you to encrypt and decrypt raw files using RSA keys ...
8
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3answers
351 views

Generate public/private keys, encrypt, decrypt, sign, verify

My program generates public private keys, encrypts, decrypts, signs and verifies, while using AES for the bulk of the data for speed, and encrypts the random key with RSA. Many operations were chosen ...
1
vote
1answer
500 views

Using encryption/hashing to create a secure login

I am creating a login for an encrypted chat application which retrieves login information from a MySQL database. I have got to the point where I feel pretty confident that (to the best of my knowledge)...
1
vote
1answer
73 views

Encrypt data to be send from service to service

I'm working with another company in a new application for my company. My job right now is to send on demand to the other company the data that they need, ciphering some of it. I should point out that ...
2
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1answer
81 views

Crypto for a funny contest with friends

I am participating in a funny crypto contest with my friends. This time, we raised the bar quite a bit. The code below is my take for the constraints we set. Note that on my machine, the code works ...
3
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0answers
423 views

Verify OpenSSL RSA signature (PHP) with .NET (VB)

I would like to achieve something I believe is pretty standard: A) My VB.NET client (ideally targetting Framework 4.0) sends a text string to my Apache/PHP Server via an HTTPS POST request. B) My ...
6
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2answers
403 views

RSA c implementation

This is my first attempt to implement a crypto algorithm. I am using C and gmp to interact with big numbers. Here is my code; you can run it after having linked with the ...
5
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1answer
150 views

First encryption program

This is the first piece of code that I write that's not just an exercise but a full program I can actually run. Features: Generate random letter/number pairs for each "printable" ASCII character ...
2
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2answers
83 views

Checking hash and passwords with a wordlist, more efficient

I have done a small code in which with a wordlist (out68.lst) I get the passwords from the hashes in the file 'shadow3'. ...
10
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1answer
912 views

XTEA Block Cipher

Usually people recommend to never implement cryptographic algorithms yourself unless you are an expert in the field. This of course makes a lot of sense mainly because there are numerous things that ...
7
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1answer
233 views

Frequency Analysis & Chi-Squared Test

Following up on my implementation of Cryptopals Challenge 1, this is my solution to Challenge 3. Single-byte XOR cipher The hex encoded string: ...
1
vote
1answer
95 views

Spring API that performs RSA encryption with exception handling [closed]

I'm creating a rest api using Spring which utilize javax.crypto as library to do some encryption stuff. While everything works well, I'm curious whether the error handling like this is acceptable or ...
3
votes
1answer
989 views

Secure password hashing implementation with salt and pepper

I share below my password hashing implementation with salt and pepper in C#, for your review and feedback. In my implementation methods like ValidatePassword(), ChangePassword() are in the user class. ...

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