Questions tagged [cryptography]

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2
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2answers
146 views

Programming a library in multiple languages

I am planning to implement a cryptographic library for several languages and looking for best practices. I have looked at several threads, especially this, this, and this one, which answer my ...
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1answer
81 views

C# Destructors in RSA Crypto

I'm just reviewing some of my code and thought I'd throw this out there for comment. I have a factory class that builds and returns a class for RSA Crypto tasks. It implements IDisposable. All the ...
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1answer
67 views

Does the SHA256 hashing algorithm change based on the content encoding?

I am starting to look into how to implement SHA256 in JavaScript, and found this for example. It requires UTF-8 encoding it sounds like. Another one I saw required/supported only ASCII encoding and ...
1
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1answer
68 views

Do you need to implement TLS versions < 1.3 if you were to implement a TLS supporting library today?

I am looking at all the green and red boxes here, and am wondering what it would look like if one were to "implement TLS" today? What should you implement if you were to implement TLS today? Do you ...
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1answer
109 views

How to eliminate transparent memory copy in runtime?

Despite various ways to scrub sensitive data in volatile memory (see Survive DSE or Zeroing buffers), programs tend to perform transparent memory copies (such as a Garbage Collection). The newly ...
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1answer
114 views

Encryption key on passwordless authentication

A PHP based webshop running on a shared hosting stores libsodium encrypted personal data in it's MySQL database. To let users have access to their own data, a design very similar to the one discussed ...
-1
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1answer
95 views

Pattern to encrypt / decrypt data to / from a server without entering the secret key each time?

The title maybe it's a little bit confusing but I am certain that what I want to achieve is a common pattern, even if I didn't found anything on internet. I'm developing a web app that store ...
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1answer
295 views

How to store private ssh keys for my application?

I 've a pair of private and public ssh keys, which I'm using in encrypting and decrypting my JWT. So I'm creating and signing my JWT with my private key and shared the public key with the client who ...
0
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1answer
71 views

More explicit explanation for password authenticated key retriveal

How can i realize password authenticated key retrieval? I found some description of PAKR: A PAKR (Password-Authenticated Key Retrieval) protocol and its multi-server system allow one party (say, ...
0
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1answer
98 views

Domain model and feature Crypter

In my project I must implement a feature for encrypting some information when it is written into the database, and decrypt the information when it is reloaded. Should this concept be implemented in ...
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0answers
188 views

Storing File URI and Checksum to check if the file was changed in future

right now application is storing a file data in database and we are considering instead to store a link (http, ftp, etc) to the file and its checksum. We will only provide a service and the service ...
-3
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1answer
69 views

Creating a multiplatform (IOS, Javascript, and JAVA) linked user account database

I have done weeks researching this question for my App Idea. Background of the APP - Simply a multi crypto currency wallet which users sign up with ONLY username and Password - no email, FB, or ...
4
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3answers
3k views

What is an example for a one-way hash function?

I am doing a bit of research on hash functions. I understand the concept that it is an equation that is easy to do one way (you take the number 00011010 for example and do reasonably simple math with ...
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1answer
121 views

Proof of digital document integrity

Let's say we have the following scenario. We have user A and user B and an initial digital document D generated by B. What algorithms and infrastructure are required in order to guarantee/prove ...
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1answer
231 views

Should I encrypt my cookies using AES?

I'm going to encrypt the following data (server side): email, IP, username { *IP*: { email: *email at this IP* username: *username of email IP* } *IP2*: { email: ...
0
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1answer
126 views

Apart from immutability, does blockchain offer any other advantages?

I am trying to understand the broader implications of blockchain apart from the main advantage of immutability. Are there any? It seems like the distributed nature of the ledger can be an asset when ...
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1answer
188 views

Can RSA be used to secure client data before sending to server? [closed]

So one day i was reading about RSA and over there it was written that we can secure the data using the public key. So as an idea can I secure the data on the client itself before sending it to the ...
4
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5answers
952 views

Whats safest way to tell if decryption was successful?

I'm making a C program that uses GTK3 (best documentation ever) and OpenSSL (worst documentation ever) to simply encrypt/decrypt a file using a password. The encryption and decryption functions are ...
0
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2answers
61 views

Allowing only users of the official client to upload media to my server. Possible?

I've been toying with a project idea for a while now but can't quite settle on one important detail. The plan is to write a client that can author and upload WebMs to a server for global viewing (...
0
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1answer
1k views

Algorithm to create a superincreasing sequence

I am building an implementation of the [Merkle-Hellman Knapsack Cryptosystem] for my study.(https://en.wikipedia.org/wiki/Merkle%E2%80%93Hellman_knapsack_cryptosystem) One of the things I would like ...
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1answer
1k views

How to generate random Boolean functions in Algebraic Normal Form in Python?

I am looking at A SAT-based Public Key Cryptography Scheme and got inspired to challenge myself to write an implementation of this Cryptography Scheme on Python. A part of the cipher encoding would ...
1
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1answer
107 views

Simplistic non-secure example of public key encryption

I'm giving a lecture to novice developers on security and would like to explain ssl and the basics of certificates. For this I would like to convey a vague intuitive understanding of asymmetric key ...
0
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1answer
505 views

How does Luhn algorithm relate to cryptograpic hash functions?

What I am interested is the similarities and differences between the two. It is my understanding to present time that Luhn algorithm is a type of checksum function same as some cryptographic hash ...
1
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1answer
171 views

Personal Digital Signatures in Web Applications [closed]

In order to sign data with personal digital signature in a web application, server side languages like PHP can do the whole job, but that would require that the user uploads his private key, lets say ...
3
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1answer
137 views

What is the origin of the phrase “extirpated as a potential munition”

I recently came across this statement in the Perl documentation: extirpated as a potential munition derived from the sentence: "Creates a digest string exactly like the crypt(3) function in the C ...
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1answer
471 views

Question on RC4 algorithm

I started reading RC4 from a book and was not able to understand some phrases correctly. The RC4 algorithm is remarkably simple and easy to understand. A variable length key of from 1 to 256 bytes ...
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2answers
3k views

What kind of applications are built using C [closed]

I studied C programming about ten years ago, whiles in Uni,however I would like to pick it up again. I'm looking at developing secure applications that utilize cryptography. Would C be the right ...
3
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1answer
955 views

Hash function with uniqueness guarantees and controllable entropy

Is there a class of hash functions that meets the following specs: Upper and lower bound can be specified Uniqueness is guaranteed as long as the input is between the upper and lower bounds Amount of ...
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7answers
4k views

Is there any algorithm pattern to protect any content in the web to ensure I am the first one who created it?

A few years ago there was this hacker (don't remember who he was) that full disclosed a vulnerability in a given system, but to make sure nobody took credit for that, he created some kind of PGP key. ...
4
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1answer
6k views

Difference between reverse lookup tables and rainbow tables

Using Reverse Lookup Tables, you create a lookup table consisting of the password hash of user accounts. Then you use another table which consists of hashes with guessed passwords. Then you compare ...
0
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1answer
93 views

Does inserting/removing random characters in a string count as cryptography?

I'm making an iOS game. All developers need to determine whether their app uses cryptography or not. My game saves files in the Documents folder. They are .plist files representing dictionaries. They ...
2
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2answers
267 views

How faster could a dedicated chip do sequential squaring modulo operations to break a time crypto capsule?

I'm facing a very real problem and, sadly, I cannot find the answer on my own: I'm hitting my limit as a programmer because my hardware knowledge is not sufficiently advanced at all. It's an issue I'...
2
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5answers
2k views

secure photos on server [closed]

I would like to hear advice from the more experienced developers. The project is now in the design stage. It's mobile application and a simple web application. Content is pictures, comments, personal ...
0
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2answers
359 views

Snapchat clone: How do I secure pre-downloaded notifications so that they cannot be opened outside of the app?

Say I'm making a snapchat clone app for Android and iOS. Let's say that I get a snapchat from Baz. I want to pre-download the audio for this snapchat. However, as the developer, I want to secure this ...
27
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5answers
32k views

Where to store the private key?

Say I want some parts of my software to be encrypted. For example, the credentials for a database, etc. I need to store those values somewhere, but doing so in cleartext would make it easy for an ...
0
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1answer
1k views

deciphering columnar transposition cipher

I am looking for an idea on how to decipher a columnar transposition cipher without knowing the key or the length of the key. When I take the cipher text as input to my algorithm I will guess the ...
127
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1answer
11k views

What are the advantages and disadvantages of cryptographically signing commits and tags in Git?

So someone peer reviewed my work, and he told me that I should always sign my commits and tags cryptographically. When asked why, he didn't know to explain it to me, and said "It's just a good thing ...
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2answers
916 views

What is the best programming language to do crypto running time measurement? [closed]

I am trying to measure the running time of different crypto algorithm. e.g. how long it takes to encrypt/decrypt a block of plaintext. May I ask if C with OpenSSL is the best PL to do this?
5
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2answers
3k views

How to manage my private key for signing .NET assemblies?

I write open source .NET class libraries as a hobby and thought about signing them. I can get Visual Studio to generate me a password protected public/private key pair and save it as a .pfx file, but ...
1
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1answer
625 views

Are python's cryptographic modules good enough?

I mean, say you were writing professional grade software that would involve sensitive client information. (Take this in the context of me being an amateur programmer.) Would you use hlib and hmac? ...
1
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1answer
544 views

Using a random string to authenticate HMAC?

I am designing a simple webservice and want to use HMAC for authentication to the service. For the purpose of this question we have: a web service at example.com a secret key shared between a user ...
3
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4answers
613 views

Public-private key pair handling on a Windows ecosystem

I've been thinking about how to architect an infrastructure for one of our business applications with the following requirement: Data written by some user can only be read by that user and his ...
15
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1answer
9k views

Java Cryptography Extension

I was told that in order to support AES256 encryption inside my Java app that I would need the JCE with Unlimited Strength Jurisdiction Policy Files. I downloaded this from Oracle and unzipped it and ...
2
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1answer
379 views

What alogrithm is used on the smart cards for the DNSSEC Trusted Community Representatives?

I've been doing some reading about DNSSec and am interested in the algorithm that they chose to use when splitting the trusted key up between the 7 Trusted Community Representatives (TCR). I ...
0
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1answer
4k views

C programming in Windows 7 [closed]

Which is the best book and what are the best tools for C programming in Windows 7? Would using C in any way hinder me when it comes to using the Windows API as opposed to using C++ or C#? I would ...
21
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4answers
5k views

Programmers' concerns about export restrictions from the United States

Which aspects do I need to consider when designing and publishing software that must meet the US export restrictions for cryptographic software? Wikipedia says that there are various categories which ...
4
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1answer
322 views

What was the earliest use of cryptographic tokens in URLs?

I was wondering: it now seems to be more and more common to see people/framework putting cryptographic tokens in the URLs their webapps are generating (to prevent quite effectively against quite some ...
5
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6answers
3k views

How can I prevent users from creating multiple accounts on a web site?

I'm building a site that needs to guarantee user reputation scores are accurate by preventing users from creating more than one account, at the cost of decreased user signups. So far, the only ...
7
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3answers
375 views

Using a standard localised data cryptography pattern with an ASP.NET MVC3 application

I have been given the task to rejuvenate an existing Human Resources application from Access into ASP.NET. This is a strictly internal application, and I have no problems developing it within our ...
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4answers
658 views

MD5 implementation notes

While going through RFC1321, I came across the following paragraph: This step uses a 64-element table T[1 ... 64] constructed from the sine function. Let T[i] denote the i-th element of the ...