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Questions tagged [cryptography]

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

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4
votes
2answers
104 views

Sign an EC2/S3 URL Version 3

From the previous 2 versions: Sign an EC2/S3 URL Version 2 I fixed the comments from the previous version. Most of the code remains the same (so I have split out the new code for review). The main ...
5
votes
4answers
1k views

Encryption algorithm for an app

I have created an encryption algorithm for this app I am currently in the process of developing. I was wondering if my code looks "sharp", concise, and most importantly, succinct. I was also wondering ...
15
votes
2answers
1k views

ECDH implementation in python

I wrote an implementation of elliptic curve Diffie-Hellman key exchange in python. I would like to know if I could make it faster, cleaner or more secure: ...
7
votes
1answer
2k views

Am I using PHP Mcrypt the right way?

I have written a small wrapper class for using PHP Mcrypt for encrypting and decrypting text data. This class generates a salt for hashing the key and encrypts the given data with the generated key ...
6
votes
0answers
581 views

T-SQL Hmac (Rfc2104 SHA2_256) Implementation

I'm trying to implement an Hmac in T-SQL using this question as an guide. Please critique this: ...
14
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5answers
3k views

Cryptographically Secure Password Generation in C

I am looking for ways to improve my password generation code written in C. This is in the same vein as my code in C++ and Python with many improvements. I am using ...
3
votes
1answer
160 views

My images have secrets A.K.A. the making of aesthetic passwords V.2

This is my implementation of a prng steganography tool written in Python. You can also find the code on GitHub. Steganography is the art of hiding messages in (images, videos or even audio) I've ...
8
votes
2answers
170 views

Encrypted safebox

I am developing JSafebox, a portable safebox project written in Java. The goal is to provide a secured environment where the user can browse encrypted files without leaking data on the drive. The ...
2
votes
0answers
318 views

Python2.7 Some xor fun

After doing the Cryptopals challanges, which I found scrolling through codereview, and finally being able to solve set1 challenge 6. I decided to have a little xor fun, and make an automated xor ...
11
votes
4answers
7k views

My own SHA-256 code implementation

I'm worried about my code performance. The code I've written is an implementation of SHA-256 using pseudocode from Wikipedia. It works fine, but I want to speed it up. With a buffer of 4096 bytes, I ...
8
votes
3answers
4k views

Generate cryptographically secure random numbers in a specific range

A project I'm working on requires generating a random number of \$N\$ length to a very high degree of fair distribution between digits \$[0, 9]\$. That said, I used the ...
8
votes
3answers
191 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 ...
7
votes
1answer
2k views

Hashing a SecureString using Cryptography Next Generation

Goal: I needed to calculate the salted hash of a password, where the password is stored as a SecureString. There doesn't seem to be much .NET framework support for SecureString. In particular, none ...
4
votes
1answer
1k views

Python PBKDF2 using core modules

I'm trying to implement pbkdf2 in Python 2.7/3.4 without needing the pbkdf2 module. (I'm also trying to avoid using classes.) Any insight would be appreciated: ...
3
votes
2answers
3k views

Getting a hash string for a very large file

After reading about large files and memory problems, I'm suspecting that my code below may be inefficient because it reads the entire files into memory before applying the hash algorithm. Is there a ...
2
votes
1answer
5k views

AES Encryption/Decryption with key

Is this the best way to encrypt/decrypt data? And Is it good to store Generated InitVector and CipherText in database as Base64 String which is converted from byte[]? ...
2
votes
1answer
160 views

T-SQL Constant Time Comparison

Explanation is in the function. Please point out any egregious errors: ...
15
votes
1answer
338 views

Cryptographically-secure super-secret government message transaction machine

-Hello Agent. Are you on a secure line? -Yes, secured. -Good, in 30 seconds the launch codes will be in your e-mail's inbox. You now have the go. Are you ready for the package? -Yes. ...
10
votes
2answers
405 views

Password hashing and matching

I took information from a series of posts and some prior knowledge to implement the following hashing algorithm. However, there is a lot of talk about what implementations are secure and not secure. ...
7
votes
3answers
435 views

Secure password hashing implementation

I'm implementing a password hashing method for a website. The code below is part of the User class. Any pointers on what I could do better? ...
5
votes
2answers
348 views

Encryption program for a messenger app [duplicate]

I am building an encryption program for a messenger app I am developing. I was wondering if the code looks clean and succinct, and at the same times is safe and secure: ...
4
votes
2answers
173 views

Sign an EC2/S3 URL

The other day I found myself trying to walk through the instructions for signing an S3 URL. http://docs.aws.amazon.com/general/latest/gr/signing_aws_api_requests.html Not as trivial as the ...
3
votes
2answers
280 views

DIY String Encryption

I was asked to make a String encryption utility without using encryption API. I basically had to come up with my own encryption methodology! the program was to be able to encrypt a string and decrypt ...
2
votes
1answer
7k views

AES-128 Encryption/Decryption of NSData

I recently found an Objective-C extension on NSData that encodes and decodes data with AES-128. I made an attempt to port this code to Swift 2.2: NSData+AES.swift ...
2
votes
2answers
66 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'. ...
2
votes
1answer
43 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 ...
2
votes
1answer
60 views

Sign an EC2/S3 URL Version 2

Follow up on previous review: Sign an EC2/S3 URL I have fixed the previous comments. I have also added the code needed to sign HTTP header fields as part of the request. ...
2
votes
2answers
1k views

String Encryption

I was asked to make a String encryption utility without using encryption API I basically had to come up with my own ecryption methodology! the program was to be able to encrypt a string and decrypt a ...
1
vote
0answers
689 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. ...
1
vote
1answer
355 views

Encryption via multiplication of hex-converted, multiplied ASCII values

The idea behind the encryption is that it stores the key within the final encrypted password. When the user inputs a password for the first time, they also have to pick an element from a list of ...
1
vote
1answer
51 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 ...
0
votes
1answer
148 views

ECDH implementation in python (part 2)

I worked a while on my code I posted here to make it more flexible and hopefully a little bit more secure. My goal is to implement a secure library for elliptic curve cryptography. ...