Linked Questions

162 votes
6 answers
262k views

Why most people use 256 bit encryption instead of 128 bit?

Isn't 128 bit security enough for most practical applications?
H M's user avatar
  • 2,987
93 votes
4 answers
22k views

Will quantum computers render AES obsolete?

This is a spin off from: Use multiple computers for faster brute force Here's at least one source which says that quantum computers are on the way to being able to break RSA in the not too distant ...
BuvinJ's user avatar
  • 1,003
68 votes
6 answers
29k views

Pattern to allow multiple persons to decrypt a document, without sharing the encryption key?

Current setup We have a service that allows users to upload documents through a website and stores the uploaded documents encrypted on disk. The documents on disk are encrypted with a per-user key, ...
Monika's user avatar
  • 1,092
35 votes
11 answers
12k views

One liner to create passwords in linux?

How do you create a readable password using bash with one line? What if i'm looking for 128 bits of entropy? EDIT By readable I mean the 94 printable ascii characters (without space). It can use ...
András Gyömrey's user avatar
28 votes
3 answers
7k views

Use multiple computers for faster brute force [duplicate]

I've watched Mr. Robot lately and can't stop thinking why it was so hard to decrypt files encrypted using AES encryption with a 256-bit key. Let us say the only method to find the key is through brute ...
Mero55's user avatar
  • 845
27 votes
7 answers
4k views

Is sha1sum still secure for downloadable software packages signature?

We use sha1sum to calculate SHA-1 hash value of our packages. Clarification about the usage: We distribute some software packages, and we want users to be able to check that what they downloaded is ...
Michael's user avatar
  • 1,469
55 votes
1 answer
43k views

Why use an authentication token instead of the username/password per request?

The author of https://stackoverflow.com/a/477578/14731 recommends: DO NOT STORE THE PERSISTENT LOGIN COOKIE (TOKEN) IN YOUR DATABASE, ONLY A HASH OF IT! [...] use strong salted hashing (bcrypt / ...
Gili's user avatar
  • 2,169
21 votes
6 answers
4k views

Can any password hash ever be secure?

My understanding is the the main reason MD5 is insecure, is that it can be calculated too quickly, allowing too many attempts to be tried. People recommend instead using a hash that has been designed ...
Benubird's user avatar
  • 326
20 votes
5 answers
10k views

Which hash-length is more secure?

If a hash algorithm has an option for selecting the output-hash-length (e.g., 128 vs. 512 bits), and all other aspects of the hash function are the same, which hash-length is probably more secure/...
rpach17's user avatar
  • 325
18 votes
4 answers
23k views

Calculate time taken to break AES key

A 256 bit AES key is required to be broken using the brute force method on a 2GHz computer. How long would it take to break the key in the best case and in the worst case situations? Assume that 1000 ...
Nadishan's user avatar
  • 283
27 votes
2 answers
45k views

Recommended options for LUKS (cryptsetup)

I'm looking for recommended options for cryptsetup to create fully encrypted SSD (SanDisk SSD U100 128GB), which achive: Timing O_DIRECT disk reads: 1476 MB in 3.00 seconds = 491.81 MB/sec Timing ...
Artur Szymczak's user avatar
19 votes
4 answers
38k views

What do key size and block size mean in cryptography?

Can some one simply explain the meanings and the difference between symmetric key and block size. Why 64 block size not safe any more and they increase it to 128 (AES,...,Serpent)? And what about key ...
rezx's user avatar
  • 1,069
22 votes
2 answers
1k views

Does holding an AES-encrypted string and its cleartext from a database help an attacker in decrypting other parts of the database

I have a question regarding Encryption. Say an attacker stole my entire database. In that database all the data was encrypted. If the attacker took one piece of encrypted data and for some reason knew ...
user2924127's user avatar
11 votes
6 answers
6k views

Most secure data storage?

What is most secure data storage currently available and suggested by specialists, to store digital data in digital medium (without making hard copy of data onto paper or other type of medium, than ...
Deele's user avatar
  • 263
20 votes
1 answer
24k views

Why is secp521r1 no longer supported in Chrome, others?

Found a few issue threads, notably for Chrome (Chromium issue #478225), and the browser does appear to have dropped support for the secp521r1 curve (can test your browser using SSLLabs). There were ...
AJAr's user avatar
  • 2,382

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