Linked Questions

42 votes
6 answers

What does it mean for a random number generator to be cryptographically secure?

I've never heard a good answer. I'd like to hear details about: What are the criteria that make an RNG cryptographically secure? Why must your RNG be cryptographically secure? I.e., what are the ...
agotsis's user avatar
  • 547
24 votes
4 answers

Is it feasible to build a stream cipher from a cryptographic hash function?

A few years ago I devised a symmetric-key system that worked like so: ...
John Gietzen's user avatar
  • 1,505
7 votes
3 answers

A simple block cipher based on the SHA-256 hash function [duplicate]

I've come up with this little routine for doing encryption using the SHA-2 (in this case SHA-256) hash function. As such it is a block cipher with a 256 bit (32 byte) block size and an arbitrary key ...
user avatar
-1 votes
3 answers

easy definition of pseudorandomness

I'm trying to make some understanding of the Wikipedia definition of a pseudorandom number generator. Can someone explain the intuition behind this definition (how is this describing "seeming ...
Louis's user avatar
  • 9
1 vote
2 answers

When are PRNG used and when are CSPRNG used

I understand that PRNG are Random Number Generators that uses a deterministic algorithm based off of a seed. I also understand that CSRNG are PRNG that are cryptographic-ally safe to use for ...
Finlay Weber's user avatar
10 votes
1 answer

How distinct are the meanings of the terms "CSPRNG," "DRBG" and "stream cipher"?

Are there universal, consensus definitions for the following terms? Cryptographically secure pseudo-random number generator ("CSPRNG") Deterministic random bit generator ("DRBG") Stream cipher This ...
Luis Casillas's user avatar
1 vote
1 answer

I made an encryption device for school how can I make it better? [closed]

(All programmed in Visual Basic) How it works is it gets a random number from 1 to 30000 and changes the first character by it in Unicode then it uses that number to change the first character of the ...
Alex's user avatar
  • 13
1 vote
1 answer

New Cryptographic Algorithm [closed]

I was wondering about an algorithm that would take a bitstring as an input, shuffle it and output it. You could use a deterministic RNG to select pairs of bits to swap, using the seed as some sort of ...
Caius Iulius Caesar's user avatar
1 vote
1 answer

Creating a random password based off of a prime number

So I am making an application that basically creates strings that must be encrypted before they are stored on a user's device. If the user blindly starts running the application without creating a ...
rdadkins's user avatar
  • 113
1 vote
0 answers

Difference between statistical PRNG and cryptographic PRNG? [duplicate]

What's the difference between a statistical pseudorandom number generator (PRNG) and a cryptographic-strength PRNG? I've seen a lot of PRNGs that are proposed for statistical uses -- e.g., ...
D.W.'s user avatar
  • 36.4k