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3
votes
0answers
41 views

How does the birthday paradox apply to random keys? [migrated]

I'm developing a web app where I wish to use pseudorandom keys for items, perhaps akin to Imgur. I was thinking about how many combinations I need to reduce the chance of someone guessing any random ...
6
votes
2answers
285 views

How much entropy is good enough for seeding a CSPRNG?

I have some fundamental questions on using Cryptographically Secure Pseudorandom Number Generators (CSPRNGs). What should be the size of the seed that I initialize a CSPRNG with? How often should I ...
5
votes
1answer
42 views

Who can certify RNG according NIST SP800-22?

I have written my own random number generator as a C library and I tested it on NIST Statistical Test Suite. Now I would like to get a certification to have a formal proof that my C library generates ...
6
votes
2answers
559 views

Linux kernel entropy - does it matter to /dev/urandom and what is a minimum?

This question had been asked several times, but still something's not clearly understood from other answers I have a few servers running with a custom built linux kernel (minimal driver modules etc), ...
4
votes
1answer
54 views

Is is possible to avoid internal seeding of a RNG and seed the generator manually using OpenSSL's RAND_bytes()?

I'm trying to write a random number generator with the OpenSSL library. The provided RAND_bytes() function is self-seeding with the /dev/urandom. That's why I am only able to reseed with the ...
4
votes
2answers
106 views

Should other processes be running while an iPhone or Android is generating a cryptographically random number?

I need to generate a cryptographically secure random number on iOS and Android. I could use a software approach or leverage the built in OS API for this. In each case, is it better to generate a ...
5
votes
2answers
99 views

Linux random number compliance

Not sure if this is the right forum, and I am pretty sure that his must have been answered before (I searched a lot but I haven't found a definitive answer). Do the Linux random number generators ...
2
votes
1answer
99 views

Evaluating the Entropy of the PRNG in OpenSSL

I've have a question on the PRNG in OpenSSL. I would like to understand how do you evaluate the diversity/entropy of the PRNG used in the OpenSSL (Cryptographic Library). If this is the wrong ...
0
votes
1answer
55 views

Secure shuffles and the rand() function

I'm trying to understand one aspect of a secure shuffle using Fisher-Yates. For reference, here is Fisher-Yates to shuffle an array x of n elements (numbered from 0 to n-1) (from Securing a Shuffle ...
3
votes
1answer
157 views

Do I need a salt when hashing a randomly generated password?

I have passwords stored in my database that are very long, unique and generated by a CSPRNG. Do I need to use a salt before hashing them? My understanding is that usually you use a hash function in ...
2
votes
2answers
181 views

Securing a Shuffle Algorithm

After reading about writing a secure shuffle algorithm, I realized that my module that generates a password is only as strong as my PRNG, which in this case is Math.random(). I'm confused as to how to ...
3
votes
2answers
179 views

Reliable random seed for RNG

I want to create my computer passwords with a RNG, but I am thinking about one thing: I would use python to write that script and the RNG is controlled by one seed, most likely the time. If I would ...
5
votes
2answers
135 views

Does RNG play a role in PGP signing?

We have a Jenkins system that builds and PGP-signs software releases, and we are considering moving the signing component to an isolated VM instead of running it as part of the overall builder ...
2
votes
3answers
461 views

How secure is to seed PRNGs with the sequences from CSPRNG?

Background: Implementing online casino, I would like to use a number of PRNGs with high throughput, like MersenneTwisterFast. I know it is not cryptographically strong, but quite unpredictable when ...
14
votes
4answers
7k views

Why OpenSSL can't use /dev/random directly?

I couldn't find the answer for the reason anywhere, even the wiki page doesn't explain it. This seems like using a PRNG for seeding an another PRNG. The first one (/dev/random) may itself be seeded by ...
16
votes
3answers
872 views

Why CSRF Token has to be a Cryptographically Strong Random number, in Double Submit Cookies method?

I was just going through the OWASP's Cheat Sheet for CSRF Prevention. In the Double Submit Cookies method, I saw this the site should generate a (cryptographically strong) pseudorandom value ...
0
votes
1answer
482 views

Can SHA-1 PRNG still create secure cipher keys?

I am concerned that a SHA-1 PRNG cannot produce an AES-256 cipher key with the expected 256 bits of security, or indeed any secure cipher key where over 165 bits of security are expected. The SHA-1 ...
2
votes
1answer
562 views

What key to use in HMAC

I need to use HMAC on a certain message to guarantee integrity, but I cannot figure out what are the requirements for the key to be given as input to the hashing algorithm. In particular I have to ...
3
votes
4answers
509 views

What are the features of Dual EC DRBG that are lost when using a different cipher?

Due to a potential NSA backdoor, the NIST is now recommending that implementor no longer use ECC-based PRNG Dual EC DRBG. (As described in Wired.com) this PRNG has certain features such as: ...
9
votes
4answers
1k views

Does hashing a PRNG make it cryptographically secure?

Would hashing the result of a regular random number generator produce a cryptographically secure PRNG? For example, would sha1(rand()) effectively be a secure PRNG? Assuming it doesn't, how would ...
5
votes
1answer
178 views

Detecting PRNG Use from Output

Question: Is there a way to detect the use of a PRNG strictly from observing the output provided by an application? Background: During an audit of a key generating algorithm that I knew was based on ...
3
votes
3answers
351 views

PRNG: Does combining insecure algos help?

Reading about how insecure PHP's rand function is, I was wondering if it helps to combine random functions. The suggested function there, openssl_random_pseudo_bytes, can also be cryptographically ...