Linked Questions

30 votes
5 answers

What do I need to configure, to make sure my software uses /dev/urandom?

When setting up a server, what configuration changes do I need to make sure that all of the software uses /dev/urandom instead of /dev/random? Some servers don't have much entropy in the entropy pool ...
D.W.'s user avatar
  • 99.9k
217 votes
4 answers

Is a rand from /dev/urandom secure for a login key?

Lets say I want to create a cookie for a user. Would simply generating a 1024 bit string by using /dev/urandom, and checking if it already exists (looping until I get a unique one) suffice? Should I ...
Incognito's user avatar
  • 5,264
10 votes
3 answers

Is it worth augmenting /dev/random entropy in software?

Modern Linux systems, especially headless virtuals, often have shallow /dev/random entropy pools, which can cause software to block or fail to run (e.g. Tripwire in FIPS mode) While many agree /dev/...
gowenfawr's user avatar
  • 72.9k
10 votes
3 answers

Allowing the public to generate a CSR from your private key

As a hosting provider, I'd like to make the process of generating a certificate for a customer's domain as convenient as possible. I was pondering creating a webpage where anyone could: generate a ...
MikeyB's user avatar
  • 201
6 votes
3 answers

Pseudo Random Generator is not initialized from the (entropy pool)?

The RHEL5 manuals state that /dev/urandom will use the entropy pool until it's exhausted, and then it will resort to a fall-back pseudo-random algorithm, so that it will never block. But when ...
Michael Bloomberg's user avatar
12 votes
2 answers

How is the available entropy in /dev/random calculated (or estimated)?

It seems (to a non-expert) that /dev/random is acclaimed to be useable as a source of pure random data. However, I am curious as to the analysis of the file /dev/random. /dev/random is a collection ...
user avatar
11 votes
2 answers

Can I use hardware random number generation on my computer? Am I already using it?

A lot of computer security depends on encryption: SSL connections, TCP packet sequencing, encrypted files, etc. These depend on random number generation to ensure that attackers can't guess the ...
Nathan Long's user avatar
  • 2,734
4 votes
2 answers

How can I increase /proc/sys/kernel/random/entropy_avail

I have access to genuine random numbers -, for example. I have a number of processes using /dev/random and my value for /proc/sys/kernel/random/entropy_avail is 143, which is pretty low. ...
Peter Brooks's user avatar
3 votes
1 answer

How negative are virtual machines (vms) to /dev/urandom?

I looked at the questions here and here. This then piqued my interest as I've recently been involved with looking into FIPS compliance, and in my vm environment /dev/urandom compliance testing ...
avgvstvs's user avatar
  • 940
2 votes
1 answer

Why is /dev/random so slow on Linux? [duplicate]

If it's true you only need about 128 bits of entropy to fuel enough data forever, why is it that /dev/random is so slow? My system has uptime of 214 days! Is it really only gathering .000000001 bits ...
Blaze's user avatar
  • 374
1 vote
1 answer

Feeding entropy pool with my own data [duplicate]

Let's state that I have a huge bunch of truly unpredictable random data in file "random.bin". The random data has been created outside of my system and has been securely transfered into my ...
Algiz's user avatar
  • 111