Linked Questions

4
votes
2answers
2k views

Why does gpg use /dev/urandom [duplicate]

Looking at the strace output of GPG on my box seems to show that it uses /dev/urandom when encrypting a message without any access to /dev/random even when --no-random-seed-file is specified. Are ...
2
votes
1answer
648 views

Can I use /dev/urandom for generating cryptographic keys? [duplicate]

I need to generate thousands of cryptographic keys. Can I just read the bits from /dev/urandom on a Red Hat system, or do I need to run it through a PRNG? My understanding is that /dev/urandom should ...
0
votes
1answer
185 views

Is /dev/urandom a CSRG? [duplicate]

Can we rely on /dev/urandom on UNIX machines if we need a cryptographically secure random generator?
0
votes
0answers
34 views

What is the difference between /dev/random and /dev/urandom? [duplicate]

Simply put, what are the differences between /dev/random and /dev/urandom from a developer's standpoint? Which one should I use for cryptographic purposes?
51
votes
9answers
48k views

Feeding /dev/random entropy pool?

Which way of additionally feeding /dev/random entropy pool would you suggest for producing random passwords? Or, is there maybe a better way to locally create fully random passwords?
32
votes
11answers
10k 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 ...
43
votes
4answers
16k views

What should be used as a salt?

I always hear that it is best to use salts on top of stored passwords, which then somehow gets concatenated and hashed afterwards. But I don't know what to use as a the salt. What would be a good salt?...
22
votes
5answers
10k views

Java SecureRandom doesn't block? How?

I know from experience that reading from /dev/random blocks when the Linux kernel entropy pool runs out of entropy. Also, I've seen many articles and blog entries stating that when running on Linux, ...
26
votes
2answers
4k views

Is “always use /dev/urandom” still good advice in an age of containers and isolation?

In short: Instead of another question asking about when to use /dev/random instead of /dev/urandom, I present the following scenario, in which I find myself in an application I'm building: A VM or ...
21
votes
3answers
2k views

Why should double submit CSRF tokens be cryptographically strong random numbers?

I was just going through the OWASP's Cheat Sheet for CSRF Prevention. Regarding the double submit cookies method, it says: the site should generate a (cryptographically strong) pseudorandom value ...
10
votes
3answers
2k views

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 ...
9
votes
2answers
1k views

Is a rand from glibc's rand secure for a login key?

Same question as Is a rand from /dev/urandom secure for a login key, but with glibc's rand function instead of /dev/urandom. And what would be a sufficiently secure seed generator?
5
votes
3answers
2k views

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 ...
10
votes
3answers
2k views

How can you securely generate keys on AWS?

Our application needs to generate secure keys for long term storage on AWS using openssl. But I've seen some instance where entropy falls dangerously low on AWS machines and this doesn't appear to be ...
8
votes
4answers
1k views

Hash(master + hostname) password scheme for a server pool

I manage about 20+ Linux servers and I am considering using an md5 scheme similar to following to generate the admin passwords: echo 'masterpassword' 'serverhostname' | md5sum Which returns ...

15 30 50 per page