1
vote
2answers
414 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 ...
27
votes
11answers
6k 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 ...
38
votes
9answers
27k 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?
31
votes
4answers
6k 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?...
17
votes
5answers
5k 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, ...
17
votes
3answers
1k 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 ...
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
775 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?
8
votes
4answers
778 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 ...
4
votes
3answers
1k 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 ...
3
votes
3answers
703 views

If the code to shuffle an array is known, is it possible for the randomized shuffle to stay secure?

I recently was looking at Poker shuffles that were hacked and made to be guessable within a reasonable degree and this was because of the weakness of the shuffles. Is it possible to make a shuffle ...
1
vote
2answers
2k views

How to generate a highly unpredictable random bytes

void vncRandomBytes(unsigned char *bytes) { int i; unsigned int seed = (unsigned int) time(0) + getpid() + rand(); srand(seed); for (i = 0; i < CHALLENGESIZE; i++) { bytes[i] = (unsigned char)...
4
votes
2answers
2k views

/dev/random security holes

I'm doing some reading into the security issues surrounding /dev/random but it's proving to be hard to find good sources of information. Can anybody help? I've asked Google and got a bunch of articles ...
9
votes
2answers
1k views

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 ...
6
votes
3answers
345 views

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/...

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