/dev/random Extremely Slow?

Question

Some background info: I was looking to run a script on a Red Hat server to read some data from /dev/random and use the Perl unpack() command to convert it to a hex string fo

Answer 1

On most Linux systems, /dev/random is powered from actual entropy gathered by the environment. If your system isn't delivering a large amount of data from /dev/random, it likely means that you're not generating enough environmental randomness to power it.

I'm not sure why you think /dev/urandom is "slower" or higher quality. It reuses an internal entropy pool to generate pseudorandomness - making it slightly lower quality - but it doesn't block. Generally, applications that don't require high-level or long-term cryptography can use /dev/urandom reliably.

Try waiting a little while then reading from /dev/urandom again. It's possible that you've exhausted the internal entropy pool reading so much from /dev/random, breaking both generators - allowing your system to create more entropy should replenish them.

See Wikipedia for more info about /dev/random and /dev/urandom.