A good idea with bad usage: /dev/urandom(insanecoding.blogspot.ca)
insanecoding.blogspot.ca
A good idea with bad usage: /dev/urandom
http://insanecoding.blogspot.ca/2014/05/a-good-idea-with-bad-usage-devurandom.html
3 comments
> Using poor sources of entropy like /dev/urandom on Linux, or worse, gettimeofday(), and using them to generate long-lived keys.
He missed the point, people complained because he claimed urandom was a poor source of entropy. That post is about using urandom securely, and he even shows that he doesn't know the difference between random and urandom.
He missed the point, people complained because he claimed urandom was a poor source of entropy. That post is about using urandom securely, and he even shows that he doesn't know the difference between random and urandom.
I think you missed what he was saying. He phrased it a few different ways in the blog and the comments, the clearest probably being: "(/dev/urandom || gettimeofday()) is a very poor source of entropy".
He was complaining about a particular usage he was seeing in the wild, not random and urandom, as he explicitly says a few times.
He was complaining about a particular usage he was seeing in the wild, not random and urandom, as he explicitly says a few times.
Not wanting to nitpick, but if attacker manages to unlink("/dev/urandom") then you have bigger problems than just not trusting this one file. Nothing application developer can do will make this system more secure.
/dev/random ist not "pretty much raw entropy", it is the exact same output of the kernel's CSPRNG as /dev/urandom is giving out.
See http://www.2uo.de/myths-about-urandom/#structure