/dev/random and /dev/urandom

[Poul-Henning Kamp]

There is one current concern with MD5: over-ratio of collisions.

What this means is that it may be a bit too easy to find a
MD5 input which generates a given MD5 output.

This has an impact where one uses MD5 in authentication schemes
like:

	server			client
	-----------------------------------------------------------

	WHO ARE YOU ?
	(magic=234287234)
				Calculate MD5(password + 234287234)
				and send the result:
				abd344...

	Calculate MD5(password + 234287234)
	receive clients bid
	compare
	"they are identical, so the client knows the password"
	OK WELCOME!

In such a setting an over-ratio of collisions will at the very least
reduce the probabilities and

In applications where MD5 is simply used as a bit-blender, this is
of no concern.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.