Quick Question About Hashing

[xxdalexx]

I realize using md5() and sha1() can eventually be cracked through brute force. So my question is if I were to do something along these lines:

$p1 = md5("password"); 
$p2 = sha1($p1);
$p3 = md5($p2);

Would that make it harder to crack by re-hashing a couple times then just doing it once?

[Weedpacket]

Possibly. Or it might weaken it due to the fact it (a) reduces the hash space an attacker has to search and (b) (slightly perhaps, but I haven't done that analysis) increases the probability of a collision.

Better to use a better algorithm. SHA512, say; until the AHS has been decided upon that one's considered good enough for Unclassified Government documentation.

Better still of course would be to use a password that isn't so easily attacked, but humans aren't very good at coming up with those it seems.

[xxdalexx]

Well after asking this question I've spent about the last 2 hours researching and learning about how all the hashes work and such. The best I could come up with for lazy people to try to crack these are a couple websites that have databases of hashes that I was messing around with. So basicly if i were to do the md5-sha1-md5 idea, someone would have to have the sha1 hash of the md5 hash in their db, plus the sha1 hash of the md5, plus the md5 hash of the original word. But I also guess that just adding a salt would do about the same trick to not be able to successfully search these hash dbs.

Now for the sha512, from what I understand is that its a variant of sha2, to which I also understand isn't supported in php. Now like I said, I only searched around for about 2 hours, so what is the strongest algorithm that php supports?

[Weedpacket]

Well.....if you had followed the link I gave in my post....