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Message-ID: <734926844.290068.1418455622417.JavaMail.open-xchange@oxuslxltgw11.lxa.perfora.net> Date: Sat, 13 Dec 2014 01:27:02 -0600 (CST) From: Steve Thomas <steve@...tu.com> To: discussions@...sword-hashing.net Subject: Re: [PHC] How important is salting really? > On December 12, 2014 at 11:19 PM Ben Harris <ben@...rr.is> wrote: > > On 13 December 2014 at 11:00, Steve Thomas <steve@...tu.com > <mailto:steve@...tu.com> > wrote: > > > > > P.S. MD5("deliciously-salty-" || pw) is from an infamous article that > > gets salt > > wrong :). It's near the top of Google when searching for rainbow tables. > > > > Joking aside, if you have a unique "deliciously-salty-", truncate the MD5 to > 24 bits, and implement a good rate limiting system you'd probably have a > pretty secure system. Good enough against online attacks, but not so good that > you are giving up someone's password if you leak hashes. [weak passwords are > still weak, and leaks from multiple sources for the same UID would eventually > give up a password] > Huh? Maybe I don't get your sense of humor. You do mean this as a joke, right? Because with IPv6 it's common to get a /48 which gives you 2^16 subnet prefixes (so 2^80 IP addresses if the limit is not per subnet prefix). Just using the subnet prefixes you only need to try 128 passwords per subnet prefix before you are expected to get a collision. Obviously you can buy more servers and/or subnet prefixes. You use to be able to buy a /32 for no reason at all (this would be 1/512 passwords per subnet prefix for a collision). I'm not saying rate limiting is dead because of IPv6. It just severely messes things up.
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