Hi Arthur, Please do not take my e-mails personally... I must say that I thought you might be one of those show offs who pick through peoples e-mails looking for mistakes and then completely mis the point of the e-mail. My appologies if I am mistaken.
I just think you might have misread the post you reacted to. I read it as this: > OK, time for some user education has to happen here. (Feel free to correct me > if this is in any way wrong) NT-Hash is a password encryption technology just > like crypt is a password encryption technology. If you have a clear text > password you can encrypt it and come out with a NT-Hash password, or you could > encrypt it and come out with a crypt password. However, once it is in an > encrypted form it is impossible to compare two different encryption forms to > tell if it is the same password. MD5 and MSCHAP both use hashed passwords which are irriversible. > PEAP / MSCHAPv2 passes the password encrypted with NT-Hash encryption, so it is > impossible to compare it against the crypt > password stored in LDAP. PEAP-MSCHAPV2 however sends the NTHASH over the line (cryptograficly speaking) In MS-CHAPV2 the NTHASH is compared (cryptograficly speaking) to the stored NTHASH in a database (Microsoft SAM for example). > It is also impossible to decrypt the NT-Hash password > back to a clear text password, so the password passed with PEAP / MSCHAPv2 > cannot be used in a LDAP bind either. The NT hashed password cannot be used with normal LDAP bind. > It is possible to use PEAP / MSCHAPv2 > with LDAP, however one must store the NT-Hash password in LDAP. I've had the > same problem with crypts as my password encryption in LDAP. I ended having to > create an extra LDAP attribute for NT-Hash passwords. But by storing the NT hashed password in LDAP and reading it out during authentication it is therefore possible to use PEAP-MSCHAPV2. > Whenever a user now goes > through a password change, the NT-Hash password attribute will also be > populated at the same time the crypt password is changed in LDAP. After you > set this up, make sure to define the attribute in the ldap.attrmap for > NT-Password and it will work great with PEAP / MSCHAPv2. Except that you have to update two entries in your LDAP when doing a password change. What is wrong with that story? Regards, Tom Rixom > -----Original Message----- > From: Artur Hecker [mailto:[EMAIL PROTECTED] > Sent: Thursday, February 26, 2004 11:30 AM > To: [EMAIL PROTECTED] > Subject: Re: PEAP / MSCHAP2 / LDAP > > > hi > > > > I just can't leave it alone.... sorry... > > yes it actually seems to bother you more than i would have > expected, but > well... :-) > > > > You talk about an attacker attacking the NTHASH... > > > > Why did you bring this in? I thought the discussion was about > > PEAP-MSCHAPV2 LDAP compatibility... > > actually, for me it was kind of about clear-text password and > challenge-response systems, but ok. i didn't want to think > about it in > mschap-dimensions only. the attack remark was supposed to > clarify that > mschap didn't essentially change the problem. > > > > PEAP makes sure the attacker can't get at MSCHAPV2 and MSCHAPV2 > > allows the use of an database fill of hashed passwords which > > could be considered safer than clear text... > > > > So why talk about attacking the NTHASH... I don't understand... why? > > i wasn't talking about attacks against NT-HASH and not about PEAP. we > were talking about MS-CHAP (which actually exists without PEAP.) > > i just made the remark that the system as you presented it does not > change much for the discussion of the basics (which we were > leading in > my opinion). once again, for me, the only important point was > that given > one hash function it would be wrong to generally conclude > that you can > store the hashed password and then use the same hash function in the > related challenge response protocol. ok? that is all that counts. > > now, for the database... i agree that you gain the advantage of not > storing the clear text passwords (however probably without any salt). > but that has nothing to do with the equality of hashes etc. > as i said, > "nt-hash" is not equal "hash" in your own post and it still works. > > > > Maybe you were talking about an inside attack, when the NTHASH > > is retreived from LDAP? But again can't SSL be used to > secure the line? > > again, i wasn't talking about PEAP at all. > > > ciao > artur > > > -- > __________________________________________________________ > Artur Hecker http://www.enst.fr/~hecker > Groupe AccÃs et Mobilità / Computer Science and Networks > E N S T Paris ___________________________________________ > > > - > List info/subscribe/unsubscribe? See > http://www.freeradius.org/list/users.html > â²Ø~ì ®&Þþéì ®&ÞIçÚÿ 0~·ž§bºÊ+ƒùb²ßî±êì†Ù
