Yeah, I understand password auth mechanisms, it seems I missunderstood how CRAM-SHA1 works.
It sounds as if CRAM-SHA1 does not send a derivation of a SHA1 hash of the password and request a valid response from the server replying with a derivation of the same SHA1 hash. What the hell good is this? What service in their right mind would store clear text passwords? What moron at MS thought this up? Why not challenge/response based on the SHA1 hash of the pass vs the clear text password? Do any commercial mail systems store clear text passwords in order to support this? Matt Pavlovich On Wed, 2003-02-19 at 15:39, Brian Candler wrote: > On Wed, Feb 19, 2003 at 02:57:19PM -0600, Matt Pavlovich wrote: > > Does the CRAM-SHA1 process hand a string that the mail server can > > eventually extract a 'normal' SHA1 hash out of? > > > > If so, then it would be trivial to support SHA1 hash compares if the > > password hash is stored as SHA1 in the directory server. Storing clear > > text passwords sucks, legal departments and mgmt frown on it.. > > No, it's a fundamental laws-of-the-universe thing from the irreversibility > of hashes. > > When a user authenticates to a server, either: > > (1) The user sends the password in cleartext over the wire > The server can keep a hash of the password > OR > (2) The user sends a hash derived from the password over the wire > The server needs to have the the cleartext password [or something > equivalent*] to validate it > > Case (1) is normal logins (AUTH LOGIN or PLAIN and normal Unix shadow > files); case (2) is the CRAM-MD5's and CRAM-SHA1's of this world. > > If you want to have your cake and eat it, the best you can do is to take > case (1), but encrypt the entire session. In other words the user sends > their cleartext password to the server, but it is protected against > eavesdropping by TLS. > > [*] "Something equivalent" to a cleartext password means that it might not > actually be the sequence of letters which the user types, but knowledge of > this value is sufficient to authenticate yourself. > > Windows NT domain authentication falls into this category. A hash of your > password text is stored on the server, and it is challenge-response > authentication. However, to participate in this mechanism, all you actually > need is the hash of the password text, you don't need to know what the > person's original password was. Hence if you break into the server and steal > this hash value, you can use it to gain access: this hash value is a > "plaintext password" in its own right. > > Regards, > > Brian. -- Matt Pavlovich <[EMAIL PROTECTED]> Allegiance Telecom, Inc. ------------------------------------------------------- This SF.net email is sponsored by: SlickEdit Inc. Develop an edge. The most comprehensive and flexible code editor you can use. Code faster. C/C++, C#, Java, HTML, XML, many more. FREE 30-Day Trial. www.slickedit.com/sourceforge _______________________________________________ courier-users mailing list [EMAIL PROTECTED] Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
