If I understand this deployment issue correctly, there is a single provisioning server that converts the cleartext to realm-bound hashes that can be distributed to each server
providing a service?If that's the case, manipulating the salt value should prevent the hash on one server
from being used to gain access to another.I cringe at the idea of hashing a realm or username into the password hash. The classic problem with DIGEST-MD5 is that sites must force massive password changes to rename a realm or bring new realms online. Updating a username is
a hassle too (people get married from time to time).As a result, most sites end up storing reversible passwords which defeats the whole
idea of a verifier.My other concern is that if the server that receives the verifier can't be trusted, there is already a problem. Any verifier can be attacked offline and cracking the password is ultimately only
a matter of the utility bill.For this type of distribution style for authentication, I tend to think a password server
or PKI is in order. - Steven On Mar 17, 2008, at 7:35 PM, Nicolas Williams wrote:
On Mon, Mar 17, 2008 at 05:56:44PM -0700, Chris Newman wrote:I am opposed to this suggestion, leaning in the direction of strongly opposed.This is one of the sources of interoperability problems for DIGEST- MD5(client implementers didn't understand what the domain/realm meant). It makes the client UI more complex and thus creates a significantcomplexity barrier (far more significant than any of the crypto algorithmissues).If the domain matters, users can just use an email-style login identifier(e.g., chris.newman@xxxxxxx as my login identifier).This is not about a domain in the username! This is about enrolling in a realm so that many servers in that realm can authenticate the same users but without being able to impersonate those users to any other servers in that realm. Without this feature the only way to do the above is by having theservers authenticate to a realm server, pass through SCRAM messages andthen get the results from the realm server. Not being able to enroll once but authenticate to many servers seems obnoxious. Nico --