-- On 24 Feb 2005 at 2:29, Peter Gutmann wrote:
Isn't this a Crypto 101 mutual authentication mechanism (or at least a somewhat broken reinvention of such)? If the exchange to prove knowledge of the PW has already been performed, why does A need to send the PW to B in the last step? You either use timestamps to prove freshness or add an extra message to exchange a nonce and then there's no need to send the PW. Also in the above B is acting as an oracle for password-guessing attacks, so you don't send back the decrypted text but a recognisable-by-A encrypted response, or garbage if you can't decrypt it, taking care to take the same time whether you get a valid or invalid message to avoid timing attacks. Blah blah Kerberos blah blah done twenty years ago blah blah a'om bomb blah blah.
(Either this is a really bad idea or the details have been mangled by the Register).
It is a badly bungled implementation of a really old idea. An idea, which however, was never implemented on a large scale, resulting in the mass use of phishing attacks. Mutual authentication and password management should have been designed into SSH/PKI from the beginning, but instead they designed it to rely wholly on everyone registering themselves with a centralized authority, which of course failed. SSH/PKI is dead in the water, and causing a major crisis on internet transactions. Needs fixing - needs to be fixed by implementing cryptographic procedures that are so old that they are in danger of being forgetten. --digsig James A. Donald 6YeGpsZR+nOTh/cGwvITnSR3TdzclVpR0+pr3YYQdkG Dn3N69hcbr+mL/HUTw8OhGtKmD9rHYOMN4NTBkIY 47AOCXrb7e35xm5QBsHbFVr/jfm+XwTUvzdiytKpG