At 4:32 AM 9/21/95 +0200, Laurent Demailly wrote:

You have excellent points in your detailed answer, thank you, but

Thanks. I'm glad to be able to conduct this discussion at a cordial and intelligent level.

If FV was as used as SSL could be, what prevents, to use your terms, someone to get MILLIONS of FV's identifiers and use each one only once, etc ... (imo your figures about SSL and crypto softs risks are over evaluated, so I over evaluate the 'risks' of yours using same assumptions)

I think you still don't get it, Laurent. If you intercept millions of credit cards, you immediately have something very valuable and untraceable. An FV-ID is much less useful than a credit card number, because it only works with email confirmation and only works on the net. And merely intercepting them doesn't get you anything -- you have to be able to answer the confirmation messages, which is much harder to do "en masse" than passively sniffing for things (and possibly then decrypting them). And a scheme that also replies to such messages is far more likely to leave traces by which the criminal is caught. In other words, when you look at the "millions of interceptions" case, the value of doing this is lower for FV, the difficulty of automating it in the large scale is higher, and the risk of detection is higher, as compared with a one-way scheme that transmits credit cards, whether encrypted or not.

There can't be more security by transferring data on the clear compared to an encrypted one... except maybe that people using encryption can often feel overconfident.

Of course there can, if you're not talking about the same data, which we're not. It's much safer to transmit something without high intrinsic value in unencrypted form than to transmit something with high intrinsic value in encrypted form. That's why FV-ID's were designed the way they are -- low intrinsic value, easy to revoke & reissue, etc. By analogy, it is safer to send a weather report unencrypted than to send detailed instructions about nuclear weapons encrypted.

So, as someone pointed out, it is not that much a problem about CC# which are available easily anyway, but in fact, using encrypted communications is the only way to ensure (some) *privacy*, in addition to being a security improvement.

Also not true. A scheme like FV's gives a fairly high privacy level through the use of pseudonyms. Your FV-ID can be traced to you *only* by FV, and we won't hand out that informaton without a court order.

financial insecurity never was a problem as long as it remains under a small %.

This is an amazing statement, Laurent. It's sort of like saying that building a city in the middle of a flood plain isn't a problem as long as there isn't a flood. You can't dismiss even a low-probability disaster if the consequences of the disaster are extremely high. If the SSL bug had been discovered AFTER there were hundreds of millions of credit cards being transmitted via SSL, and if the person who discovered it had criminal intent, the entire global credit card infrastructure really would have been endangered. Personally, I'm always suspicious of any claims to have "fixed the last bug", so I don't see any reason to assume this isn't inevitable in the long run if a scheme like SSL is used.

Anyway, if you have happy customers, good for you... I'd suggest that you'd use "Security through Clarity" as motto ;-)

That's not a bad motto. I'd prefer to describe our system as focusing on practical, comprehensive security rather than chasing the myth of perfect cryptographic security. (For example, we've probably put more effort into making our server secure from breakins than just about any other site on the Internet.) We're not opposed to cryptography, by the way. There are some obvious places where the use of digital signatures could directly enhance our system, and we're pursuing them. It has also not escaped our notice that, even though we strongly believe that transmitting FV-ID's in the clear is safer than transmitting credit cards encrypted, it would be safer STILL to transmitthe FV-ID's encrypted -- sort of the best of both worlds. And you can count on our doing that when there is a good Internet infrastructure for doing so, which we don't yet believe to be the case. -- Nathaniel