Subj : Binkd and TLS
To   : Alan Ianson
From : Michiel van der Vlist
Date : Sat Dec 21 2019 12:34 pm

Hello Alan,

On Tuesday December 17 2019 14:32, you wrote to me:

MV>> "Secure" is meaningless without specifying against WHAT. What
MV>> threats are we securing against?

AI> Any and all.

That is not a realistic goal. One can not effectively defend if one has no idea
about who or what is the threat.

AI> I believe that TLS is an open standard, largely accepted as a secure
AI> mechanism for internet transport today.

That does not mean it is good or not good for the specific needs of Fidonet.

MV>> That does not make it better for use in Fidonet. Fidonet is not
MV>> the InterNet, it just makes use of it.

AI> There are very few dial-up nodes today. The vast majority of traffic
AI> today is carried over the internet. That is unavoidable unless we go
AI> back to dial-up and I don't think that is going to happen.

Sure POTS is on the way out. Fidonet uses the Internet as the main means of
transport. So?

AI>>> and I would like to be secure.

MV>> You keep saying that,

AI> Yes, it is nothing more than that.

Secure without knowledge of the threat is no security.

MV>> In order to move forward, one first has to know which direction
MV>> matches "forward".

AI> The TLS option is a very secure one.

There is no such thing as universal security. I have reason to trust the
electronic key that protects my car against theft. It does not protect against
a thief breaking into my house to steal the key. It also does not protect
against a thief with a row truck.

AI>>> Maybe I said that wrong. How about this. Binkd's CRYPT option is
AI>>> weak (by todays standards).

MV>> In what way is it weak? Has it been cracked?

AI> Yes, many years ago.

In the context of Fidonet or in the context of PkZip?

AI>>> Maybe we should think about using something more up to date,
AI>>> like TLS.

MV>> "More up to date" is not better by definition. With governments
MV>> that keep pushing for backdoors in encryption, "someting more up
MV>> to date" may actually be a step back.

AI> TLS has been developed in the open so no backdoors there.

1) Open source is no absolute guarantee against backdoors or other weaknesses.

2) The weakness need not be in the protocol itself, it could be in the way that
it is used. Thje weakness in my car key is how ell I guard the key. If the key
falls in the wrong hands, it is useless for potection. TLS depends on the
integrity of the authority signing the certificates. If the authority is
compromised, so are the certificates and the security of TLS.This has alreaduy
happened with the Diginotar CA.

The main threat in Fidonet has been a malicious sysop masquarading a trusted
party to gain access to the secure inbound. A properly configured Fidonet
system has the secure inbound protected by a session password. Session
passwords ended the mail bomb. Binkp does not exchange the passwords in clear
text. Plus that there ar packet passwords. TTBOMK this mechanism has been
effective in protecting the secure inbound.

Please note that the normal implementation of TLS (cerificate for the server
only) does not protect against the main threat of Fidonet: someone masquarading
as a trusted party to gain access to the secure inbound.

Nr 2 on the list of threats in Fidonet is snooping on routed netmail. TLS does
not protect against that either. You need end to end encryption on the message
level for that.

So what does TLS in Fidonet protect against? Someone snooping on the stream? I
say there is no protection against a sufficiently motivated agency with
"infinite" resources. Such as a government. And for the rest it does not
matter. There is no financial gain to be expected by snooping on Fidonet. For
99% it is an exercise in futility anyway. 99% of the traffic in Fidonet is
echomail.

Sorry, I see TLS in Fidonet as shooting on a musquito with a canon.


Cheers, Michiel

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