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Comment by collinmanderson | Hacker News Reader

> We asked MIT whether we could incorporate Kerberos (and other encryption) into the X Window System. According to the advice at the time (and MIT’s lawyers were expert in export control, and later involved in PGP), if we had even incorporated strong crypto for authentication into our sources, this would have put the distribution under export control, and that that would have defeated X’s easy distribution.

Fascinating.

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Did they really have to include strong crypto?

Most secure protocols negotiate a cipher suite. They just had to add the ability to do so, and maybe some placeholder algorithm using the maximum allowed strength at the time.

The flip side is: Just imagine if Kerberos 1.0 with 40-bit DES was baked into X11 or even IPv4. We'd still be fighting those downgrade attacks. Or maybe we'd be layering real encryption over the broken-but-unremovable encryption, with all the overhead that entails.

Why do you think that is true? Cipher suite selection and whitelisting is not a new thing--even if plaintext with CRC32 is in the mix--we deal with it successfully enough in TLS and SSH all the time.

“we deal with it successfully enough in TLS and SSH all the time”

Not quite. Downgrade attacks has been a huge problem for TLS.

True enough, but unless there is some way humanity is going to jump immediately to perfect protocols, then then the tradeoff between backwards-compatibility and downgrade attacks was always going to be with us.

The mere lack of any kind of encryption in our basic protocols can be considered the most important "downgrade attack" around since we never are quite sure when something is going to leak out into the huge background of plaintext.

Until the rise of SSL and IPSEC, I don't think it was the case that protocols typically gave you a choice of ciphers. Keep in mind that they're talking about over a decade earlier.

The article says "even calls to functions to use strong authentication/encryption by providing an external library would have made it covered under export control." Would your proposal have been ruled out by this? They seem to have gone to considerable lengths to find a solution.

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