Re: Fwd: TLS/SSH bugs

Frederik Kriewitz <[email protected]> writes:

>I'll start with a issue in the SSH server implementation  where we already
>looked at the cryptlib code and are pretty sure that it''s not behaving
>correctly. SSH clients (e.g. OpenSSH >= v6.7) sending DH GEX requests with a
>key size of > 4096 bit won't be able to connect to the server. See
>http://forums.apc.com/message/65463#65463 for details.

That was to deal with a buggy implementation that wanted to use ridiculous key
sizes, effectively the message says "you're trying to connect with a buggy
client".  I wasn't aware that OpenSSH (or at least newer versions) would also
request sizes so strange that they'd be identified as a buggy client.  I'll
update the code to select CRYPT_MAX_PKCSIZE if n > CRYPT_MAX_PKCSIZE and min
<= CRYPT_MAX_PKCSIZE (this is pretty ugly behaviour based on weasel-wording in
the spec, the client doesn't really get what they asked for, but then again
any client asking for a DH group size > 4096 bits is being silly so they
shouldn't expect any better...).

>There seems to be a problem with TLS ClientHello extension handling (breaking
>compatibility with Chrome and Firefox without SSLv3 support):
>http://forums.apc.com/message/65421#65421

That's a somewhat long discussion, I'll have to look at that in more detail.

>Besides that there's an issue with spaces in the common name (I assume that's
>a problem caused by the APC engineers) and certificates using UTF8String data
>types (That might be a general problem). See
>http://forums.apc.com/message/65428#65428

That shouldn't be a cryptlib issue, it just takes whatever you feed it and, as
long as it's identifiable as a usable string type (latin-1, BMP, whatever)
it'll encode it as such.

>Besides that I'm wondering if the SSL/TLS server implementation supports
>sending multiple certificates during the handshake (to support intermediate
>CAs). I briefly looked at the SSL/TLS server Session part of the manual and
>it only talks about a single certificate.

cryptlib sends the entire cert chain, whatever it's given.  The docs talk
about the server certificate, but if there's more there it'll send that as
well.

Peter.

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