Subject: Re: [Fwd: Re: Kerberos Revisions and UTF8]

From: Jeffrey Altman <[email-masked]>
Date: Thu, 9 Aug 2001 11:04:55 EDT

Tom wrote:
> jaltman> I'm not going to say that Microsoft caused this problem
> jaltman> because the reality is that none of us in the working group
> jaltman> were aware of the semantics of "GeneralString", but Microsoft
> jaltman> does appear to have the one and only implementation which is
> jaltman> in violation of the spec.  If by some chance the Microsoft
> jaltman> engineers reading RFC-1510 understood the definition of ASN.1
> jaltman> GeneralString and used the appropriate ISO-2002 escapes we
> jaltman> would not be struggling with this.  We would simply be going
> jaltman> back and fixing all of the other implementations to either
> jaltman> enforce the ASCII restriction (since ASCII does not require
> jaltman> escapes) or add support for UTF-8 with escapes.
> 
> It is my impression that Microsoft's implementation sends unescaped
> UTF-8 tagged as GeneralString.  Of course, even with escape sequences,
> UTF-8 isn't valid in a GeneralString, since it's a separate encoding,
> not a G set.

UTF-8 is not a G set, but ISO-2022 does provide for escapes to
non-ISO-2022 character sets with and without returns.  The is an ISO
database of registered non-ISO-2022 character sets and their escapes.
The escape for use of UTF-8 with return is

  ESC % G

to return back to ISO-2022 the escape is 

  ESC % @

> Keep in mind that the 7-bit piece of UTF-8 is ASCII, so even Microsoft
> implementations are compliant if they don't send any chracters outside
> of ASCII.

That is true.  There is only a problem in parts of the world that use
non-ASCII characters in Windows names for users, realms, and services.

 Jeffrey Altman * Sr.Software Designer      C-Kermit 8.0 Beta available
 The Kermit Project @ Columbia University   includes Secure Telnet and FTP
 http://www.kermit-project.org/             using Kerberos, SRP, and 
 [email-masked]          OpenSSL.  SSH soon to follow.

---

From: Tom Yu <[email-masked]>
Date: 09 Aug 2001 11:12:08 -0400

>>>>> "jaltman" == Jeffrey Altman <[email-masked]> writes:

jaltman> UTF-8 is not a G set, but ISO-2022 does provide for escapes
jaltman> to non-ISO-2022 character sets with and without returns.  The
jaltman> is an ISO database of registered non-ISO-2022 character sets
jaltman> and their escapes.

In X.690, escape sequences not corresponding to those defining the
character string type are not permitted in the encoding.
GeneralString is defined as permitting all G sets and all C sets.
Reading between the lines, no non-ISO-2022 encodings are permitted,
even if the correct escape sequence is encoded.

---Tom

---

From: Nicolas Williams <[email-masked]>
Date: Thu, 9 Aug 2001 11:32:22 -0400

> non-ASCII characters in Windows names for users, realms, and services.

Would a recommendation to existing users of existing implementations to
stick only to ASCII be useful at this point?

Nico
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