[openssl-project] Help deciding on PR 6341 (facilitate reading PKCS#12 objects in OSSL_STORE)

David Benjamin davidben at google.com
Wed Jun 6 15:23:55 UTC 2018


On Wed, Jun 6, 2018 at 3:45 AM Richard Levitte <levitte at openssl.org> wrote:

> In message <4DCA9A91-1487-4BFC-8A4E-B79FAD473AF3 at dukhovni.org> on Tue, 5
> Jun 2018 18:37:21 -0400, Viktor Dukhovni <openssl-users at dukhovni.org>
> said:
>
> openssl-users>
> openssl-users>
> openssl-users> > On Jun 3, 2018, at 4:45 AM, Richard Levitte <
> levitte at openssl.org> wrote:
> openssl-users> >
> openssl-users> > Yeah, I just learned that myself.  Somehow, I thought
> wchar_t would be
> openssl-users> > Unicode characters.  So ok, with this information, UTF-8
> makes
> openssl-users> > sense...
> openssl-users>
> openssl-users> Nico has convinced me that the mapping from UTF-8 to
> BMPString should
> openssl-users> be UTF-16, which is agrees with the BMP representation on
> the code
> openssl-users> points in the Basic Multinational Plane, but also supports
> surrogate
> openssl-users> pairs for code points outside the plane, so that if someone
> wanted
> openssl-users> to use "emoji" (or more traditional glyph outside the BMP)
> for their
> openssl-users> password, they could.  This is a strict superset of UCS-2
> and avoids
> openssl-users> having to reject some UTF-8 codepoints.
>
> Yup.  It seems that BMPString evolved from UCS-2 into UTF-16 at some
> point, and that evolution affected PKCS#12 objects...
>

Is there a spec citation for this, or some documented experiments against
other implementations' behavior? (What do Microsoft and NSS do here?) I was
pondering something similar recently, but things do seem to point at UCS-2
right now. UCS-2 is indeed an unfortunate historical wart, but X.680 says:

> BMPString is a subtype of UniversalString that has its own unique tag and
contains only the characters in the Basic Multilingual Plane (those
corresponding to the first 64K-2 cells, less cells whose encoding is used
to address characters outside the Basic Multilingual Plane) of ISO/IEC
10646.

RFC 7292 just says to use a BMPString. That doesn't suggest anyone has
actually updated it for UTF-16. This is fine for X.509 where BMPString is
one of many possible string types and folks can use UTF8String for this
anyway. For PKCS#12, yeah, this introduces limitations that may be worth
resolving, UTF-16 being the obvious fix. But if it's not in a spec, we
should get it into one and also be clear on if this is OpenSSL inventing a
behavior or following de facto behavior established elsewhere.
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