There's an OID that seems like it should appear in
http://www.imc.org/ietf-smime/other-smime-oids.asn
It's an OID that's used by Outlook Express to include the
senders preferred encryption key among the bunch of
certificates that are sent in a PKCS7 signedData structure.
The OID is 1.3.6.1.4.1.311.16.4 (seems to be in Microsoft's
arc). It is used as an authenticated attribute; the idea
seems to be the same as SMIMEEncryptionKeyPreference
(OID = 1.2.840.113549.1.9.16.2.11). The syntax is sligtly
different; it "points to" the actual certificate with only
IssuerAndSerialNumber; i.e. no CHOICE; no IMPLICIT tag.
I have no idea whether it's peculiar to Outlook Express
or also used in Outlook or any other details.
For gory details, here's a snippet from (a slightly
modified) Peter Gutmann's dumpasn1:
3829 30 201:g . . . . . . SEQUENCE {
3832 06 9:h . . . . . . . OBJECT IDENTIFIER '1 3 6 1 4 1 311 16 4'
3843 31 187:h . . . . . . . SET {
3846 30 184:i . . . . . . . . SEQUENCE {
3849 30 177:j . . . . . . . . . SEQUENCE {
3852 31 11:k . . . . . . . . . . SET {
3854 30 9:l . . . . . . . . . . . SEQUENCE {
3856 06 3:m . . . . . . . . . . . . OBJECT IDENTIFIER countryName (2 5 4 6)
3861 13 2:m . . . . . . . . . . . . PrintableString 'US'
:l . . . . . . . . . . . }
:k . . . . . . . . . . }
3865 31 18:k . . . . . . . . . . SET {
3867 30 16:l . . . . . . . . . . . SEQUENCE {
3869 06 3:m . . . . . . . . . . . . OBJECT IDENTIFIER
: . . . . . . . . . . . . . stateOrProvinceName (2 5 4 8)
3874 13 9:m . . . . . . . . . . . . PrintableString 'Wisconsin'
:l . . . . . . . . . . . }
:k . . . . . . . . . . }
3885 31 16:k . . . . . . . . . . SET {
3887 30 14:l . . . . . . . . . . . SEQUENCE {
3889 06 3:m . . . . . . . . . . . . OBJECT IDENTIFIER localityName (2 5 4 7)
3894 13 7:m . . . . . . . . . . . . PrintableString 'Madison'
:l . . . . . . . . . . . }
:k . . . . . . . . . . }
3903 31 32:k . . . . . . . . . . SET {
3905 30 30:l . . . . . . . . . . . SEQUENCE {
3907 06 3:m . . . . . . . . . . . . OBJECT IDENTIFIER
: . . . . . . . . . . . . . organizationName (2 5 4 10)
3912 13 23:m . . . . . . . . . . . . PrintableString 'University of Wisconsin'
:l . . . . . . . . . . . }
:k . . . . . . . . . . }
3937 31 43:k . . . . . . . . . . SET {
3939 30 41:l . . . . . . . . . . . SEQUENCE {
3941 06 3:m . . . . . . . . . . . . OBJECT IDENTIFIER
: . . . . . . . . . . . . . organizationalUnitName (2 5 4 11)
3946 13 34:m . . . . . . . . . . . . PrintableString 'Division of Information
Technology'
:l . . . . . . . . . . . }
:k . . . . . . . . . . }
3982 31 45:k . . . . . . . . . . SET {
3984 30 43:l . . . . . . . . . . . SEQUENCE {
3986 06 3:m . . . . . . . . . . . . OBJECT IDENTIFIER commonName (2 5 4 3)
3991 13 36:m . . . . . . . . . . . . PrintableString 'UW Certificate Services
-- 20000529A'
:l . . . . . . . . . . . }
:k . . . . . . . . . . }
:j . . . . . . . . . }
4029 02 2:j . . . . . . . . . INTEGER 509
:i . . . . . . . . }
:h . . . . . . . }
:g . . . . . . }
Eric Norman
"I like to stand on the shoulders of the giants that
have gone before me. It is the only way I can see
beyond the pile of dung that they left behind."