Subject: time-stamp-draft-7

From: Joerg Seidel <[email-masked]>
Date: Fri, 28 Apr 2000 09:19:20 +0200

Denis,

maybe the TSTInfo structure has some inconvenience because of the missing tags
now:

time-stamp-draft-7: IMPLIZIT tagging

TSTInfo ::= SEQUENCE  {
	[...]
     tsa                          GeneralName          OPTIONAL,
     extensions                   [0] Extensions       OPTIONAL
}

X.509 IMPLIZIT: Tagging:

      GeneralName ::= CHOICE {
           otherName                       [0]     OtherName,
           rfc822Name                      [1]     IA5String,
           dNSName                         [2]     IA5String,
           x400Address                     [3]     ORAddress,
           directoryName                   [4]     Name,
           ediPartyName                    [5]     EDIPartyName,
           uniformResourceIdentifier       [6]     IA5String,
           iPAddress                       [7]     OCTET STRING,
           registeredID                    [8]     OBJECT IDENTIFIER}

      OtherName ::= SEQUENCE {
           type-id    OBJECT IDENTIFIER,
           value      [0] EXPLICIT ANY DEFINED BY type-id }

   Extensions  ::=  SEQUENCE SIZE (1..MAX) OF Extension

The parser can't ditinguish between the "GeneralName" field and "[0]
Extensions" in case that the GeneralName choice is "[0] OtherName". Since both
OtherName and Extensions are sequences the tag will be encoded identically and
can't be used to distinguish the two optional entries. They could only
distinguished by checking the tag of the content of the sequence. That isn't
very convinient for implementations.

I suggest changing the tagging to:

TSTInfo ::= SEQUENCE  {
    [...]
     tsa                          [0] GeneralName      OPTIONAL,
     extensions                   [1] Extensions       OPTIONAL
}

Jorg

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---

From: Denis Pinkas <[email-masked]>
Date: Fri, 28 Apr 2000 12:10:29 +0200

Joerg,

Thanks for your careful writing. We came form a maximum tagging
version (which was safe) to a minimum one. It is hard to do minimal
tagging by thinking to all the various combinations.

You are right. Thanks for providing a change proposal.

Denis