ATM Forum communications & contribution

Francois Audet audet at NORTEL.CA
Thu Jan 22 18:46:36 EST 1998


Hello, Jim!

I summarize below our remarks and questions regarding the ASN.1:
1. The fields "RandomVal" and "ranInt" are defined as unconstrained INTEGERs. Is there a specific reason for that? It is more accurate to define a range for them: for example (0..4294967295) .
2. In the definition below, what is the meaning for SEQUENCE containing NULL field? May be it is just a mistake: SEQUENCE instead of CHOICE?

-- signing algorithm used must select one of these types of parameters
-- needed by receiving end of signature.

Params ::= SEQUENCE {
        null            NULL,   -- no value needed
        ranInt  INTEGER OPTIONAL, -- some integer value
        iv8             IV8 OPTIONAL,   -- 8 octet initialization vector
        ...
}

3.  The NonStandardParameter is locally redefined. Its meaning is a subset of the structure of the same name from H.225.0. Could we use the H.225.0 definition, instead of redefining it once again?
4. ALGORITHM-IDENTIFIER is defined and never used.
5. What is the reason for using the definitions of type "TYPE-IDENTIFIER.&Type" for single type only.
For example:
EncodedGeneralToken ::= TYPE-IDENTIFIER.&Type (ClearToken) -- general usage token
Means
EncodedGeneralToken ::= ClearToken -- general usage token

6. According to X.680, in the definitions of type "(WITH COMPONENTS {...," , it should be stated for each field what constrain is applied to it:

PresenceConstraint  ::= PRESENT | ABSENT | OPTIONAL | empty

"empty" is syntactically right, but doesn't add any meaning in our case.

For example:
The following statement

PwdCertToken ::= ClearToken (WITH COMPONENTS {..., timeStamp, generalID })

doesn't provide any additional information to already defined:

ClearToken              ::= SEQUENCE  -- a `token' may contain multiple value types.
{
        timeStamp               TimeStamp OPTIONAL,
        password                        Password OPTIONAL,
        dhkey                   DHset OPTIONAL,
        challenge               ChallengeString OPTIONAL,
        random                  RandomVal OPTIONAL,
        certificate             TypedCertificate OPTIONAL,
        generalID               Identifier OPTIONAL,
        nonStandard             NonStandardParameter OPTIONAL,
        ...
}

Shouldn't it have been explicitly stated as PRESENT?

7. The two above remarks (5 and 6) apply to H.225.0 as well. Look for:
FastStartToken ::= ClearToken (WITH COMPONENTS {..., timeStamp, dhkey, generalID -- set to 'alias' -- })
EncodedFastStartToken ::= TYPE-IDENTIFIER.&Type (FastStartToken)


Thank you,
Orit Levin
RADVision Inc.                          E Mail: orit at radvision.com
575 Corporate Dr., Suite 420            Tel:    201-529-4300 ext. 230
Mahwah, NJ 07430                        Fax:    201-529-3516



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