Re: [stir] I-D Action: draft-ietf-stir-certificates-13.txt

Russ Housley <housley@vigilsec.com> Wed, 29 March 2017 18:38 UTC

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From: Russ Housley <housley@vigilsec.com>
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Date: Wed, 29 Mar 2017 14:38:05 -0400
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To: Tony Rutkowski <tony@yaanatech.com>
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Subject: Re: [stir] I-D Action: draft-ietf-stir-certificates-13.txt
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Tony:

> TNAuthorizationList ::= SEQUENCE SIZE (1..MAX) OF TNEntry
> 
> TNEntry ::= CHOICE {
> 	spc [0] ServiceProviderCodeList,
> 	range [1] TelephoneNumberRange,
> 	one E164Number
> 	}
> 
> MH>>> Is this a choice of 2 or 3 items?
>              Seems you can't enumerate item number [2]:  one E164Number.

There are 3 items in the CHOICE (spc, range, and one)  The first two are SEQUENCE, so an explicit tag is needed to aid the decoder. The third item is an IA5String.

> ServiceProviderCodeList ::= SEQUENCE SIZE (1..3) OF IA5String
> 
> TelephoneNumberRange ::= SEQUENCE {
> 	start E164Number,
> 	count INTEGER
> 	}
> 
> MH>>> What is the difference between:
> 	Range = TelephoneNumber Range, where
> 		Start is an E164Number, and
> 		Count = 1
>      and
> 	One = E164Number?
>      Two alternate codes means more complex coding.

The IA5String shows the stat of a block of phone numbers, and the count says the number of consecutive telephone numbers. It would be better to require count to be greater than 1.

I suggest:

   count INTEGER (2..MAX)

> E164Number ::= IA5String (SIZE (1..15)) (FROM ("0123456789#*"))
> 
> MH>>>	E164 numbers can be composed only of "0123456789", no?
> 	So, the use of # and * are currently undefined in this ID.
> 	I would assume that:
> 		# would be an ending digit indicating the end of a shorter than 15 digit
> number.
> 		* would be an ending digit wild-card meaning any phone numbers with
> preceding leading digits.
> 	However, that would render the meaning of "One" ambiguous, and
> 		That would provide another way to do Range, which may complicate code.
> 	Also, what would it mean if the # or * appeared at the beginning or middle of
> a digit string?

The WG already had a discussion on the list about whether to include # and *.  I believe this represents the outcome of that discussion.

Russ