Issues with H.235

[Bancroft Scott]

On Wed, 8 Sep 1999, Pete Cordell wrote:

> I'm implementing some of the H.235 stuff and have a few concerns.
>
> RandomVal is defined as INTEGER only.  This is not a particularly helpful
> definition as in theory this could be a million bit + integer if needed.
> Not many computers support such types!  In fact, a well known ASN.1 compiler
> maps this to an int which is a signed 32-bit value on our platform.  Is this
> sufficient?  Without further discussion about the range of this value I feel
> there is a potential for interoperability problems.
>
> Perhaps we can say that RandomVal will never be more than 32 bits long, and
> then add a type like RandomSeq as an OCTET STRING for cases when we need a
> longer random value.

I disagree.  That would be a limitation of the tool and should be
corrected by the tool vendor.

Note that if the ASN.1 compiler that you are using supports the
industry-standard compiler directives then you can say:

        --<ASN1.HugeInteger H235-SECURITY-MESSAGES.RandomVal>--

which instructs the ASN.1 compiler to represent RandomVal locally in a
format suitable for holding extremely large integer values of the kind you
have in mind.  The encoding of such values are as specified by the
encoding rules, independent of the local representation.

Such directives were made an industry standard two or three years ago by a
consortium of companies including Sun, IBM, OSS Nokalva, Hewlett Packard,
Ericsson and others, and you can expect up to date compilers to support
them.

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