Re: Empty IA5String

[Steven Legg <steven.legg@eb2bcom.com>]

Hallvard,

Hallvard B Furuseth wrote:
> [Syntaxes] section 3.3.15 says an IA5 String may be empty.
>
> Why is that, when Directory String and Printable String may not?

The Directory String and Printable String syntaxes derive from syntaxes
in X.520 that have been constrained to have at least one character.
The IA5 String syntax does not have a counterpart in X.520 so it doesn't
need to be constrained for interoperability reasons.

> If anyone knows, maybe a note should be added to explain.
>
>
> [Strprep] section 2 says:
>
>   This process is intended to act upon non-empty character strings.  If
>   the string to prepare is empty, this process is not applied and the
>   assertion is evaluated to Undefined.
>
> Since an IA5 String can be empty, why shouldn't two empty IA5 Strings
> match each other?

Clearly there is an incompatibility. The working group needs to decide whether to
restrict IA5 String to at least one character, or to allow empty strings to
compare true.

Regards,
Steven