[tz] leap-seconds.list format

[brian.inglis at systematicsw.ab.ca]

On 2024-02-10 18:34, Paul Eggert wrote:
> On 2024-02-10 16:22, brian.inglis--- via tz wrote:
>> all we can do for now with the current distribution: using https:// as you 
>> suggested, sha1 check, and eyeball diff (-b) in case of site hacks.

> I guess I'm not following your point because that's clearly not all a user can 
> do. A user can also check the signatures, which are made via a public key 
> certificate. I know a few users do that, because I got email a while back when 
> my public key expired and was renewed.

I was referring solely to the original IERS source files 
leap-seconds.{[0-9]{10,},list} and all we can do for now to validate them, using 
sha1 and eyeball.

We could also check that the new external time stamp file suffix agrees with the 
internal "#$" line update validity NTP time stamp, and that is (normally) in the 
current month January or July, and less than the "#@" line expiry NTP time 
stamp, (normally) eleven months later on 28th June or December, and that date 
agrees with the formatted date in the preceding "expires" comment line.

With known access to the current/previous leap-seconds.list sym-/link or 
.[0-9]{9,} target, we could also check that the update validity time stamp is 
(normally) between the current/previous update validity and expiry time stamps.

-- 
Take care. Thanks, Brian Inglis              Calgary, Alberta, Canada

La perfection est atteinte                   Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter  not when there is no more to add
mais lorsqu'il n'y a plus rien à retirer     but when there is no more to cut
                                 -- Antoine de Saint-Exupéry