[tz] Fwd: Bulletin C number 58

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Sat Jul 27 20:36:56 UTC 2019

On 2019-07-27 08:21, Paul Eggert wrote:
> Thanks, I installed that into the development version on GitHub.
> I see that the updated file has a space at the end of the '#@ 3802291200' line
> that encodes the expiration (2020-06-28 00:00:00 UTC). I assume this was
> inadvertent. It doesn't break tzcode (which ignores that line), but the format
> of the line is not documented anywhere that I can see. I dropped Judah Levine a
> line about this.

leap-seconds.list tail says:

#       the following special comment contains the
#       hash value of the data in this file computed
#       use the secure hash algorithm as specified
#       by FIPS 180-1. See the files in ~/pub/sha for
#       the details of how this hash value is
#       computed. Note that the hash computation
#       ignores comments and whitespace characters
#       in data lines. It includes the NTP values
#       of both the last modification time and the
#       expiration time of the file, but not the
#       white space on those lines.
#       the hash line is also ignored in the
#       computation.
#h      f28827d2 f263b6c3 ec0f19eb a3e0dbf0 97f3fa30

so only the NTP values in the special comments lines and the data lines are
significant: all non-special comments lines may be ignored, as can comments in
data lines, only the digits in the data and special comments lines are
significant for the hash; and only the hex digits in the hash line are
significant for validation.
Strictly speaking, the file should also follow the format and naming documented
for NTP source crypto files, as it is part of and distributed using those
mechanisms, but that is not enforced anywhere.

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

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