[time-nuts] On the IETF leap-seconds.list SHA1

Anders Wallin anders.e.e.wallin at gmail.com
Thu Dec 21 01:01:51 EST 2017


>
> > For the Paris Observatory and USNO files my program agrees with the SHA1s
> > in the files.
> > For the IETF file there seems to be one byte, a "0" at the start of the
> > third group of 8 hex characters missing.
>
>    This is not a bug but a « feature ». From the ntpd leap hash checking
> code:
>
>  * The NIST code creating the hash writes them out as 5 hex integers
>  * without leading zeros.
>
>    Still, it a little unorthodox and complicates the code.
>

Ha! Thanks for explaining this.
Indeed I find writing out the SHA-1 in groups of 8 characters without
leading zeroes quite surprising and undocumented.
The comments in leap-seconds.list about the SHA-1 refer to a /sha or
/pub/sha folder - is that generic information on the SHA-1 or is there any
inidication of the 8-char/leading-zeroes convention there?
I quickly looked at FIPS-180 but didn't find anything about leading zeros
there.

I am still unable to access the NIST ftp-site linked earlier in this thread.

Anders


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