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Maniphest T7628

gpg uses "month" as a synonym for 30 days
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Description

Hello,

this was reported Michael Below on the Debian BTS. It still applies to 2.4.7:

today I generated a new key (0xfaaad43b), and I set the expiration date to 24 months. I had expected this to be the same as two years, as it is defined in the calendar. In fact, it is ten days less.

It looks like gpg assumes that one month = 30 days, so a timespan of one month from today, according to gpg, ends not on March 24th, but on March 26th. This is obviously wrong.

GnuPG should use the measure month as defined in the calendar. Alternatively, it could define its own measure, but then it should be named differently.

testit@argenau:~$ date
Sun Apr 27 13:26:44 CEST 2025
testit@argenau:~$ gpg --full-generate-key
[...]
Please specify how long the key should be valid.
         0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years
Key is valid for? (0) 24m
Key expires at Sat Apr 17 13:22:04 2027 CEST

Details

External Link
https://bugs.debian.org/701566
Version
2.4.7

Event Timeline

ametzler1 created this task.Sun, Apr 27, 1:29 PM
• werner closed this task as Wontfix.Sun, Apr 27, 9:19 PM
• werner claimed this task.
• werner added a subscriber: • werner.

The report is correct but it does not make sense to fix it. If you want to use a concrete expiration date just enter the IS date at the prompt; use ? at the prompt for a short description.

• ikloecker added a subscriber: • ikloecker.Mon, May 5, 3:31 PM

By the way, "years" is also "incorrect" once in ~4 years because it uses n*365 days. Werner's advice still applies. Enter an ISO date if you want an exact date. Or use a UI tool like Kleopatra.

• werner added a comment.Mon, May 5, 4:27 PM

And the US administration might even change the definition of a year to, say, 100 months so that potus can rightfully keep his promise that there won't be more election in the foreseeable future ;-)