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From: Matt Armstrong <matt@rfc20.org>
To: Paul Eggert <eggert@cs.ucla.edu>, Stefan Kangas <stefankangas@gmail.com>
Cc: 58472@debbugs.gnu.org
Subject: bug#58472: [PATCH] Make `message-unique-id' less prone to collisions
Date: Sun, 16 Oct 2022 08:19:57 -0700	[thread overview]
Message-ID: <871qr794o2.fsf@rfc20.org> (raw)
In-Reply-To: <caa7d03f-68e4-7c24-80c7-e272c456f733@cs.ucla.edu>

Paul Eggert <eggert@cs.ucla.edu> writes:

> On 2022-10-12 19:46, Stefan Kangas wrote:
>
>> The main goal is to avoid collisions, but using the time also gives an
>> idea of when the message was sent, which is kind of nice.
>
> That info is in the Date: line, along with zillions of other Received: 
> lines. There should be no need to repeat it in the Message-ID line.
>
>> Time also
>> guarantees a somewhat unique value even if the user has happened to set
>> the random seed.
>
> If that's a concern, we should be using more-random data, e.g., with
>
>     (base64-encode-string
>      (secure-hash 'md5 'iv-auto 128 nil t))
>
> if we want 128 bits of randomness (this yields a string like 
> "B8a3usyu5QSE/rTLu0nIHg==").

Small suggestion: `base64-url-encode-string` avoids any trailing `===`
and uses slightly preferable non-alnum chars (I think).

But both can generate Message-Id with "command line switch" chars:
either ?- or ?/.  Since some tools expect users to work directly with
Message-ID at times (https://notmuchmail.org/) it might be nice to avoid
leading non-alnum chars, and possibly avoid '-' to avoid any confusion
with a UUID (in the sense of the schema defined by the RFC standard).

Maybe a base 62 encoder could be written just for this, as Emacs'
version of this doesn't need to be fast.  Can a string be turned into a
non-negative bignum integer in (simple) elisp?

-- 
matt (sent from an Emacs running the feature/noverlay branch)





  parent reply	other threads:[~2022-10-16 15:19 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-12 16:07 bug#58472: [PATCH] Make `message-unique-id' less prone to collisions Stefan Kangas
2022-10-12 18:08 ` Paul Eggert
2022-10-13  2:46   ` Stefan Kangas
2022-10-13  4:53     ` Matt Armstrong
2022-10-13 12:10       ` Stefan Kangas
2022-10-13 16:35         ` Matt Armstrong
2022-10-13 16:38           ` Paul Eggert
2022-10-14  9:22           ` Stefan Kangas
2022-10-13 16:21     ` Paul Eggert
2022-10-14  9:22       ` Stefan Kangas
2022-10-16  7:32         ` Stefan Kangas
2022-10-16 17:05           ` Stefan Kangas
2022-10-16 15:19       ` Matt Armstrong [this message]
2022-10-16 16:49         ` Stefan Kangas
2022-10-17  6:17           ` Matt Armstrong
2022-10-17  7:30           ` Paul Eggert
2022-10-17  8:14             ` Stefan Kangas
2022-10-17  8:23               ` Eli Zaretskii
2022-10-17 18:47               ` Matt Armstrong
2022-10-17  8:16             ` Eli Zaretskii
2022-10-17  8:29               ` Lars Ingebrigtsen
2022-10-17  8:34                 ` Eli Zaretskii
2022-10-17  9:30                 ` Stefan Kangas
2022-10-17 11:22                   ` Lars Ingebrigtsen
2022-10-17 15:40                     ` Stefan Kangas
2022-11-25  1:26                       ` Stefan Kangas
2022-10-17 18:40             ` Matt Armstrong
2022-10-18  1:38               ` Paul Eggert
2022-10-18 14:05                 ` Eli Zaretskii
2022-10-13 11:45 ` Lars Ingebrigtsen
2022-10-13 12:10   ` Stefan Kangas
2022-10-13 19:15     ` Lars Ingebrigtsen

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