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From: Stefan Kangas <stefankangas@gmail.com>
To: Paul Eggert <eggert@cs.ucla.edu>
Cc: 58472@debbugs.gnu.org, Matt Armstrong <matt@rfc20.org>
Subject: bug#58472: [PATCH] Make `message-unique-id' less prone to collisions
Date: Fri, 14 Oct 2022 11:22:15 +0200	[thread overview]
Message-ID: <CADwFkm=SeFor7SV2AoV83pHRZyo+d0xesrBLW1BLm8srpFPvtQ@mail.gmail.com> (raw)
In-Reply-To: <caa7d03f-68e4-7c24-80c7-e272c456f733@cs.ucla.edu>

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

> 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.

OK, let's use only random data.

> 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==").

Sounds good to me, but:

The only reference I find to `iv-auto' is in (info "(elisp) Format of
GnuTLS Cryptography Inputs").  The `secure-hash' OBJECT parameter is
documented like this:

    The argument OBJECT should be a buffer or a string.

Is the documentation incomplete?

> As an aside, it's weird that there's no easy way to ask Emacs for an
> N-bit random integer, where the randomness is taken from system entropy.
> Shouldn't we extend Emacs to support that? E.g., (make-string 128
> 'iv-auto) could give you an N-byte entropy-derived random string, or
> (random -N) could give you an N-bit entropy-derived random nonnegative
> integer, or something like that. Then we could write something like this:
>
>    (base64-encode-string (make-string 16 'iv-auto))
>
> to get a Message-ID component with 16 bytes (128 bits) of entropy.

Yes, we should find a better interface here.

We also have `cl-random', which I think support float values.  Perhaps
`random' should do the same?  (See also Bug#9103.)

Oh, and whatever we do, we should probably also document it in `(elisp)
Random Numbers'.





  reply	other threads:[~2022-10-14  9:22 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 [this message]
2022-10-16  7:32         ` Stefan Kangas
2022-10-16 17:05           ` Stefan Kangas
2022-10-16 15:19       ` Matt Armstrong
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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