Re: Random MIME boundary needed? (was: Security findings)

On Tue, Apr 21, 2026 at 09:40:37AM +0200, Werner Koch wrote:
>I see no attack here.  However, mutt_random_bytes is also used to
>construct message ids.  I would suggest to make them less predictable.
>But do not use new crypto algorithms for that.  All systems come with
>proper random number generators these days.  Something like
>
>  /* Create an unpredicable nonce of LENGTH bytes in BUFFER. */
>  void gcry_create_nonce (void *buffer, size_t length);
>
>if you anyway link to Libgcrypt, or use the respective functions from
>the other crypto libs.

Thank you Werner and Greg KH! (I'll just reply to you both here)

Something like gcry_create_nonce() sounds perfect.  Unfortunately we
don't link to Libgcrypt.

Perhaps, as Greg KH suggested we could try checking for getrandom(), and
then arc4random_buf(), and if both are missing I guess fall back to what
we have now?

Some quick searches suggested FreeBSD and OpenBSD switched their arc4
implementation to use ChaCha.

-- 
Kevin J. McCarthy
GPG Fingerprint: 8975 A9B3 3AA3 7910 385C  5308 ADEF 7684 8031 6BDA

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