I'm surprised at this question. We used the word "unpredictable" in RFC 9000 a
few times, with exactly this meaning and had no issue. See for example:
> When an Initial packet is sent by a client that has not previously received
> an Initial or Retry packet from the server, the client populates the
> Destination Connection ID field with an unpredictable value.
Or
> To initiate path validation, an endpoint sends a PATH_CHALLENGE frame
> containing an unpredictable payload on the path to be validated.
Or
Stateless Reset {
Fixed Bits (2) = 1,
Unpredictable Bits (38..),
Stateless Reset Token (128),
}
As you say, a bit can assume one of two values, 0 or 1. Setting a bit to a
predictable value would mean choosing 0 or 1 in a way that someone might be
able to guess the next value. Always 1, always 0, or alternating 0 and 1 are
examples of predictable methods of selecting a value. Setting a bit to an
unpredictable value would mean setting it to either 0 or 1 such that someone
else is unlikely to correctly guess the next value. A random draw is
unpredictable, but there are other methods that would also be unpredictable.
On Thu, Jun 30, 2022, at 22:52, Andrew Alston via Datatracker wrote:
> Andrew Alston has entered the following ballot position for
> draft-ietf-quic-bit-grease-04: Discuss
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> ----------------------------------------------------------------------
> DISCUSS:
> ----------------------------------------------------------------------
>
> Thanks for the work on this document,
>
> Hopefully this discuss will be relatively easy to resolve - and may result
> from
> a lack of understanding - but -
>
> Endpoints that receive the grease_quic_bit transport parameter from a
> peer SHOULD set the QUIC Bit to an unpredictable value unless another
> extension assigns specific meaning to the value of the bit.
>
> Now, this is in reference to a bit - which can only be 0 or 1 - and the
> document further goes on to clarify certain situations where this bit should
> be
> set or unset - so I am not at all sure what this paragraph really means and
> hoping this can be clarified because I'm not sure how this will be interpreted
> on implementation.
