Horton

Re: storing an explicit nonce

Stephen Frost <sfrost@snowman.net>

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From: Stephen Frost <sfrost@snowman.net>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Bruce Momjian <bruce@momjian.us>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Masahiko Sawada <sawada.mshk@gmail.com>, Tom Kincaid <tomjohnkincaid@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Thomas Munro <thomas.munro@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Masahiko Sawada <masahiko.sawada@2ndquadrant.com>
Date: 2021-05-26T19:47:34Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Rethink method for assigning OIDs to the template0 and postgres DBs.

  2. pg_upgrade: Preserve database OIDs.

  3. pg_upgrade: Preserve relfilenodes and tablespace OIDs.

  4. Fix for new Boolean node

  5. Improve error handling of HMAC computations

  6. Add macro RelationIsPermanent() to report relation permanence

  7. Enhance nbtree index tuple deletion.

Greetings,

* Stephen Frost (sfrost@snowman.net) wrote:
> * Robert Haas (robertmhaas@gmail.com) wrote:
> > Another idea might be - instead of doing nonce++ every time we write
> > the page, do nonce=random(). That's eventually going to repeat a
> > value, but it's extremely likely to take a *super* long time if there
> > are enough bits. A potentially rather large problem, though, is that
> > generating random numbers in large quantities isn't very cheap.
> 
> There's specific discussion about how to choose a nonce in NIST
> publications and using a properly random one that's large enough is
> one accepted approach, though my recollection was that the preference
> was to use an incrementing guaranteed-unique nonce and using a random
> one was more of a "if you can't coordinate using an incrementing one
> then you can do this".  I can try to hunt for the specifics on that
> though.

Disucssion of generating IVs here:

https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38d.pdf

section 8.2 specifically.

Note that 8.3 also discusses subsequent limitations which one should
follow when using a random nonce, to reduce the chances of a collision.

Thanks,

Stephen