[wp-trac] [WordPress Trac] #47186: At least one function in /wp-includes/sodium_compat/src/Core32 times out on 32 bit servers

[WordPress Trac]

#47186: At least one function in /wp-includes/sodium_compat/src/Core32 times out on
32 bit servers
-------------------------------+-------------------------------------------
 Reporter:  lovingboth         |       Owner:  paragoninitiativeenterprises
     Type:  defect (bug)       |      Status:  reviewing
 Priority:  normal             |   Milestone:  5.2.1
Component:  Upgrade/Install    |     Version:  5.2
 Severity:  normal             |  Resolution:
 Keywords:  needs-testing      |     Focuses:
  has-patch                    |
-------------------------------+-------------------------------------------

Comment (by paragoninitiativeenterprises):

 @lovingboth:

 > Or you could use a faster, albeit theoretically slightly less secure,
 algorithm in the first place. Was using SHA512 hashes tested? That's
 native in PHP for all versions WordPress supports.

 SHA512 isn't even in the same universe as Ed25519. See
 https://paragonie.com/blog/2015/08/you-wouldnt-base64-a-password-
 cryptography-decoded for more information. We tried to make the basic
 classifications of cryptographic algorithms easy to understand with that
 article.

 To be explicit:

 * SHA512 is a hash function, that can be almost-trivially used as a
 building block for **symmetric authentication** protocols (i.e. HMAC)
 * Ed25519 is an **asymmetric authentication** digital signature algorithm

 They have completely different security properties. In fact, Ed25519 uses
 SHA512 internally for different steps.

 You can't just replace Ed25519 with the SHA512. That would be like trying
 to build a house with bacon. I like bacon, but I'm not about to trust my
 family's life in its structural integrity.

 @lovingboth:

 > Apologies if this sounds somewhat pointed, but the number of hours I
 have had to spend over this in the last couple of days is not small.

 I understand your frustration. You're not the only one expending hours on
 this problem. It took me a month and a half of almost non-stop development
 to get Curve25519 field arithmetic to work on 32-bit ''at all', and that
 was just the up-front development time.

 I had been taking great efforts over the past year to make it faster, but
 it clearly wasn't adequate.

 @lovingboth:

 > Ah, so it's a known problem with the library that was added to WordPress
 core without, as far as I can see, ever seeing how many WP users are
 running on 32-bit systems.

 It's a known problem that's ''extremely'' challenging to solve, and
 ''almost nobody'' runs PHP in general in production on 32-bit systems
 where they can't ''also'' install PHP extensions via PECL, so it's not one
 that gets a lot of attention.

 In fact, when I raised this issue on Twitter, I had this response:
 https://twitter.com/_francislavoie/status/1126541694617440256

 > Is there actually enough people still on 32bit for that to be worth the
 time?

 Until now, the answer to their question was flatly, "No".

 Most people who run 32-bit PHP have been perfectly content with `pecl
 install sodium` as a solution, to date. I suppose that's the curse of
 early adopters: They tend to be more technical.

 ----

 Anyway! Misunderstandings aside, I'm releasing a new version of
 sodium_compat this evening, which introduces a 9x to 10x speedup when you
 set `ParagonIE_Sodium_Compat::$fastMult = true;` on 32-bit systems.

 https://github.com/paragonie/sodium_compat/pull/86

 For Ed25519 signature verification, we automatically set this
 (temporarily) to `true` since there are no cryptographic secrets that can
 be leaked from integer multiplication in this context.

 In other words: You can anticipate a significant speed-up that won't, in
 this specific context, even theoretically harm security.

 A patch for WordPress will be provided as soon as I'm confident the
 changes are non-breaking and `v1.9.2` is tagged. This will be safe to
 release in `5.2.1`.

 If you'd like to help test this in the meantime, simply copy
 `src/Core32/Int64.php` from the official `v1.9.2` release over the one
 WordPress provides and see if the runtime is acceptable on your machine.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/47186#comment:15>
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