linux-kernel - Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function

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Message-ID: <CAHmME9pu6No0wqPzPpaBwQR_b+5CXvh0kke7J8ouN=rx4pxMGg@mail.gmail.com>
Date:   Thu, 15 Dec 2016 00:34:30 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Tom Herbert <tom@...bertland.com>, Netdev <netdev@...r.kernel.org>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux Crypto Mailing List <linux-crypto@...r.kernel.org>,
        Jean-Philippe Aumasson <jeanphilippe.aumasson@...il.com>,
        "Daniel J . Bernstein" <djb@...yp.to>,
        Eric Biggers <ebiggers3@...il.com>,
        David Laight <David.Laight@...lab.com>
Subject: Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function

Hey Linus,

On Thu, Dec 15, 2016 at 12:30 AM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> No. The bug is talking about "words" in the first place.
>
> Depending on your background, a "word" can be generally be either 16
> bits or 32 bits (or, in some cases, 18 bits).
>
> In theory, a 64-bit entity can be a "word" too, but pretty much nobody
> uses that. Even architectures that started out with a 64-bit register
> size and never had any smaller historical baggage (eg alpha) tend to
> call 32-bit entities "words".
>
> So 16 bits can be a word, but some people/architectures will call it a
> "half-word".
>
> To make matters even more confusing, a "quadword" is generally always
> 64 bits, regardless of the size of "word".
>
> So please try to avoid the use of "word" entirely. It's too ambiguous,
> and it's not even helpful as a "size of the native register". It's
> almost purely random.
>
> For the kernel, we tend use
>
>  - uX for types that have specific sizes (X being the number of bits)
>
>  - "[unsigned] long" for native register size
>
> But never "word".

The voice of reason. Have a desired name for this function family?

siphash_3u64s
siphash_3u64
siphash_three_u64
siphash_3sixityfourbitintegers

Or does your reasonable dislike of "word" still allow for the use of
dword and qword, so that the current function names of:

siphash_3qwords
siphash_6dwords

are okay?

Jason