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

From Tom Herbert <tom@herbertland.com>
Newsgroups linux.kernel
Subject Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function
Date 2016-12-15 00:20 +0100
Message-ID <sOr06-6CZ-9@gated-at.bofh.it> (permalink)
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On Wed, Dec 14, 2016 at 2:56 PM, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> Hey Tom,
>
> On Wed, Dec 14, 2016 at 10:35 PM, Tom Herbert <tom@herbertland.com> wrote:
>> Those look good, although I would probably just do 1,2,3 words and
>> then have a function that takes n words like jhash. Might want to call
>> these dword to distinguish from 32 bit words in jhash.
>
> So actually jhash_Nwords makes no sense, since it takes dwords
> (32-bits) not words (16-bits). The siphash analog should be called
> siphash24_Nqwords.
>
Yeah, that's a "bug" with jhash function names.

> I think what I'll do is change what I already have to:
> siphash24_1qword
> siphash24_2qword
> siphash24_3qword
> siphash24_4qword
>
> And then add some static inline helpers to assist with smaller u32s
> like ipv4 addresses called:
>
> siphash24_2dword
> siphash24_4dword
> siphash24_6dword
> siphash24_8dword
>
> While we're having something new, might as well call it the right thing.
>
I'm confused, doesn't 2dword == 1qword? Anyway, I think the qword
functions are good enough. If someone needs to hash over some odd
length they can either put them in a structure padded to 64 bits or
call the hash function that takes a byte length.

>
>> Also, what is the significance of "24" in the function and constant
>> names? Can we just drop that and call this siphash?
>
> SipHash is actually a family of PRFs, differentiated by the number of
> SIPROUNDs after each 64-bit input is processed and the number of
> SIPROUNDs at the very end of the function. The best trade-off of speed
> and security for kernel usage is 2 rounds after each 64-bit input and
> 4 rounds at the end of the function. This doesn't fall to any known
> cryptanalysis and it's very fast.

I'd still drop the "24" unless you really think we're going to have
multiple variants coming into the kernel.

Tom

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Thread

[PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 05:10 +0100
  Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-14 12:40 +0100
    Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 14:20 +0100
      Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-14 16:20 +0100
        Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 20:50 +0100
      Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Herbert Xu <herbert@gondor.apana.org.au> - 2016-12-15 09:00 +0100
        Re: [kernel-hardening] Re: [PATCH v2 1/4] siphash: add  cryptographically secure hashtable function Daniel Micay <danielmicay@gmail.com> - 2016-12-15 09:20 +0100
  Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 13:50 +0100
    Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-14 23:10 +0100
      Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 00:40 +0100
        Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 09:40 +0100
      RE: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function David Laight <David.Laight@ACULAB.COM> - 2016-12-15 12:10 +0100
        RE: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function David Laight <David.Laight@ACULAB.COM> - 2016-12-15 13:30 +0100
          Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 14:00 +0100
            RE: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function David Laight <David.Laight@ACULAB.COM> - 2016-12-15 15:00 +0100
              Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 16:00 +0100
                RE: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function David Laight <David.Laight@ACULAB.COM> - 2016-12-15 16:50 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 17:00 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 20:00 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 21:40 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 21:50 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 22:20 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 22:20 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Peter Zijlstra <peterz@infradead.org> - 2016-12-15 23:10 +0100
                Re: [kernel-hardening] Re: [PATCH v2 1/4] siphash: add  cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 22:20 +0100
                Re: [kernel-hardening] Re: [PATCH v2 1/4] siphash: add  cryptographically secure hashtable function Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-15 22:20 +0100
                Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Peter Zijlstra <peterz@infradead.org> - 2016-12-15 22:20 +0100
        Re: [PATCH v2 1/4] siphash: add cryptographically secure hashtable  function Hannes Frederic Sowa <hannes@stressinduktion.org> - 2016-12-15 13:30 +0100
  [PATCH v3 2/3] secure_seq: use siphash24 instead of md5_transform "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 19:50 +0100
    Re: [PATCH v3 2/3] secure_seq: use siphash24 instead of md5_transform kbuild test robot <lkp@intel.com> - 2016-12-14 22:50 +0100
  [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 19:50 +0100
    [PATCH v3 3/3] random: use siphash24 instead of md5 for get_random_int/long "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 19:50 +0100
      Re: [PATCH v3 3/3] random: use siphash24 instead of md5 for  get_random_int/long kbuild test robot <lkp@intel.com> - 2016-12-14 23:00 +0100
      Re: [PATCH v3 3/3] random: use siphash24 instead of md5 for  get_random_int/long kbuild test robot <lkp@intel.com> - 2016-12-14 23:10 +0100
      RE: [PATCH v3 3/3] random: use siphash24 instead of md5 for  get_random_int/long David Laight <David.Laight@ACULAB.COM> - 2016-12-15 11:20 +0100
        Re: [PATCH v3 3/3] random: use siphash24 instead of md5 for get_random_int/long "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 20:00 +0100
    Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function Tom Herbert <tom@herbertland.com> - 2016-12-14 20:20 +0100
      Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 20:40 +0100
        Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 22:00 +0100
          Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function Tom Herbert <tom@herbertland.com> - 2016-12-14 22:40 +0100
            Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 00:00 +0100
              Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 00:20 +0100
                Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable  function Christian Kujau <lists@nerdbynature.de> - 2016-12-18 01:10 +0100
              Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function Tom Herbert <tom@herbertland.com> - 2016-12-15 00:20 +0100
              Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 00:40 +0100
                Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-15 01:30 +0100
                RE: [PATCH v3 1/3] siphash: add cryptographically secure hashtable  function David Laight <David.Laight@ACULAB.COM> - 2016-12-15 11:30 +0100
              Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-15 00:40 +0100
    Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable  function kbuild test robot <lkp@intel.com> - 2016-12-14 22:20 +0100
      Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-14 22:30 +0100
    [PATCH v4 3/4] secure_seq: use siphash instead of md5_transform "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 02:50 +0100
    [PATCH v4 2/4] siphash: add N[qd]word helpers "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 02:50 +0100
    [PATCH v4 4/4] random: use siphash instead of MD5 for get_random_int/long "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 02:50 +0100
    [PATCH v4 1/4] siphash: add cryptographically secure hashtable function "Jason A. Donenfeld" <Jason@zx2c4.com> - 2016-12-15 02:50 +0100

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