Hi,
What is the minimum sum of input lengths len(s1)+len(s2) such that:
- s1, s2 are distinct utf8 strings
- Txt2int(s1) = Txt2int(s2)
for the below simple hash function ?
func Txt2int(s string) uint64 {
x := uint64(len(s))
for i := len(s) - 1; i >= 0; i-- {
x =
There are many measures. One realm of them focus on the mixing properties
of the design as would be a consideration in cypher systems. The other
“experimentalist” realm considers how the hash performs compared to an
ideal hash function.
The latter approach is suitable for a broader range of develo
On Tuesday, February 5, 2019 at 12:29:32 AM UTC+3, Michael Jones wrote:
> I recently did just this in an effort (successful!) to make a well-known
> simple hash function be its best with minor single CPU cycle changes.
>
yes I am told 15 is not the best shift amount, how about this?
x = x<<27 ^
one quick result:
celeste:spin10 mtj$ spin10 -a 0,63 -b 0,63 -bins 32 -rotate ab -set 0,0,0,0
-samples 10 -trials 10
[0] best 5.683527373827505613e+01 8 0 0 0
[1] best 5.508690460484671547e+01 8 1 0 0
[2] best 5.434519430630660253e+01 8 2 0 0
[4] bes
8 Şub 2019 Cum 11:57 tarihinde Michael Jones şunu
yazdı:
> ...says that in one particular test condition (8 character strings, 1M
> random strings, all possible shift values)
> and under one particular metric of virtue...
>
> x = x<<15 ^ x>>33
>
> ...gives the closest overall approximation to a r
clustering:
https://www.cs.cornell.edu/courses/cs3110/2014fa/lectures/13/lec13.html
careful hash functions often treat short inputs specially.
iterated shift-xor alone is weak in expanding the "changed bits(s)" signal,
at least by comparison to a) large prime multiply, b) good s-boxes, c)
introdu
On Fri, Feb 8, 2019 at 7:42 PM Michael Jones wrote:
> clustering:
> https://www.cs.cornell.edu/courses/cs3110/2014fa/lectures/13/lec13.html
>
> careful hash functions often treat short inputs specially.
>
> iterated shift-xor alone is weak in expanding the "changed bits(s)" signal,
> at least by
On Saturday, February 9, 2019 at 5:23:14 PM UTC+3, Serhat Şevki Dinçer
wrote:
>
> On Fri, Feb 8, 2019 at 7:42 PM Michael Jones wrote:
> > clustering:
> > https://www.cs.cornell.edu/courses/cs3110/2014fa/lectures/13/lec13.html
> >
> > careful hash functions often treat short inputs specially.
For more information on hash function goodness tests, check
out https://github.com/demerphq/smhasher
Damian
On Tuesday, February 12, 2019 at 5:23:39 AM UTC-8, Serhat Şevki Dinçer
wrote:
>
> On Saturday, February 9, 2019 at 5:23:14 PM UTC+3, Serhat Şevki Dinçer
> wrote:
>>
>> On Fri, Feb 8, 201
Serhat, some ideas for you...
https://play.golang.org/p/7QPy5wa-9eO
On Tue, Feb 12, 2019 at 9:23 AM Damian Gryski wrote:
> For more information on hash function goodness tests, check out
> https://github.com/demerphq/smhasher
>
> Damian
>
> On Tuesday, February 12, 2019 at 5:23:39 AM UTC-8, Serh
On Tuesday, February 12, 2019 at 9:51:17 PM UTC+3, Michael Jones wrote:
>
> Serhat, some ideas for you...
> https://play.golang.org/p/7QPy5wa-9eO
>
Interestingly I found out input iteration order does matter :) 15,33 shift
version yields an amazing number of collisions (7_910_886_368 collisions
Serhat,
Some more ideas for you to consider: the expected number of collisions for
an ideal random hash, the option of "folding in" the high bits of the hash
rather than truncating, and finer control of operation.
https://play.golang.org/p/92ERC4PJKAL
On Wed, Feb 13, 2019 at 12:20 PM Serhat Şevk
14 Şub 2019 Per 01:58 tarihinde Michael Jones
şunu yazdı:
> Serhat,
>
> Some more ideas for you to consider: the expected number of collisions for
> an ideal random hash, the option of "folding in" the high bits of the hash
> rather than truncating, and finer control of operation.
>
> https://pla
good observations.
here is a help for you... your program modified to do any size computation
in any size of memory
(so you need not look for that special machine)
https://play.golang.org/p/m03mnIP4F0E
On Wed, Feb 13, 2019 at 10:11 PM Serhat Sevki Dincer
wrote:
> 14 Şub 2019 Per 01:58 tarihind
Hi,
Chris kindly searched collisions on his 6 TiB ram server and we could
not find any for more than 5 x 2^37 inputs (for both + and ^ versions)
! Final version of the hash is available at
https://github.com/jfcg/sixb
Let me know if you find one ;)
On Tue, Feb 19, 2019 at 10:44 AM Chris Burkert
15 matches
Mail list logo