Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-11-12 Thread Michał Górny
W dniu nie, 12.11.2017 o godzinie 21∶22 -0500, użytkownik Joshua Kinard napisał: > On 10/24/2017 00:11, Michał Górny wrote: > > W dniu wto, 24.10.2017 o godzinie 06∶04 +0200, użytkownik Michał Górny > > napisał: > > [snip] > > > > > [BOBO06] is relevant research here, I cited it in the work that

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-11-12 Thread Joshua Kinard
On 11/12/2017 22:48, Gordon Pettey wrote: > On Sun, Nov 12, 2017 at 8:22 PM, Joshua Kinard wrote: > >> Minor clarification, old single core //and// uni-processor. Some older >> machines have multiple physical CPUs that are single-core. Threading >> should be >> okay on these,

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-11-12 Thread Gordon Pettey
On Sun, Nov 12, 2017 at 8:22 PM, Joshua Kinard wrote: > Minor clarification, old single core //and// uni-processor. Some older > machines have multiple physical CPUs that are single-core. Threading > should be > okay on these, as long as the thread count stays under NR_CPUS.

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-11-12 Thread Joshua Kinard
On 10/24/2017 00:11, Michał Górny wrote: > W dniu wto, 24.10.2017 o godzinie 06∶04 +0200, użytkownik Michał Górny > napisał: [snip] >>> [BOBO06] is relevant research here, I cited it in the work that went into >>> GLEP59, the last time we updated the hashes. The less-technical explanation >>>

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-10-24 Thread Allan Wegan
>> That is currently the case with portage, but not an inevitable >> consequence of having 3 hash functions in the Manifest. Portage could >> be made to check only one or two of them (even by default), giving >> the tie-breaking ability to those who need it, and speeding up things >> for those who

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-10-24 Thread Michał Górny
W dniu wto, 24.10.2017 o godzinie 13∶56 +0200, użytkownik Chí-Thanh Christopher Nguyễn napisał: > Michał Górny schrieb: > > Oh, and most notably, the speed loss will be mostly visible to users. > > An attacker would have to compute the additional hashes only > > if the fastest hash already

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-10-24 Thread Rich Freeman
On Tue, Oct 24, 2017 at 4:21 AM, Paweł Hajdan, Jr. wrote: > On 24/10/2017 06:11, Michał Górny wrote: >> W dniu wto, 24.10.2017 o godzinie 06∶04 +0200, użytkownik Michał Górny >> napisał: >>> Three hashes don't give any noticeable advantage. If we want a diverse >>>

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-10-24 Thread Chí-Thanh Christopher Nguyễn
Michał Górny schrieb: > Oh, and most notably, the speed loss will be mostly visible to users. > An attacker would have to compute the additional hashes only > if the fastest hash already matched, i.e. rarely. Users will have to > compute them all the time. That is currently the case with portage,

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-10-24 Thread Paweł Hajdan , Jr .
On 24/10/2017 06:11, Michał Górny wrote: > W dniu wto, 24.10.2017 o godzinie 06∶04 +0200, użytkownik Michał Górny > napisał: >> Three hashes don't give any noticeable advantage. If we want a diverse >> construct, we take SHA3. SHA3 is slower than SHA2 + BLAKE2 combined, so >> even with 3 threaded

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-10-23 Thread Michał Górny
W dniu wto, 24.10.2017 o godzinie 06∶04 +0200, użytkownik Michał Górny napisał: > W dniu pon, 23.10.2017 o godzinie 21∶00 +, użytkownik Robin H. > Johnson napisał: > > On Mon, Oct 23, 2017 at 01:33:15PM +0200, Michał Górny wrote: > > > Dnia 23 października 2017 10:16:38 CEST, "Robin H.

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-10-23 Thread Michał Górny
W dniu pon, 23.10.2017 o godzinie 21∶00 +, użytkownik Robin H. Johnson napisał: > On Mon, Oct 23, 2017 at 01:33:15PM +0200, Michał Górny wrote: > > Dnia 23 października 2017 10:16:38 CEST, "Robin H. Johnson" > > napisał(a): > > > On Fri, Oct 20, 2017 at 05:21:47PM -0500,

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-10-23 Thread Robin H. Johnson
On Mon, Oct 23, 2017 at 01:33:15PM +0200, Michał Górny wrote: > Dnia 23 października 2017 10:16:38 CEST, "Robin H. Johnson" > napisał(a): > >On Fri, Oct 20, 2017 at 05:21:47PM -0500, R0b0t1 wrote: > >> In general I do not mind updating the algorithms used, but I do feel > >>

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-10-23 Thread Michał Górny
Dnia 23 października 2017 10:16:38 CEST, "Robin H. Johnson" napisał(a): >On Fri, Oct 20, 2017 at 05:21:47PM -0500, R0b0t1 wrote: >> In general I do not mind updating the algorithms used, but I do feel >> it is important to keep at least three present. Without at least >three

Re: [gentoo-dev] Manifest2 hashes, take n+1-th: 3 hashes for the tie-breaker case

2017-10-23 Thread Robin H. Johnson
On Fri, Oct 20, 2017 at 05:21:47PM -0500, R0b0t1 wrote: > In general I do not mind updating the algorithms used, but I do feel > it is important to keep at least three present. Without at least three > (or a larger odd number) it is not possible to break a tie. > > That may ultimately be beside