Date: Tue, 11 Jun 2013 18:56:19 -0400 From: Yaniv Sapir <yaniv@...pteva.com> To: john-dev@...ts.openwall.com Subject: Re: Parallella: scrypt Hi Rafa, Looking forward to helping with this. When you get to the Epiphany/Parallella programming part, don't hesitate to email if you have a question. Yaniv. On Tue, Jun 11, 2013 at 6:53 PM, Rafael Waldo Delgado Doblas < lord.rafa@...il.com> wrote: > Hello, > > I will do the first task that you told me, implement scrypt in host mode. > I would like to have a road map for the milestones. Also I would like to > confirm if the milestones are: > > For the first half of the summer: > First, implement scrypt in host mode. > Second, experiment with scrypt time-memory tradeoff. > Third, move it to epiphany. > > For the second half of the summer(early August or maybe before?) : > Fourth, implement epiphany based Litecoin mining. > Fifth, implement descrypt on Parallella. > > Furthermore, I need more information about descrypt. > > Best regards, > Rafa > > > 2013/6/11 Solar Designer <solar@...nwall.com> > >> Rafael - >> >> I notice that you have edited the project description as we had >> discussed off-list: >> >> http://www.google-melange.com/gsoc/project/google/gsoc2013/lordrafa/22001 >> >> It now says "In this project I will add Epiphany support to scrypt code >> using a Parallella board." >> >> This is OK, although I hope you will have time to do more than just that >> during the summer. Further tasks (stretch goals) may include: Litecoin >> mining code both using Epiphany and not, FPGA programming (both for >> scrypt/Litecoin just because we have the Zynq chip anyway, and for other >> JtR "formats" where an FPGA is of more benefit - such as descrypt), >> another/further attempt at using OpenCL to program for Epiphany. >> >> For now, though, let's in fact focus on scrypt. We do not yet have any >> scrypt code in JtR, so your first task is to add such support using the >> host CPU. To do this, please use this encoding syntax: >> >> >> https://www.gitorious.org/scrypt/scrypt-unix-crypt/blobs/master/unix-scrypt.txt >> >> and my revision of Colin Percival's original implementations >> (reference, somewhat optimized, and heavily optimized x86 SSE2 >> intrinsics) as attached to this message (this includes implementation of >> the above encoding syntax as well). >> >> My escrypt includes a defeat_tmto feature. For your project, please >> keep it disabled - that is, set defeat_tmto = 0. This feature is a >> work-in-progress and it's not part of scrypt proper. >> >> (BTW, there's still much room for attack-specific optimization - >> bringing more parallelism down to instruction level - but that's out of >> scope of your project, at least until after you've implemented scrypt on >> Epiphany. I think there's sufficient parallelism in one Salsa20 core to >> fully use Epiphany, and we're limited by the 32 KB of local memory, so >> bringing more parallelism to instruction level is not helpful for >> Epiphany. However, it is likely helpful for modern x86-64 CPUs.) >> >> You need to create a JtR format out of this. Please take a look at >> c3_fmt.c and dummy.c in the JtR tree for some samples. I mention >> c3_fmt.c because it simply uses crypt(3), whereas my escrypt tarball >> provides a similar function. While normally we'd decode the ASCII >> strings back to binary on loading of hashes to crack, and work on the >> binaries then, for scrypt this does not matter much. It's so slow that >> the time wasted on ASCII-encoding will be negligible. c3_fmt.c also >> supports OpenMP with glibc's crypt_r(3), and my escrypt also provides an >> MT-safe function - so you may do things similarly (to include OpenMP >> support too). >> >> Please try to complete this within a week. Then your next task will be >> to experiment with scrypt time-memory tradeoff (still on the host CPU): >> >> http://www.openwall.com/lists/crypt-dev/2013/03/21/1 >> >> and then to bring the actual scrypt computation (making use of TMTO as >> needed) to Epiphany (in a revision of the JtR format - maybe a new >> format name, so that both host and Epiphany versions could be invoked >> from the same build of JtR). >> >> I expect that you will need help with the TMTO - please feel free to ask >> for it when you get to that point. >> >> Frankly, I only expect sort of reasonable performance with very low >> memory settings for scrypt - much like Litecoin's 128 KB (at which the >> increase in computation is only about 2x). Thus, for practical use, the >> JtR/host format is far more important than the JtR/Epiphany format. (We >> generally don't have to use TMTO on host, but we do on Epiphany.) The >> primary reason why we even bother to implement scrypt on Epiphany is for >> Litecoin mining (where we know that scrypt's memory setting is only 128 >> KB, >> which is sort of acceptable for Epiphany). Thus, for the Epiphany part >> of the project to potentially make any practical sense at all, you do >> need to proceed to implementation of Litecoin mining. For the Epiphany >> part of the project to potentially make any practical sense for JtR in >> particular (rather than merely for Litecoin mining, which is not exactly >> a JtR task), you do need to proceed to implementation of other formats >> (beyond scrypt) on Parallella (both chips) - I suggest descrypt (because >> it'd make good use of the FPGA and reasonable use of Epiphany, and also >> because it's not perfect on GPUs yet, unlike e.g. most things >> MD5-based). So please try to allocate half the summer to those highly >> desirable stretch goals. >> >> Please let me know if you have any questions or/and comments. >> >> Thanks, >> >> Alexander >> > > -- =========================================================== Yaniv Sapir Adapteva Inc. 1666 Massachusetts Ave, Suite 14 Lexington, MA 02420 Phone: (781)-328-0513 (x104) Email: yaniv@...pteva.com Web: www.adapteva.com ============================================================ CONFIDENTIALITY NOTICE: This e-mail may contain information that is confidential and proprietary to Adapteva, and Adapteva hereby designates the information in this e-mail as confidential. The information is intended only for the use of the individual or entity named above. 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