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Pluggable transports meeting today (Friday 11th of April 2014)
by George Kadianakis 11 Apr '14

11 Apr '14

Greetings humans, this is an email to remind you that the regular biweekly pluggable transports meeting is going to happen today. Place is the #tor-dev IRC channel in OFTC. Time is 17:00 UTC. Cheers!

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Has there been a security evaluation of the Hola routing software?
by Virgil Griffith 11 Apr '14

11 Apr '14

www.hola.org First impression it looks they aim to do the same things Tor does.

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bulb: a tor relay web status dashboard
by Arlo Breault 09 Apr '14

09 Apr '14

There's not much to it yet, but I thought I'd share. https://github.com/arlolra/bulb Contributions welcome! Arlo

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Proposal 231: Migrating authority RSA1024 identity keys
by Nick Mathewson 08 Apr '14

08 Apr '14

This is a companion proposal to 230. Filename: 231-migrate-authority-rsa1024-ids.txt Title: Migrating authority RSA1024 identity keys Authors: Nick Mathewson Created: 8 April 2014 Target: 0.2.? Status: Draft 1. Intro and motivation We'd like for RSA1024 identity keys to die out entirely. But we may need to migrate authority identity keys before that happens. This is especially important because proposal 220 ("Migrate server identity keys to Ed25519") is not yet implemented, and so server identity keys are not kept offline. So when an OpenSSL bug like CVE-2014-0160 makes memory-reading attacks a threat to identity keys, we need a way for authorities to migrate ASAP. Migrating authority ID keys is a trickier problem than migrating router ID keys, since the authority RSA1024 keys are hardwired in the source. We use them to authenticate encrypted OR connections to authorities that we use to publish and retrieve directory information. This proposal does not cover migrating RSA1024 OR identity keys for other nodes; for that, see proposal 230. 2. Design When an authority is using a new RSA1024 key, it retains the old one in a "legacy_link_id_key" file. It uses this key to perform link protocol handshakes at its old address:port, and it uses the new key to perform link protocol handshakes at a new address:port. This should be sufficient for all clients that expect the old address:port:fingerprint to work, while allowing new clients to use the correct address:port:fingerprint. Authorities will sign their own router descriptors with their new identity key, and won't advertise the old port or fingerprint at all in their descriptors. This shouldn't break anything, so far as I know. 3. Implementation We'll have a new flag on an ORPort: "LegacyIDKey". It implies NoAdvertise. If it is present, we use our LegacyIDKey for that ORPort and that ORPort, for all of: * The TLS certificate chains used in the v1 and v2 link protocol handshake. * The certificate chains and declared identity in the v3 link handshake. * Accepting ntor cells. 4. Open questions On ticket #11448, Robert Ransom suggests that authorities may need to publish extra server descriptors for themselves, signed with the old identity key too. We should investigate whether clients will misbehave if they can't find such descriptors. If that's the case, authorities should generate these descriptors, but not include them in votes or the consensus; or if they are included, don't assign them flags that will get them used.

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Request for feedback on public hidden services: shroud
by Alan Shreve 08 Apr '14

08 Apr '14

Hi Tor devs! I’d like your feedback on a new system to provide public hidden services that I call "shroud”. By “public hidden services”, I mean services whose network location cannot be determined (like Tor hidden services) but are accessible by any client on the internet (like hidden services + Tor2Web). I’ve linked to what I think is pretty comprehensive documentation at the end of this message, but here’s a brief summary: Shroud runs over Tor with zero changes to the protocol but *does not* use the Tor hidden service protocol. At a very high level, shroud creates something like a reverse ssh tunnel *over* Tor from a local service to a public proxy. You then point DNS for a domain to the public proxy servers so that internet clients can talk to it. The public proxy servers multiplex TLS connections by inspecting the SNI data and forward the connection through to the appropriate shrouded service over its reverse tunnel. Obviously, shroud makes a number of tradeoffs compared to traditional hidden services and Tor2Web, the most important being: - Shrouded services have real hostname addresses and look just like any “ordinary” web service. - Shrouded services (anecdotally) have better latency characteristics than Tor hidden services - Shrouded services provide no anonymity for clients - Shrouded services are dependent on their public proxy servers being available - Shrouded services rely on DNS and are at the mercy of DNS providers and registrars (excepting things like modifying your /etc/hosts) - Public proxies can not inspect or modify the connections they proxy because they are TLS-encrypted with keys they don’t own Shroud is still very early in development, so I’m looking for feedback from the community on all aspects of the system from overall architecture to UI. In particular, I have a number of questions that I’m researching that I could use guidance on from those of you already steeped in Tor: 1. Shrouded services open up a single long-lived connection TLS connection to their public proxy. Is this a risk that could make it easier to de-anonymize a service? Would it be more difficult for an attacker to locate the service if the service opened a new connection over a new circuit every X seconds? Would it be more difficult for an attacker if the shrouded service communicated with the public proxy over multiple connections over multiple circuits simultaneously? 2. Right now shroud only allows you to tunnel TLS connections on domains you control with the idea that it eases the burden on public proxy operators (namely me). This is kind of akin to having an exit node with a policy that it only allows TLS connections out. Am I worrying too much about the consequences proxying traffic that could be inspected? Allowing non-TLS services would make it *far* easier to set up a shrouded service because a shrouded service provider would 1. not have to own a domain, and 2. not need to create TLS key pairs and acquire certificates. 3. Is this a useful system? I feel like tor2web validates that there are use cases that could benefit from this type of asymmetric anonymity where only the service provider is anonymous, but perhaps someone else can indicate whether this is a path worth pursuing. Links: Source code and documentation: https://github.com/inconshreveable/shroud More in-depth documentation on shroud’s architecture: https://github.com/inconshreveable/shroud/blob/master/docs/ARCHITECTURE.md Pre-built binaries (just for testing/demonstration): Linux: http://dl.shroud.io/linux_386/dev/shroud.zip OS X: http://dl.shroud.io/darwin_amd64/dev/shroud.zip Windows: http://dl.shroud.io/windows_386/dev/shroud.zip Thanks! - alan

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Re: [tor-dev] [RFC] Proposal draft: The move to a single guard node
by Nicholas Hopper 07 Apr '14

07 Apr '14

On Mon, Apr 7, 2014 at 11:34 AM, George Kadianakis > So, based on your response, IIUC, the idea is that because young > guards are underutilized, we want to increase the probability of them > being chosen in non-guard positions, so that they become more utilized > till more people pick them as guards? Right. > Some questions on the terminology you used: > > a) What do you mean by 'last rotation period'? When you say "for > fraction k of the last rotation period", you mean that if the > authorities read consensuses for the past 12 months, and the relay R > was up as a guard for 6 months, then k would be 6/12 == 0.5? The "rotation period" is the average length of time between choosing guards. For example, with the current parameters (IIRC), clients discard a guard and choose a new one at a time uniformly chosen between 30 and 60 days. So the rotation period is 45 days = 45*24 hours = 1080 consensus votes, and essentially in each of those hours, 1/1080 of the clients choose a new guard. So the last rotation period's worth of status documents should be the only ones that matter for figuring out how heavily a node is used as a guard. For example, if a relay has had the guard flag for 15 days (=360 consensus documents) out of the last 45, then that relay has about k=360/1080 of the number of clients using it as a guard as it would have, if it had been a guard for the full 1080 hours. (N.B. I'm making an assumption that guard rotations will be uniformly distributed over the period. This should be safe in equilibrium, but might get kind of shaky when the period first increases to 9 months or whatever the final decision is) > b) By (weight with the guard flag) you mean the result of: > <consensus BW> * <consensus weight> ? > > Is that right, or did I misunderstand you? Yes. > Assuming the above terminology assumptions, I began trying to > understand your formula. First of all, I was wondering how you ended > up with it? Is this some standard form? I'm not very familiar with > these things. Well, the way the weights work is that they compute what fraction of guard bandwidth should be used for middle and exit traffic, assuming that the rest will be all used up by client-guard connections. That is, the weights are telling us to use (1-(<consensus middle weight> + <consensus exit weight>)) fraction of the guard's bandwidth for these connections. But if a relay has only fraction k of its "guard bandwidth" used up this way, then (1-k) of this bandwidth should go back into the pool for other positions. I think that's what the formula does, but I could have it wrong. Does that make sense? -- ------------------------------------------------------------------------ Nicholas Hopper Associate Professor, Computer Science & Engineering, University of Minnesota Visiting Research Director, The Tor Project ------------------------------------------------------------------------

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Some fun build farm docs
by MSvB 07 Apr '14

07 Apr '14

Hi folks, Actually it was suggested that I introduce myself since I'm just getting started so here it is. Since I want to improve third party cookie logic (increase granularity & improve intuitive UI) and remove nasty clipboard temp files left around, I'm starting by getting to know the TBB build process. ...and compiling documentation of irregularities as well as requirements. The requirements will eventually help improve gitian/check-prerequisites.sh in order to automate and avoid long builds ending in failure. That's all to say for now. If you come across a build problem that you think new developers might come across, please add a a comment to ticket #11420 [1]. [1] https://trac.torproject.org/projects/tor/ticket/11420/ Cheers, Michael -- Michael Schloh von Bennewitz Software Development Engineer Europalab Networks R&D, Munich Office: +49(89)44239885 UTC+1 Mobile: Same as 'Office' VoIP: sips:michael@schloh.com Web: http://michael.schloh.com/

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Re: [tor-dev] [RFC] Proposal draft: The move to a single guard node
by Nicholas Hopper 07 Apr '14

07 Apr '14

I think I'll have more to say later, but... On Wed, Mar 26, 2014 at 11:36 AM, George Kadianakis <desnacked(a)riseup.net> wrote: > 1.3. Age of guard as a factor on guard probabilities > > By increasing the guard rotation period we also increase the lack > of clients for young guards since clients will rotate guards even > more infrequently now (see 'Phase three' of [1]). > > We can try to mitigate this phenomenon by giving higher priority to > young guards to be picked as guards: > > To do so, everytime an authority needs to vote for a guard, it > reads a set of consensus documents spanning the past NNN months, and > calculates the age of the guard; that is, in how many consensuses > its public key has been included in the past. > > The authorities include the age of each guard by appending > '[SP "Age=" INT]' in the guard's "w" line. > > When a client picks a guard, it applies the age of each guard as a > weight on its guard probability. XXX unspecified how I'm pretty sure this section has it backwards from what was the intent of the discussion of "guard age" at the dev meeting. The weight factor should be applied when choosing a "new guard" as a middle or exit node, because it is being underutilized as a guard. This makes it straightforward to apply: if relay R has had the guard flag for fraction k of the last rotation period, then its weight for some other position should be k*(weight with the guard flag) + (1-k)*(weight without the guard flag) -- ------------------------------------------------------------------------ Nicholas Hopper Associate Professor, Computer Science & Engineering, University of Minnesota Visiting Research Director, The Tor Project ------------------------------------------------------------------------

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Re: [tor-dev] Stegotorus Challenge - Inheriting from FileStegMod
by vmon＠riseup.net 07 Apr '14

07 Apr '14

Hey Noah, Thanks a lot for the patch. You are doing a great job. I commited your changes here: https://github.com/zackw/stegotorus/commit/a92f977259dd3aaabe9f5812f79bbe73… Please pull the branch f--file-stegize-swf-js-pdf and continue work there. Few comments: 1. Our main point is two get rid of redundant http_handle_client_SWF_receive, http_server_SWF_transmit (you undid deleting them). When you finish moving all modules the following "switch" in http_steg_t::http_client_receive (and in http_steg_t::transmit) will be discarded/disappear: switch(type) { case HTTP_CONTENT_SWF: rval = http_handle_client_SWF_receive(this, conn, dest, source); break; case HTTP_CONTENT_JAVASCRIPT: case HTTP_CONTENT_HTML: rval = http_handle_client_JS_receive(this, conn, dest, source); break; case HTTP_CONTENT_PDF: rval = http_handle_client_PDF_receive(this, conn, dest, source); break; default: log_debug(conn, "receiving a payload of type %i", type); rval = config->file_steg_mods[type]->http_client_receive(conn, dest, source); break; } and we will only need this line (the default case): log_debug(conn, "receiving a payload of type %i", type); rval = config->file_steg_mods[type]->http_client_receive(conn, dest, source); But for now, for any type that you move to FileStegMod structure, you just need to drop the case from this switch, because in new structure it will be taken care of in the default case, (so you don't get those src/steg/http.cc:697:67: error: 'http_handle_client_SWF_receive' was not declared in this scope errors you mentioned). 2. In http.cc, add a line to http_steg_config_t::init_file_steg_mods() to create the SWFSteg: void http_steg_config_t::init_file_steg_mods() { // we can't call this in constructor cause //it should be called after the payload server is initialized //initiating the steg modules //TODO: for now the first modules are set to void till their codes be //transformed into a FileStegMod child file_steg_mods[HTTP_CONTENT_JPEG] = new JPGSteg(payload_server, noise2signal); file_steg_mods[HTTP_CONTENT_PNG] = new PNGSteg(payload_server, noise2signal); file_steg_mods[HTTP_CONTENT_GIF] = new GIFSteg(payload_server, noise2signal); } 3. compare how PayloadScraper::PayloadScraper defines old modules and new modules, and modify for SWFSteg accordingly: _available_file_stegs[HTTP_CONTENT_SWF] = NULL; _available_stegs[2].type = HTTP_CONTENT_SWF; _available_stegs[2].extension = ".swf"; _available_stegs[2].capacity_function = PayloadServer::capacitySWF; vs. _available_file_stegs[HTTP_CONTENT_JPEG] = new JPGSteg(NULL); //We are only using the capacity function so we don't need a payload server _available_stegs[5].type = HTTP_CONTENT_JPEG; _available_stegs[5].extension = ".jpg"; _available_stegs[5].capacity_function = JPGSteg::static_capacity; //Temp measure, later we don't need to do such acrobat Also please look at my comment on the proposal. Bon courage, vmon Noah Rahman <selimthegrim(a)gmail.com> writes: > result of running git format-patch origin/tor-improve --stdout > swfsteg.patch > > On 4/6/14, Noah Rahman <selimthegrim(a)gmail.com> wrote: >> Success! Sending you the patch shortly... >> >> On 4/6/14, Noah Rahman <selimthegrim(a)gmail.com> wrote: >>> attaching new steg files for purely informational purposes, these are >>> the only ones I have modified - my guess is capacitySWF in payload >>> server should remain a stub? It seems like we would want to take the >>> capacity functions out of payload server... >>> >>> >>> >>> On 4/6/14, Noah Rahman <selimthegrim(a)gmail.com> wrote: >>>> Here's my current holdup, I don't think I changed these functions but >>>> will shelve what I have, restore, and do a diff. >>>> >>>> selimthegrim@Rimsky-Korsakoffee:~/stegotorus$ make >>>> make all-am >>>> make[1]: Entering directory `/home/selimthegrim/stegotorus' >>>> depbase=`echo src/steg/http.o | sed 's|[^/]*$|.deps/&|;s|\.o$||'`;\ >>>> g++ -I. -I./src -I./src/steg -I./src/steg/http_steg_mods >>>> -I./src/test/gtest -I./src/test/gtest/include -Wall -Wextra >>>> -Wno-missing-field-initializers -Wformat=2 -std=c++0x -g2 -O0 >>>> -std=gnu++11 -MT src/steg/http.o -MD -MP -MF $depbase.Tpo -c -o >>>> src/steg/http.o src/steg/http.cc &&\ >>>> mv -f $depbase.Tpo $depbase.Po >>>> src/steg/http.cc: In member function 'virtual int >>>> http_steg_t::transmit(evbuffer*)': >>>> src/steg/http.cc:562:75: error: 'http_server_SWF_transmit' was not >>>> declared in this scope >>>> rval = http_server_SWF_transmit(config->payload_server, source, >>>> conn); >>>> >>>> ^ >>>> src/steg/http.cc: In member function 'virtual int >>>> http_steg_t::http_client_receive(evbuffer*, evbuffer*)': >>>> src/steg/http.cc:697:67: error: 'http_handle_client_SWF_receive' was >>>> not declared in this scope >>>> rval = http_handle_client_SWF_receive(this, conn, dest, source); >>>> ^ >>>> make[1]: *** [src/steg/http.o] Error 1 >>>> make[1]: Leaving directory `/home/selimthegrim/stegotorus' >>>> make: *** [all] Error 2 >>>> >>>> >>>> On 4/6/14, Noah Rahman <selimthegrim(a)gmail.com> wrote: >>>>> Ok will use c_HTTP and restore the free block. I did read that text >>>>> file >>>>> and have made appropriate changes >>>>> On Apr 6, 2014 10:49 PM, <vmon(a)riseup.net> wrote: >>>>> >>>>>> Hey Noah, >>>>>> >>>>>> > size_t tmp_len = cover_len * 32; //assert here to prevent overflow >>>>>> This is probably prevented somewhere else, but it is always good to >>>>>> harden the code. >>>>>> >>>>>> > /*if (inf_len < 0 || >>>>>> > out_sz < inf_len - SWF_SAVE_HEADER_LEN - SWF_SAVE_FOOTER_LEN) >>>>>> > { >>>>>> > fprintf(stderr, "inf_len = %d\n", inf_len); >>>>>> > free(tmp_buf); >>>>>> > return -1; >>>>>> > }*/ >>>>>> Why did you get rid of this part? >>>>>> >>>>>> >//how to check max SWF size? c_HTTP_MSG_BUF_SIZE? >>>>>> Sure, there is a confusion between HTTP_MSG_BUF_SIZE and >>>>>> c_HTTP_MSG_BUF_SIZE but we should unite them and use one (the latter >>>>>> is >>>>>> better). >>>>>> >>>>>> > tmp_len= inf_len - SWF_SAVE_HEADER_LEN - SWF_SAVE_FOOTER_LEN; >>>>>> > //reassigned to existing variable >>>>>> > return (ssize_t)tmp_len; //added for new return type >>>>>> sure, you can do >>>>>> >>>>>> return (ssize_t)(inf_len - SWF_SAVE_HEADER_LEN - SWF_SAVE_FOOTER_LEN); >>>>>> >>>>>> But it isn't a big deal. >>>>>> >>>>>> Also please take a look at: >>>>>> >>>>>> >>>>>> doc/writing_new_file_steg_mod_for_http_steg.txt >>>>>> >>>>>> Best of luck, >>>>>> vmon >>>>>> >>>>>> Noah Rahman <selimthegrim(a)gmail.com> writes: >>>>>> >>>>>> > Have finished everything I think I need, trying now to compile a >>>>>> > patch >>>>>> > for SWF. Will start on JS once that is socked away. A few questions >>>>>> > though... (on tmp_len line, and commented out free block) >>>>>> > >>>>>> > ssize_t >>>>>> > SWFSteg::decode(const uint8_t *cover_payload, size_t cover_len, >>>>>> > uint8_t* >>>>>> data) >>>>>> > { >>>>>> > int inf_len; >>>>>> > size_t tmp_len = cover_len * 32; //assert here to prevent overflow >>>>>> > for large covers? >>>>>> > char* tmp_buf = (char *)xmalloc(tmp_len); >>>>>> > >>>>>> > for (;;) { >>>>>> > inf_len = decompress(cover_payload + 8, cover_len - 8, >>>>>> > (uint8_t *)tmp_buf, tmp_len); >>>>>> > if (inf_len != -2) >>>>>> > break; >>>>>> > tmp_len *= 2; >>>>>> > tmp_buf = (char *)xrealloc(tmp_buf, tmp_len); >>>>>> > } >>>>>> > >>>>>> > /*if (inf_len < 0 || >>>>>> > out_sz < inf_len - SWF_SAVE_HEADER_LEN - SWF_SAVE_FOOTER_LEN) >>>>>> > { >>>>>> > fprintf(stderr, "inf_len = %d\n", inf_len); >>>>>> > free(tmp_buf); >>>>>> > return -1; >>>>>> > }*/ //how to check max SWF size? c_HTTP_MSG_BUF_SIZE? >>>>>> > >>>>>> > memcpy(data, tmp_buf + SWF_SAVE_HEADER_LEN, >>>>>> > inf_len - SWF_SAVE_HEADER_LEN - SWF_SAVE_FOOTER_LEN); >>>>>> > tmp_len= inf_len - SWF_SAVE_HEADER_LEN - SWF_SAVE_FOOTER_LEN; >>>>>> > //reassigned to existing variable >>>>>> > return (ssize_t)tmp_len; //added for new return type >>>>>> > } >>>>>> > >>>>>> > On 4/5/14, vmon <vmon(a)riseup.net> wrote: >>>>>> >> >>>>>> >> >>>>>> >> Just make a patch of you changes and email me the patch: >>>>>> >> >>>>>> >> http://ariejan.net/2009/10/26/how-to-create-and-apply-a-patch-with-git/ >>>>>> >> Envoyé depuis un mobile Samsung >>>>>> >> >>>>>> >> -------- Message d'origine -------- >>>>>> >> De : Noah Rahman <selimthegrim(a)gmail.com> >>>>>> >> Date :2014/04/05 19:11 (GMT-05:00) >>>>>> >> À : vmon(a)riseup.net >>>>>> >> Objet : Re: Stegotorus Challenge - Inheriting from FileStegMod >>>>>> >> >>>>>> >> Ok. I'll shoot for SWF and Js by turn and add that to a revised >>>>>> >> proposal for >>>>>> >> the challenge period. I have not heard back from Zack yet. I am in >>>>>> >> UTC+5 now >>>>>> >> so that leaves me all of my Sunday at least? >>>>>> >> >>>>>> >> On Apr 5, 2014 11:02 PM, <vmon(a)riseup.net> wrote: >>>>>> >> Hey Noah, >>>>>> >> >>>>>> >> Just keep in mind that I need to make a recommendation on your >>>>>> >> application by the end of the weekend. >>>>>> >> >>>>>> >> I also like very much if you can add "merging SRI branch of >>>>>> >> Stegotorus" >>>>>> >> to our Stegotorus as well, to the list of the deliverables of the >>>>>> >> proposal. >>>>>> >> >>>>>> >> Thanks, >>>>>> >> vmon >>>>>> >> >>>>>> >> Noah Rahman <selimthegrim(a)gmail.com> writes: >>>>>> >>> Yes, the capacities were a bit of a head scratcher. I'll try swf >>>>>> >>> first >>>>>> >>> and then js. My github ID is baronwolfenstein. >>>>>> >>> >>>>>> >>> Hey Noah, >>>>>> >>> >>>>>> >>> For committing: >>>>>> >>> I think Zack needs to give you write access. Please send your >>>>>> >>> github >>>>>> >>> id >>>>>> >>> to Zack (zackw(a)cmu.edu) and cc me. Once that is done, please >>>>>> >>> branch >>>>>> >>> out >>>>>> >>> of tor-improve and commit. If it takes Zack long to give you >>>>>> >>> permission, >>>>>> >>> you can just fork Zackw/stegotorus of course. Just please only >>>>>> >>> commit >>>>>> >>> compilable code (no syntax error etc), this way it is easier to >>>>>> >>> review >>>>>> >>> the commits. >>>>>> >>> >>>>>> >>> SWF would be easier than JS but if you like the JS it is cool with >>>>>> >>> me. For the swf, basically swf_wrap should go to encode, >>>>>> >>> swf_unwrap >>>>>> >>> to >>>>>> >>> decode and you need basically discard the http_server_SWF_transmit >>>>>> >>> and >>>>>> >>> http_handle_client_SWF_receive functions (these are >>>>>> >>> redundant). Just >>>>>> >>> be >>>>>> >>> careful that what is supposed to be send to each function, is it >>>>>> >>> the >>>>>> >>> payload without header? with header? etc. So just tweak the >>>>>> >>> swf_unwrap/swf_wrap to be compatible with what encode/decode. >>>>>> >>> >>>>>> >>> Capacity functions: >>>>>> >>> Then PayloadServer::capacitySWF should be implemented as >>>>>> >>> swfSteg::capacity. >>>>>> >>> However, You'll find 4 capacity functions and it is probably quite >>>>>> >>> confusing. >>>>>> >>> >>>>>> >>> capacity >>>>>> >>> headless_capacity >>>>>> >>> static_capacity >>>>>> >>> static_headless_capacity >>>>>> >>> >>>>>> >>> static vs virtual: >>>>>> >>> When all the modules are moved to the new model, we'll get rid of >>>>>> >>> static_capacity, static_headless_capacity but till then, we need >>>>>> >>> them >>>>>> >>> to >>>>>> >>> keep this old/new hybrid stegs model. Hence: >>>>>> >>> >>>>>> >>> capacity just calls static_capacity >>>>>> >>> headless_capacity just calls static_headless_capacity >>>>>> >>> >>>>>> >>> headless vs headfull: >>>>>> >>> headless_capcity: computes the capacity when the payload is given >>>>>> >>> without >>>>>> >>> http header (pure file). >>>>>> >>> >>>>>> >>> capacity: compute the capacity when the payload is given as an >>>>>> >>> HTTP >>>>>> >>> response (So it starts with >>>>>> >>> >>>>>> >>> HTTP/1.1 200 OK Server: Apache >>>>>> >>> Accept-Ranges: bytes >>>>>> >>> Content-Type: text/html; charset=utf-8 >>>>>> >>> Content-Length: 920 >>>>>> >>> Connection: keep-alive >>>>>> >>> >>>>>> >>> and then the file starts, so you just need basically to skip the >>>>>> >>> header >>>>>> >>> and call headless_capacity (we probably should implement the >>>>>> >>> capacity >>>>>> >>> in >>>>>> >>> the parent and only make headless_capacity pure virtual). >>>>>> >>> >>>>>> >>> If you take look at: >>>>>> >>> >>>>>> >>> jpgSteg::capacity >>>>>> >>> jpgSteg::headless_capacity >>>>>> >>> jpgSteg::static_capacity >>>>>> >>> jpgSteg::static_headless_capacity >>>>>> >>> >>>>>> >>> all I what say will sound less gibberish to you. >>>>>> >>> >>>>>> >>> Good luck et bon courage, >>>>>> >>> vmon >>>>>> >>> >>>>>> >>> Noah Rahman <selimthegrim(a)gmail.com> writes: >>>>>> >>> >>>>>> >>>> Laying over in Tokyo enroute to bkk, had a look at all the >>>>>> >>>> modules >>>>>> >>> and >>>>>> >>>> will start on the JS one on the plane. I have 24 hours in bkk so >>>>>> >>>> should be able to convert the Js and at least one of the other >>>>>> >>>> ones >>>>>> >>> if >>>>>> >>>> not both to inherit from the FileStegMod by the time I leave >>>>>> >>>> there. >>>>>> >>>> Should I submit the pr to your Tor-improve branch or zackw's? >>>>>> >>>> >>>>>> >> >>>>>> >>>>> >>>> >>> >>

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Re: [tor-dev] Stegotorus Challenge - Inheriting from FileStegMod
by vmon＠riseup.net 06 Apr '14

06 Apr '14

Hey Noah, > size_t tmp_len = cover_len * 32; //assert here to prevent overflow This is probably prevented somewhere else, but it is always good to harden the code. > /*if (inf_len < 0 || > out_sz < inf_len - SWF_SAVE_HEADER_LEN - SWF_SAVE_FOOTER_LEN) { > fprintf(stderr, "inf_len = %d\n", inf_len); > free(tmp_buf); > return -1; > }*/ Why did you get rid of this part? >//how to check max SWF size? c_HTTP_MSG_BUF_SIZE? Sure, there is a confusion between HTTP_MSG_BUF_SIZE and c_HTTP_MSG_BUF_SIZE but we should unite them and use one (the latter is better). > tmp_len= inf_len - SWF_SAVE_HEADER_LEN - SWF_SAVE_FOOTER_LEN; > //reassigned to existing variable > return (ssize_t)tmp_len; //added for new return type sure, you can do return (ssize_t)(inf_len - SWF_SAVE_HEADER_LEN - SWF_SAVE_FOOTER_LEN); But it isn't a big deal. Also please take a look at: doc/writing_new_file_steg_mod_for_http_steg.txt Best of luck, vmon Noah Rahman <selimthegrim(a)gmail.com> writes: > Have finished everything I think I need, trying now to compile a patch > for SWF. Will start on JS once that is socked away. A few questions > though... (on tmp_len line, and commented out free block) > > ssize_t > SWFSteg::decode(const uint8_t *cover_payload, size_t cover_len, uint8_t* data) > { > int inf_len; > size_t tmp_len = cover_len * 32; //assert here to prevent overflow > for large covers? > char* tmp_buf = (char *)xmalloc(tmp_len); > > for (;;) { > inf_len = decompress(cover_payload + 8, cover_len - 8, > (uint8_t *)tmp_buf, tmp_len); > if (inf_len != -2) > break; > tmp_len *= 2; > tmp_buf = (char *)xrealloc(tmp_buf, tmp_len); > } > > /*if (inf_len < 0 || > out_sz < inf_len - SWF_SAVE_HEADER_LEN - SWF_SAVE_FOOTER_LEN) { > fprintf(stderr, "inf_len = %d\n", inf_len); > free(tmp_buf); > return -1; > }*/ //how to check max SWF size? c_HTTP_MSG_BUF_SIZE? > > memcpy(data, tmp_buf + SWF_SAVE_HEADER_LEN, > inf_len - SWF_SAVE_HEADER_LEN - SWF_SAVE_FOOTER_LEN); > tmp_len= inf_len - SWF_SAVE_HEADER_LEN - SWF_SAVE_FOOTER_LEN; > //reassigned to existing variable > return (ssize_t)tmp_len; //added for new return type > } > > On 4/5/14, vmon <vmon(a)riseup.net> wrote: >> >> >> Just make a patch of you changes and email me the patch: >> >> http://ariejan.net/2009/10/26/how-to-create-and-apply-a-patch-with-git/ >> Envoyé depuis un mobile Samsung >> >> -------- Message d'origine -------- >> De : Noah Rahman <selimthegrim(a)gmail.com> >> Date :2014/04/05 19:11 (GMT-05:00) >> À : vmon(a)riseup.net >> Objet : Re: Stegotorus Challenge - Inheriting from FileStegMod >> >> Ok. I'll shoot for SWF and Js by turn and add that to a revised >> proposal for >> the challenge period. I have not heard back from Zack yet. I am in >> UTC+5 now >> so that leaves me all of my Sunday at least? >> >> On Apr 5, 2014 11:02 PM, <vmon(a)riseup.net> wrote: >> Hey Noah, >> >> Just keep in mind that I need to make a recommendation on your >> application by the end of the weekend. >> >> I also like very much if you can add "merging SRI branch of >> Stegotorus" >> to our Stegotorus as well, to the list of the deliverables of the >> proposal. >> >> Thanks, >> vmon >> >> Noah Rahman <selimthegrim(a)gmail.com> writes: >>> Yes, the capacities were a bit of a head scratcher. I'll try swf >>> first >>> and then js. My github ID is baronwolfenstein. >>> >>> Hey Noah, >>> >>> For committing: >>> I think Zack needs to give you write access. Please send your >>> github >>> id >>> to Zack (zackw(a)cmu.edu) and cc me. Once that is done, please branch >>> out >>> of tor-improve and commit. If it takes Zack long to give you >>> permission, >>> you can just fork Zackw/stegotorus of course. Just please only >>> commit >>> compilable code (no syntax error etc), this way it is easier to >>> review >>> the commits. >>> >>> SWF would be easier than JS but if you like the JS it is cool with >>> me. For the swf, basically swf_wrap should go to encode, swf_unwrap >>> to >>> decode and you need basically discard the http_server_SWF_transmit >>> and >>> http_handle_client_SWF_receive functions (these are >>> redundant). Just >>> be >>> careful that what is supposed to be send to each function, is it >>> the >>> payload without header? with header? etc. So just tweak the >>> swf_unwrap/swf_wrap to be compatible with what encode/decode. >>> >>> Capacity functions: >>> Then PayloadServer::capacitySWF should be implemented as >>> swfSteg::capacity. >>> However, You'll find 4 capacity functions and it is probably quite >>> confusing. >>> >>> capacity >>> headless_capacity >>> static_capacity >>> static_headless_capacity >>> >>> static vs virtual: >>> When all the modules are moved to the new model, we'll get rid of >>> static_capacity, static_headless_capacity but till then, we need >>> them >>> to >>> keep this old/new hybrid stegs model. Hence: >>> >>> capacity just calls static_capacity >>> headless_capacity just calls static_headless_capacity >>> >>> headless vs headfull: >>> headless_capcity: computes the capacity when the payload is given >>> without >>> http header (pure file). >>> >>> capacity: compute the capacity when the payload is given as an HTTP >>> response (So it starts with >>> >>> HTTP/1.1 200 OK Server: Apache >>> Accept-Ranges: bytes >>> Content-Type: text/html; charset=utf-8 >>> Content-Length: 920 >>> Connection: keep-alive >>> >>> and then the file starts, so you just need basically to skip the >>> header >>> and call headless_capacity (we probably should implement the >>> capacity >>> in >>> the parent and only make headless_capacity pure virtual). >>> >>> If you take look at: >>> >>> jpgSteg::capacity >>> jpgSteg::headless_capacity >>> jpgSteg::static_capacity >>> jpgSteg::static_headless_capacity >>> >>> all I what say will sound less gibberish to you. >>> >>> Good luck et bon courage, >>> vmon >>> >>> Noah Rahman <selimthegrim(a)gmail.com> writes: >>> >>>> Laying over in Tokyo enroute to bkk, had a look at all the modules >>> and >>>> will start on the JS one on the plane. I have 24 hours in bkk so >>>> should be able to convert the Js and at least one of the other >>>> ones >>> if >>>> not both to inherit from the FileStegMod by the time I leave >>>> there. >>>> Should I submit the pr to your Tor-improve branch or zackw's? >>>> >>

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