July 2012 - tor-dev - lists.torproject.org

[GSoC] Vidalia Report - Week 8
by Feroze Naina 18 Jul '12

18 Jul '12

Last fortnight, I had got the add, remove and edit Hidden Service functionality working. I have been working on fixing a few UI issues - sizing, input sanity check and a browse button for selecting directory. I'm beginning work on the bandwidth scheduling plugin. I've been trying out the ways of doing it through relaybandwidthrate and will be starting on the UI. [1] https://github.com/feroze/vidalia-plugins/commits/hiddenservice

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First-time tails/tor user feedback
by Andrew Lewman 18 Jul '12

18 Jul '12

I spent the past week in Sweden, attending the Stockholm Internet Forum, http://www.stockholminternetforum.se/, for part of it. I made a number of tails 0.10.2 usb sticks for people on request. I also asked a lot of people their impressions of Tor and Tails. I received a plethora of feedback. All 8 people are involved in the Internet Freedom policy, technology, or freedom of speech communities. They had very different levels of self-assessed technical skill. The 8 people represented 6 countries. tldr; 8 people were tested, 8 people had trouble doing simple things with tor browser in Tails. Issues 4-6 are directly related to Tor. And by asked, I mean, I stuck them in front of my laptop, put the usb stick in the computer, and asked them to browse to their favorite site. No one wanted to be video recorded, even if I offered to only record the screen and not audio. Everyone managed to power on the laptop and wait for Tails to boot. # First issue: Language selection The first issue was on the language selection screen. 4 of 8 people were confused why it was called "Debian Live System" and not "Tails Live System". 8 of 8 knew what language selection meant, but weren't sure how this mapped to Tails. # Second issue: wifi and tor browser The tor browser starts up before the wireless is configured. The tor browser then reports a proxy error. With some prompting, all 8 figured out the wifi and then didn't know what to do. Tor does keep trying to load, and takes forever because it needs to download the entire directory. Users have no feedback as to what's going on behind the scenes because vidalia is hidden. 8 of 8 waited patiently for something to happen on the screen. # Third issue: green onion 3 of 8 people saw the green onion appear in the menu bar up top. These three people hovered over it and saw the 'Connected to the Tor Network' message. No one knew to double-click on it to get a menu of other things to do. No one knew to right-click on it to get the drop-down menu. They were presented with the default check.torproject.org 'congratulations' page and then sat there. # Fourth issue: check.tpo is not helpful 8 of 8 people saw the default check.torproject.org site telling them 'congratulations. Your browser is configured to use tor.' 7 of 8 people asked 'where is my browser?' The one who didn't ask this question was already a firefox user and recognized the interface. 0 of 8 understood what the IP address message meant. Comments ranged from 'is that different than my current IP address?' to 'what's an ip address?' As an aside, when showing someone TBB on their own laptop, they saw the check.tpo site, and then went to Safari and started it up. When asked why they did this, the answer was 'safari is my browser. this says your browser is configured to use tor.' No one used the language selections at the bottom of check.tpo, nor even understood why they were there. # Fifth issue: exit relay congestion/failures 8 of 8 people tried to get to their own sites. 'I wonder what my site looks like when I'm anonymous' was the most common comment (5 of 8). For 6 of 8 people, their site didn't load at all, and tor browser reported their site was unreachable. All 6 then tried to go to google search in their own language; meaning google.es, google.se, etc. For 3 of those 6, this didn't work either. They gave up and assumed tor was broken or was censoring their destinations. I intervened, opened the vidalia network map, closed the circuit in question, and asked them to repeat their browsing. 5 of 6 were able to get to their sites now. The one that was not able to had the same exit relay as last time, Amunet1, in a new circuit and just couldn't get anywhere through it. After yet another new circuit, they could get through to everything. The user has no feedback as to why their site didn't work. And tor assumes everything is working fine. When asked "please find a video you like", they all went to youtube. Most of the videos they wanted to see resulted in 'This video is currently unavailable.' 8 of 8 assumed it was because youtube was blocking tor, not because the video is flash-required. 2 of 8 started randomly clicking videos suggested by youtube to see if any of them worked. Eventually, 2 of 8 got videos to work with youtube and were amazed it worked at all. # Sixth issue: no flash, no warning 2 of 8 people had flash apps on their website. 4 of 8 had ad banners that used flash. All were surprised at the red outline with a snake in it appearing instead of their flash apps. None understood what happened. After an explanation, one person suggested changing the red outline with snake to an actual message written inside, along the lines of 'this app blocked for your protection. click here to unblock it.' I explained why that wouldn't work (because there is no flash, java, silverlight plugins installed) and their answer was 'then do not show it at all'. Inside noscript, I unchecked the 'show placeholder..' option and had them browse again. they were happy. It seems if the user cannot do anything about the blocked apps, not showing them may be preferred. # Seventh issue: shutdown I asked all 8 to shutdown tails and let me know when they thought their data was safely no longer on the system. 1 of 8 figured out how to shutdown tails by clicking the big red button in the upper right corner. The rest hit the power button on the laptop. After rebooting, i showed them all they could just pull the usb drive to do it as well. As soon as tails started shutting down, they all assumed everything was safe and tried to power off the laptop. -- Andrew http://tpo.is/contact pgp 0x6B4D6475

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Re: [tor-dev] Ports with hidden/rend services?
by Kevin Evans 17 Jul '12

17 Jul '12

D'oh! I hope this wasn't the wrong place to ask this. I couldn't seem to find anywhere else to ask this.

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Ports with hidden/rend services?
by Kevin Evans 17 Jul '12

17 Jul '12

I am utterly dumbfounded by this (it's probably because I'm really tired), but in rendservice.c in the rend_service_t structure, there is a smartlist_t for the ports. How exactly are the [source and destination] ports stored in there? Thanks, Kevin

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Clarification of prop 186
by Linus Nordberg 17 Jul '12

17 Jul '12

Hi, Can votes and consensuses have more than one "a" line? Prop 186 says, on one hand [...] votes should include a single "a" line for every relay that has an IPv6 address, to include the first IPv6 line in its descriptor. [...] The remaining or-address lines will turn into "a" lines in the microdescriptor. I interpret this to mean that there is at most one "a" line in a status vote or consensus. On the other hand it also says Clients that use microdescriptors should consider a node's addresses to be the address:port listed in the "r" line of a consensus, plus all "a" lines for that node in the consensus, [...] and the vote will include whichever set of "a" lines are given by the most authorities who voted for the descriptor digest that will be used for the router. (Is "vote" a typo? Should it read "consensus"?) This makes me think there can be more than one "a" line in both votes and consensuses. -- Linus

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License for flash proxy software
by David Fifield 16 Jul '12

16 Jul '12

I feel there should be a LICENSE file in the flash proxy client packages currently at http://www.bamsoftware.com/dist/flashproxy/. What is the recommended practice? Right now the files carry no license. I would be happy with anything that is free software and convenient to the Tor Project. For example the 3-clause BSD used by obfsproxy is fine. I am pretty sure that I wrote all the code that is in use at this point. David Fifield

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[GSoc] [Stegotorus] Progress report
by vmon 16 Jul '12

16 Jul '12

Hello everybody, Quick update on the progress of apache payload class for stegotorus: - https://github.com/vmon/payload_scraper/ is working now, checking apache document root dir, find all files usable as payload, compute their capacity and store them in a database. For now, I'm using the database in Stegotorus, but later the whole code is going to be part of Stegotorus and Stegotorus runs it periodically to keep the database updated. - I've written the basic functionality of apache_payload_server class, i.e. get_payload function (and anything else it needs to work). In theory, we should be able to call apache_payload_server::get_payload instead of get_payload, and Stegotorus would request the payload from apache (or as a matter of fact, any http server running on localhost). In practice, it still has compiling error which I'm working on and I expect them to be solved today. - I'm meeting Zack tomorrow to move my codes to his repo, so we have a unified repo from now on. Hopefully, I'll push the apache_payload_server on the new repo. - Afterward, I'm going to incorporate the infranet code http://nms.csail.mit.edu/infranet/ into the apache_payload_server to improve the quality of the steg. That is for now. Cheers, vmon

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[GSoC] Stem stuff - Progress report
by Ravi Chandra Padmala 16 Jul '12

16 Jul '12

Hello. During the last week Damian merged my patches that implement loadconf & saveconf wrapper methods[1][2] in Stem. I am currently working on implementing the router descriptors (from the network status documents). I should have something ready for review by tuesday. Once that is done, I'll work on implementing the microdescriptor parser. I will also be getting my remaining controller class patches merged in parallel. 1. https://gitweb.torproject.org/stem.git/commit/6cc4e195452bc573e34f0b2de295b… 2. https://gitweb.torproject.org/stem.git/commit/e68adb7fdd465e1780bc4ee1243e0… -- neena

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Minimum required ciphers for running Tor as both client and router.
by Gino Badouri 13 Jul '12

13 Jul '12

Hi there, First of all thanks for helping me last time with my mipsel build of Tor with statically linked OpenSSL. It's running fine and we're waiting for the last review of the bandwith-checking scripts before they go live. The second cluster we prepare will consist of low-powered PowerPC devices 250MHz/256MB Ram/8MB Flash. This time Tor will dynamically link to OpenSSL (libcrypto.so.1.0.0 and libssl.so.1.0.0) because there are also other programs depending on it. Because the devices have very limited flash-space the binaries and libraries have to be as small as possible. Tor 0.2.3.19-rc is only 550KB with only libevent staticly linked in (stripped and bz2 compressed). When run, it will be extracted to /tmp, executed and then deleted (since /tmp runs in RAM). It runs very well so far :) However the OpenSSL libraries are quite large for this system and they don't fit in at the moment. libcrypto.so.1.0.0 is 1.9MB and libssl.so.1.0.0 is 375KB (stripped). Our goal is to run Tor both as client and router and therefor I'd like to know the absolute minimum required ciphers for doing so. We've currently compiled OpenSSL 1.0.1 with: NM=powerpc-gnu-nm CC=powerpc-linux-gnu-gcc RANLIB=powerpc-linux-gnu-ranlib AR=powerpc-linux-gnu-ar \ ./Configure --prefix=/home/mastag/root --openssldir=/home/mastag/root/lib/ssl \ shared threads zlib enable-tlsext no-ssl2 no-dso no-idea no-mdc2 no-rc5 \ no-engines no-hw linux-ppc \ >From the OpenSSL documentation it seems that no-hw and no-engines leaves out support for hardware crypto engines so those are safe to set (our devices don't have them). Could anybody provide us with more "no-" options for ciphers we can skip? Thanks alot!

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Re: [tor-dev] Encrypted PM site/hidden service
by Daniel Dennis 13 Jul '12

13 Jul '12

Because I don't have access to phones that may support this I will not try. The code will be open sourced so anyone may port it. But however I will now assume the app may not always be running on an encrypted filesystem so i'll add some support for keeping the files private Anonbox looks cool. It doesnt appear i can write emails? This isn't meant for emails, just simple PMs which you cannot attach image nor need to sign up for. Right now by design i cam PM someone w/o giving them a way to know who i am (although if you want a discussion you should attach your public key) The tech used will be openssl, mono (or .NET) and sqlite. I can drop openssl but i suspect people would prefer using openssl pem keys rather then mono/.NET generated keys. It sounds like you want to know how it works technically. Well, here are some notes i written for myself. It may not make sense or be a little incoherent but perhaps you can get an idea how secure it may be. --What data we have (in the client sqlite db)-- -If app is encrypted, all data unless with a * is encrypted with the symmetric key- db version*, path to pem file*, symmetric key (encrypted with said pem file or generated with PBKDF2 on the users password), misc options, server url, server public key private keys, plain names, ids*, last ident public keys, plain names, ids* association table: association value*, private key id* inbox: private key id*, inmsg/timestamp/optional from public key id outbox: public key id*, outmsg/timestamp/optional reply to public key id draft: same fields as outbox last ident is when the user last identify himself to the server. If user marks server as untrusted this will prevent user from grabbing all his msgs from the server using different keys. This is so the server is less likely to associate a group of keys to one user --- communication to server Handshake with server: Client encrypts random data with server public key, server sends it back plaintext Register public key. Client gives user pub key, server reply's with an encrypted block of random data, client decrypt it using private key then sends it back plaintext Unregister: delete all msgs and public key from user. Of course server sends random data which will need to be sent back as plaintext to verify the key is mine. Send Message: Client send data which is encrypted with AES which key is encrypted with the recipient pub key. The data is msg+optional my reply to/identity pub key) + recipient pub key. This data is compressing with DEFLATE. Server replies with success or error message. It makes sure recipient and your pub key is registered. Also replies with test to ensure the reply-to pub key is yours. Get Messages: Send pubic key i'd like to get messages for. Server sends me random data to send back in plaintext. Then receive all my data (compressed with DEFLATE) Messages is msg + timestamp(UTC server date) + if available the reply to public key. The client app will decrypt the messages and store it either compressed or compressed/encrypted with the db AES key. Timestamp and reply-to pub key are encrypted. Messages are deleted from servers after 10days of retrieval (or immediately). If pub key has not been seen > 1 year he is unregister and all messages are deleted > Date: Thu, 12 Jul 2012 17:12:01 +0000 > From: krugar <tor-admin(a)krugar.de> > To: tor-dev(a)lists.torproject.org > Subject: Re: [tor-dev] Encrypted PM site/hidden service > Message-ID: <4FFF0561.40906(a)krugar.de> > Content-Type: text/plain; charset=ISO-8859-1 > > take a look at https://anonbox.net/ for a similar service. > > a few considerations: if you create an "app" that lives on a mobile > phone, are private keys stored on the phone? are they secured somehow > while the app is running / not running? which public keys will be stored > on the phone? will messages be stored on the phone? > will someone always know who sent a PM, or only if the sender so > chooses? how do you know how to reach someone on your service? are there > pseudonyms? how long to they last? what about key revocation? > what happens if the server is compromised somehow, will attackers be > able to look at the data and see who wrote messages to whom? for which > time period? > > try to clearly define which privacy guarantees you try to achieve > against which type of attacker. the more precise you write this down, > the easier someone can help you spot weaknesses in your concept, and the > better for you and your users once the system is live. > http://dud.inf.tu-dresden.de/Anon_Terminology.shtml may help if you are > uncertain about wording. > > cheers > -k -- http://www.fastmail.fm - Faster than the air-speed velocity of an unladen european swallow

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