Tahoe-LAFS Weekly News, issue number 31, May 19, 2012

Welcome to the Tahoe-LAFS Weekly News (TWN). Tahoe-LAFS is a secure, distributed storage system. View TWN on the web or subscribe to TWN. If you would like to view the "new and improved" TWN, complete with pictures; please take a look.

Announcement and News

Roadmaps Announced

David-Sarah davidsarah announced the roadmaps for 1.9.2, 1.10.0 and 1.11.0.

1.9.2 will be a bugfix release. Its focus will be fixing regressions in mutable file support. Although developers resolved several of the bugs, further testing and review is necessary. 1.9.2 will be released from the darcs branch and will hopefully release at the end of May.

1.10.0 will be released via git. It will include Brian Warner's brian introducer improvements, including Ed25519-signed announcements. This will allow for multiple introducers and accounting. Also this release will see a "move" operation added to the web interface.

1.11.0's features have not been set in stone. However, they may include

  • improvements to share placement to meet the servers-of-happiness criterion in more cases;
  • extending servers-of-happiness to mutable files;
  • some form of accounting;
  • a read-only mode for Tahoe gateways;
  • support for AES+XSalsa encryption, which would remain secure even if a flaw were discovered in either one of its constituent ciphers, including if there were a timing attack against the AES implementation;
  • a 'tahoe mount' command that simplifies mounting a Tahoe filesystem via sshfs;
  • merging the S3 backend support (and possibly other cloud service
  • support) developed by Least Authority Enterprises;
  • extending the drop-upload feature to Windows;
  • merging the patches for Tor and I2P into the main release.

Redundant Array of Independent Clouds

Diego "sickness" Righi sickness created a Redundant Array of Independent Clouds (RAIC). Cloud services while simple and attractive, experience three major issues. One, what happens if they fail and lose your files? Two, how do they prevent someone from gaining unauthorized access to your files? Three, what recourse do you have to your files if the service stops providing access (i.e. bankrupt, government shutdown). Through the use of Tahoe-LAFS, sickness is able to overcome these issues with three large benefits:

"1) My files are encrypted BEFORE being stored on my local disk and BEFORE being sent to the remote cloud provider, so whoever stoles this local workstation or manages to hack the remote cloud servers will not get access to my files 2) I can configure a zfec factor of 3:6 so in the event that 3 cloud providers should lose my files, or close and go out of business, I'll still be able of recover my files from the remaining 3 cloud providers that still work, what we have here is effectively a RAIC (redundant array of inexpensive clouds) :) 3) I could instead configure a zfec factor of 5:6 so I can maximize the space that I have striping across multiple free "few Gb" accounts like in a RAID5 pool of disks, effectively building a cheap and inexpensive big cloud disk, and still being able to recover my files in the event that one cloud provider fails." [0]

Least Authority Enterprise (LAE) Least Authority Enterprises is also working on RAIC through the use of cloud services which support an HTTP API. Sickness' implementation works instead by letting the cloud service client sync the directory in which Tahoe-LAFS stores the encrypted shares.

Sickness's approach has the advantage that it can sync with services which do not provide an API. However, this implementation depends on the correctness and availability of the syncing implementation. For example, if the Dropbox process dies, the shares are still fine on your local disk, but they are no longer being synched.

Glowing Quotes

“At Virginia Tech Linux and Unix Users Group, we have a working Tahoe-LAFS deployment of about 9-14 nodes. It's incredibly reliable. It's based at Virginia Tech, with the introducer on a university-hosted servers, plus a few nodes in the dorms. One day, VT disappeared from the net. They had a problem with one of their uplinks and all their edge routers stopped routing. The introducer and about half the nodes on the grid were down for maybe an hour. At no point was any data stored on the grid inaccessible to any of the nodes, because all the ones outside could talk to the ones outside, and the ones inside could talk to the ones inside.” — Marcus Wanner marcusw

Tahoe-LAFS on Twitter

With #I2P in 1.11! RT @zooko Plans for Tahoe-LAFS v1.9.2, v1.10, and v1.11: https://tahoe-lafs.org/pipermail/tahoe-dev/2012-May/007340.html Join us! ☺ [1]

From the tahoe-dev Mailing List

End of Support for Python 2.4

Tahoe-LAFS is at long last going to stop being backwards-compatible with Python 2.4. The plan is for the Tahoe-LAFS v1.9.2 release to be the last one that works with Python 2.4, and starting with the v1.10 release it will require Python 2.5, 2.6, or 2.7.

Authenticated Data Structures

Andrew Miller amiller wrote a dense technical post about a concept called "Authenticated Data Structures", which unifies concepts from Bitcoin, proofs-of-work, and Tahoe-LAFS append-only files or add-only sets. At press time nobody else had understood it well enough to write a reply.

New User Documentation

Michael Rogers suggested a few user-experience and documentation issues experienced by a new user trying to install Tahoe-LAFS for the first time. David-Sarah responded by creating trac tickets to track progress on Michael's issues. There was a pony involved.

Use the Source

A new user named Han Zheng asked how to get started studying Tahoe-LAFS's source code. Zooko suggested starting by reading the server implementation. Since servers aren't allowed to know anything about the plaintext in Tahoe-LAFS, they are dumber and easier to learn than the other components.

Patches Needing Review of the Week

There is two (2) ticket still needing review for 1.9.2:

There are three (3) ticket still needing review for 1.10.0:

There are three (3) tickets still needing review of 1.11.0:

The Tahoe-LAFS Weekly News is published once a week by The Tahoe-LAFS Software Foundation, President and Treasurer: Peter Secor peter . Scribes: Patrick "marlowe" McDonald marlowe , Zooko Wilcox-O'Hearn zooko , Editor: Zooko. View TWN on the web or subscribe to TWN . Send your news stories to marlowe@antagonism.org — submission deadline: Friday night.