finish poking at the changelog

Changes in version 0.2.4.8-alpha - 2013-01-14

  Tor 0.2.4.8-alpha introduces directory guards to reduce user enumeration

  risks, adds a new stronger and faster circuit handshake, and offers

  stronger and faster link encryption when both sides support it.

  o Major features:

    - Preliminary support for directory guards (proposal 207): when

      possible, clients now use their entry guards for non-anonymous

      directory requests. This can help prevent client enumeration. Note

      that this behavior only works when we have a usable consensus

      directory: and when options about what to download are more or

      less standard. Resolves ticket 6526.

    - Tor servers and clients now support a better CREATE/EXTEND cell

      directory, and when options about what to download are more or less

      standard. In the future we should re-bootstrap from our guards,

      rather than re-bootstrapping from the preconfigured list of

      directory sources that ships with Tor. Resolves ticket 6526.

    - Tor relays and clients now support a better CREATE/EXTEND cell

      format, allowing the sender to specify multiple address, identity,

      and handshake types. Implements Robert Ransom's proposal 200;

      closes ticket 7199.

    - Tor now supports a new circuit extension handshake designed by Ian

      Goldberg, Douglas Stebila, and Berkant Ustaoglu. Our original

      circuit extension handshake, later called "TAP", was a bit slow

      (especially on the server side), had a fragile security proof, and

      (especially on the relay side), had a fragile security proof, and

      used weaker keys than we'd now prefer. The new circuit handshake

      uses Dan Bernstein's "curve25519" elliptic-curve Diffie-Hellman

      function, making it significantly more secure than the older

      Implements proposal 216; closes ticket 7202.

  o Major features (better link encryption):

    - Servers can now enable the ECDHE TLS ciphersuites when available

      and appropriate. These ciphersuites let us negotiate forward-

      secure TLS secret keys more safely and more efficiently than with

      our previous use of Diffie-Hellman modulo a 1024-bit prime.

      By default, public servers prefer the (faster) P224 group, and

      bridges prefer the (more common) P256 group; you can override this

      with the TLSECGroup option.

    - Relays can now enable the ECDHE TLS ciphersuites when available

      and appropriate. These ciphersuites let us negotiate forward-secure

      TLS secret keys more safely and more efficiently than with our

      previous use of Diffie-Hellman modulo a 1024-bit prime. By default,

      public relays prefer the (faster) P224 group, and bridges prefer

      the (more common) P256 group; you can override this with the

      TLSECGroup option.

      Enabling these ciphers was a little tricky, since for a long time,

      clients had been claiming to support them without actually doing

      so, in order to foil fingerprinting. But with the client-side

      implementation of proposal 198 in 0.2.3.17-beta, clients can now

      match the ciphers from recent Firefox versions *and* list the

      ciphers they actually mean, so servers can believe such clients

      ciphers they actually mean, so relays can believe such clients

      when they advertise ECDHE support in their TLS ClientHello messages.

      This feature requires clients running 0.2.3.17-beta or later,

      and requires both sides to be running OpenSSL 1.0.0 or later

      with ECC support. OpenSSL 1.0.1, with the compile-time option

      "enable-ec_nistp_64_gcc_128", is highly recommended. Implements

      the server side of proposal 198; closes ticket 7200.

      "enable-ec_nistp_64_gcc_128", is highly recommended.

      Implements the relay side of proposal 198; closes ticket 7200.

  o Major bugfixes:

    - Avoid crashing when, as a node without IPv6-exit support, a

    - Avoid crashing when, as a relay without IPv6-exit support, a

      client insists on getting an IPv6 address or nothing. Fixes bug

      7814; bugfix on 0.2.4.7-alpha.

      upon the number of hop-RTTs that a particular circuit type

      undergoes. Additionally, launch intro circuits in parallel

      if they timeout, and take the first one to reply as valid.

    - Work correctly on unix systems where EAGAIN and EWOULDBLOCK are

      separate error codes--or at least, don't break for that reason.

    - Work correctly on Unix systems where EAGAIN and EWOULDBLOCK are

      separate error codes; or at least, don't break for that reason.

      Fixes bug 7935. Reported by "oftc_must_be_destroyed".

    - Update to the January 2 2013 Maxmind GeoLite Country database.

  o Minor features (testing):

    - Add benchmarks for DH (1024-bit multiplicative group) and ECDH

      (P-256) diffie-hellman handshakes to src/or/bench.

      (P-256) Diffie-Hellman handshakes to src/or/bench.

    - Add benchmark functions to test onion handshake performance.

  o Minor features (path bias detection):

      makes us more resilient to ambient circuit failure without any

      detection capability loss.

  o Minor bugfixes:

  o Minor bugfixes (log messages):

    - Rate-limit the "No circuits are opened. Relaxed timeout for a

      circuit with channel state open..." message to once per hour to

      keep it from filling the notice logs. Mitigates bug 7799 but does

  o Minor features:

    - Update to the January 2 2013 Maxmind GeoLite Country database.