Date: Tue, 26 May 2015 09:25:22 -0400 From: Nick Mathewson nickm@torproject.org

I posted this on a blog comment, but others may be interested too.

As near as I can tell, the "logjam"/"weakdh" attacks should not affect current Tor software very much, for a few reasons:

• All currently supported Tor versions, when built with OpenSSL 1.0 or later, prefer 256-bit elliptic-curve Diffie Hellman for their TLS connections, not the 1024-bit Diffie Hellman over Z_p as discussed in this paper.

…

Recommendations:

…

• If you're running OpenSSL 0.9.8 or earlier, you should consider upgrading to 1.0.0 or later.

(Mac) OS X Yosemite 10.10 and earlier ship with OpenSSL 0.9.8 and 0.9.7.

For Yosemite 10.10.3 (14D136) in particular, these are:

$ ls -l /usr/lib/libssl.* -rwxr-xr-x 1 root wheel 400608 10 Sep 2014 /usr/lib/libssl.0.9.7.dylib -rwxr-xr-x 1 root wheel 616512 20 Mar 13:16 /usr/lib/libssl.0.9.8.dylib lrwxr-xr-x 1 root wheel 18 28 Jan 23:16 /usr/lib/libssl.dylib -> libssl.0.9.8.dylib

$ strings /usr/lib/libssl.0.9.8.dylib | grep "OpenSSL 0.9.8" OpenSSL 0.9.8zd 8 Jan 2015 …

$ strings /usr/lib/libssl.0.9.7.dylib | grep "OpenSSL 0.9.7" … OpenSSL 0.9.7l 28 Sep 2006 …

(As an aside, please avoid running strings on any untrusted binaries.)

While it's possible to build or install OpenSSL 1.0 or 1.1 on OS X, it's not the default.

How does this affect Tor and/or Tor Browser on OS X?

teor

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