**WARNING**: a critical bug affects version 1.0.22 through 1.0.27
http://www.daemonology.net/blog/2011-01-18-tarsnap-critical-security-bug.html

Changes since 1.0.23:
* Build process reorganization: Code shared between the tarsnap client
  code and the tarsnap-keygen and tarsnap-keymgmt utilities is built
  into a library and then accessed from there instead of being compiled
  multiple times.
* The autoconf version of Tarsnap (above) should now be used on all
  supported platforms, including FreeBSD; there is no longer a "native"
  FreeBSD source tarball.
* Source code reorganization: Several source files added in version
  1.0.22 have been moved in order to make it easier to keep it in sync
  with scrypt source code.
* Updated to use libarchive 2.7.0: This brings improved UTF8 / Unicode
  and extended attribute support, along with minor bug fixes.