Tarsnap 1.0.41

[Colin Percival <cperciva@tarsnap.com>]

Hi all,

Tarsnap 1.0.41 is now available.  This version brings a security improvement
and several new features compared to tarsnap 1.0.40:

* [security] Tarsnap now has mitigations to defend against information leakage
  via chunking: Chunks are padded using the PADME scheme, and small-alphabet
  cycles are prohibited in chunking to block a chosen-plaintext attack.  For
  more details on the attack, see my blog post
  https://www.daemonology.net/blog/2025-03-21-Chunking-attacks-on-Tarsnap.html
  and the paper
  "Chunking Attacks on File Backup Services using Content-Defined Chunking"
  which should be available on the Cryptology ePrint Archive shortly.

* tarsnap -c now accepts --dry-run-metadata, which simulates creating an
  archive without reading any file data.  This is significantly faster than a
  regular --dry-run, and is suitable for checking which filesystem entries
  will be archived (with -v) or checking the total archive size (with --totals
  or --progress-bytes).

* tarsnap now accepts --noatime with -c mode, which requests that the
  operating system does not update atime when reading files or directories.
  Not supported by all operating systems or filesystems.

* If the server-side state was modified and tarsnap exits with an error, it
  will now have an exit code of 2.

* tarsnap will read a config file in $XDG_CONFIG_HOME/tarsnap/tarsnap.conf;
  or ~/.config/tarsnap/tarsnap.conf if $XDG_CONFIG_HOME is not set.  The
  previous config file ~/.tarsnaprc is still supported, and will not be
  deprecated.

* tarsnap now accepts --null-input as a synonym for --null.  For compatibility
  reasons, --null is still supported, and will not be deprecated.

* tarsnap now accepts --null-output with --print-stats, --list-archives, -x,
  and -t, which produces NUL-separated output from those commands.

* A bug in tarsnap's scrypt code which caused a self-test failure when
  tarsnap is compiled on gcc and passphrased key files are used on systems
  without SSE2 (e.g. non-x86 systems) has been fixed.

As usual, there are also lots of minor build fixes, harmless bug fixes, and
code cleanups.

The new release is available from the usual location
   https://www.tarsnap.com/download.html
and the full set of changes can be see in the git repository:
   https://github.com/tarsnap/tarsnap

Users of the .deb packages we ship should find that their systems can now
fetch tarsnap 1.0.41.  Users of other packaging systems (FreeBSD / NetBSD
/ OpenBSD / Homebrew / MacPorts / Gentoo / OpenSUSE / etc.) should be able
to fetch tarsnap 1.0.41 once the maintainers of the respective ports have
updated them.

--
Colin Percival
Security Officer Emeritus, FreeBSD | The power to serve
Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid

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