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Merge pull request #5295 from MichaelEischer/randomize-pack-order

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Randomize blob to pack file assignment
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Michael Eischer
2025-03-25 18:13:49 +01:00
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parent 823cc3d93a 5e519a25f7
commit 13cb90b83a
10 changed files with 374 additions and 126 deletions
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@@ -755,6 +755,16 @@ An adversary with read access to your backup storage location could:
repository (please use strong passwords with sufficient entropy).
- Infer which packs probably contain trees via file access patterns.
- Infer the size of backups by using creation timestamps of repository objects.
- As shown in the paper `Chunking Attacks on File Backup Services using Content-Defined Chunking <https://eprint.iacr.org/2025/532.pdf>`_
by Boris Alexeev, Colin Percival and Yan X Zhang, an
attacker that can observe chunk sizes created for a known file can derive the secret
chunker polynomial. Knowledge of the polynomial might in some cases allow an
attacker to check whether certain large files are stored in a repository.
This has been mitigated in restic 0.18.0 by randomly assigning chunks to
pack files, which prevents an attacker from learning the chunk sizes as the
attacker can no longer determine to which file and which part of it a chunk belongs.
See `#5295 <https://github.com/restic/restic/pull/5295>`_ for more details
on the mitigation.
An adversary with network access could: