Why do we need -copy-chunker-params?

1

according to the documentation
https://restic.readthedocs.io/en/latest/045_working_with_repos.html#ensuring-deduplication-for-copied-snapshots
it is needed for deduplication

But I wonder why should two init-calls (without the copy-parameter) result in different chunker parameters :thinking:

2

I think they are randomized to protect against certain techniques of guessing your (encrypted) data, or to protect against DoS attacks based on specially crafted data patterns that would trigger unlikely events at unusually high rates - which you cannot craft if you don’t know the parameters (just like salts for hash tables in some web backend scripting languages).

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3

I believe it started here:

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4

Both explanations sound logical to me.

Thanks for the hints.

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5

Will a hacker be able to crack the password when using the same chunker parameter for different repositories, especially same chunker parameter and same password for different repo?