I use LUKS to encrypt all sensitive data on my computer. If I switch to using a filesystem with on-the-fly data compression such as ZFS, should I use its compression feature together with LUKS? Does compression here help the attacker as in case of TLS CRIME attack scenario?

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    It is unclear what kind of attacker you are talking about. What has the attacker access to, what can the attacker see, can the attacker interact with the file system ... ? "... as in case of TLS CRIME attack scenario" - CRIME is about the attacker defining parts of the input in order to get information about other unknown parts based on the observed compression ratio. If the attacker just has access to the encrypted disk then this attack pattern does not work. Jul 31, 2022 at 16:52

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The imaginary attacker is accessing your filesystem in offline mode - what they see is essentially pure random data. Whether it was compressed or not prior to encryption - they'll never know. The attacker cannot manipulate or deduce the data you're storing [in real time] unless they already have full real time root access to your system.

From its description:

The vulnerability exploited is a combination of chosen plaintext attack and inadvertent information leakage through data compression similar to that described in 2002 by the cryptographer John Kelsey.[3] It relies on the attacker being able to observe the size of the ciphertext sent by the browser while at the same time inducing the browser to make multiple carefully crafted web connections to the target site. The attacker then observes the change in size of the compressed request payload, which contains both the secret cookie that is sent by the browser only to the target site, and variable content created by the attacker, as the variable content is altered.

No such thing can be applied to your encrypted data.

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