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Does 7z or RAR5 offer better resistance to brute force attacks?

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  • Reduced the wordiness
    – schroeder
    Nov 12, 2023 at 18:18

1 Answer 1

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Based solely on hashcat's default benchmarks for each (shown here when run on a GTX 970 GPU - YMMV), it looks like RAR5 is marginally slower (hashes per second), and therefore more resistant to offline attack:

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* Hash-Mode 11600 (7-Zip) [Iterations: 16384]
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Speed.#1.........:     5801 H/s (87.87ms) @ Accel:128 Loops:4096 Thr:1 Vec:8


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* Hash-Mode 13000 (RAR5) [Iterations: 32799]
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Speed.#1.........:     4478 H/s (55.33ms) @ Accel:512 Loops:1024 Thr:1 Vec:8

Interestingly, the RAR3 family appears to be even slower:

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* Hash-Mode 12500 (RAR3-hp) [Iterations: 262144]
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Speed.#1.........:      760 H/s (84.05ms) @ Accel:64 Loops:16384 Thr:1 Vec:8

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* Hash-Mode 23800 (RAR3-p (Compressed)) [Iterations: 262144]
------------------------------------------------------------

Speed.#1.........:      709 H/s (89.64ms) @ Accel:64 Loops:16384 Thr:1 Vec:8

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* Hash-Mode 23700 (RAR3-p (Uncompressed)) [Iterations: 262144]
--------------------------------------------------------------

Speed.#1.........:      770 H/s (83.00ms) @ Accel:64 Loops:16384 Thr:1 Vec:8

What's not clear to me is whether the default work factors (iterations) can be customized for these file formats. If any can, they could be made more difficult to attack.

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    But isn't the number of iterations used by 7z equal to 524288 (2^19 ) ?
    – oqdn
    Nov 13, 2023 at 11:55

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