Thread: Amazon and DRM changes
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Old 01-12-2023, 04:01 PM   #272
ownedbycats
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The difficulty of breaking KFX was described by @jhowell here:

Quote:
Amazon has implemented around 40 different DRM algorithms for KFX. They are built into the various Kindle apps and device firmware as highly obfuscated code.

Each algorithm is identified with the letter V followed by a number. So far DeDRM handles V1 though V10. Amazon is currently using V11, which DeDRM attempts to decrypt but does not do correctly.

As things stand now anyone who does figure out how to defeat the current V11 DRM has a strong incentive to keep it to themself. Keeping it quiet would mean that at least they could make use of it. Making it known to the world would just result in Amazon switching to V12, causing all of that hard work to be for nothing.

In order to defeat KFX DRM in DeDRM all of the thirty or so remaining DRM algorithms would need to be reverse engineered. If any are gotten wrong, which is likely without a way to test them properly, Amazon would immediately use that one for now and then keep adding more new ones over time.

Even if someone managed to get all of the algorithms correct, DRM removal would only work until Amazon deployed software with more new algorithms and blocked downloads to the older software.
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