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#136 | ||||
Connoisseur
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Join Date: May 2015
Device: iPad 1/2/Air, K3/PW2/Fire1, Kobo Touch, Samsung Tab, Nook Color/Touch
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The strings in the KFX file that state the encryption algorithm and compression method are some pretty good hints, but the key could be anywhere. Given the mention of "vouchers", and the voucher file in the KFX metadata, that would be a good place to start. But the key could also be hard-coded into the reader software (as a default for "non-DRMed" books), or the software could use a key-derivation algorithm, using something in the file or metadata as input. The possibilities are limited only by how creative Amazon wanted to be. So while someone could be motivated enough to crack KFX, I doubt they'd do it without prying apart the reader software itself to see what it was doing. Quote:
I can see how, if that's true, then from the Calibre viewpoint KFX is not something you'd invest time in. Quote:
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#137 |
Resident Curmudgeon
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Location: Roslindale, Massachusetts
Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3
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To phase out Mobi & KF8, Amazon would have to abandon every 1st gen, 2nd gen, K3, KK, Kindle Touch, Kindle Basic 1, Kindle Basic 2, DX, DXG, older versions of Kindle programs, and any other hardware I left out.
Do you really think Amazon would abandon all of these users for KFX? I would say Amazon would not do that. |
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#138 | |
Grand Sorcerer
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Location: Pennsylvania
Device: Huawei MediaPad M5, LG V30, Boyue T80S, Nexus 7 LTE, K3 3G, Fire HD8
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#139 |
creator of calibre
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Location: Mumbai, India
Device: Various
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@mattmc: My deduction that KFX is device specific is simply from data in this thread. Namely:
1) Images are grayscaled for e-ink screens 2) Images are re-compressed using a higher compression ratio (JPEG XR) 3) Since amazon has only enabled "advanced" typography for this format, it stands to reason that there is some pre-processing done to make those features easier to implement. For instance, adding soft-hyphens to the text, to avoid the layout engine on the Kindle from having to do that at runtime. It is unlikely in my opinion that the HTML/CSS is simply copied unchanged from azw3 to kfx. Of course this cannot be known for certain unless the obfuscation is broken. |
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#140 | ||||||
Grand Sorcerer
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Join Date: Nov 2011
Location: Charlottesville, VA
Device: Kindles
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It appears that protection is being applied to all KFX books. The first three bytes in the main file of every KFX book I have checked are 'D', 'R', 'M'. I wouldn't want to try to defend the position that it isn't actual DRM in court. I have heard enough about the DMCA to be cautious. Some relevant quotes from Wikipedia (highlights mine): Quote:
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There may be a reason why KFX is currently only available on the most locked down platforms. The DMCA also applies to Amazon's copyrighted software. Delving into how KFX works by examining software could be considered a criminal activity since Amazon has taken steps to protect access to that software. See this article on the same issue related to Volkswagen's misdoings. Quote:
Others may do as they wish. I am going to be cautious. |
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#141 | ||
Grand Sorcerer
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Location: Charlottesville, VA
Device: Kindles
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Beside that, it is still early days for KFX. It is only supported by a handful of devices. It would still be easy for Amazon to further enhance their DRM. The apparent lack of locking to a particular device/account is a good thing for users. It would be bad to give Amazon incentive to change that. Over time it will become harder for them to change the DRM scheme for KFX. Best for us users if hackers keep quiet until 'tools' are truly needed. Quote:
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#142 | |
Grand Sorcerer
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The main DRMION file, which apparently holds the non-image data, differs in size and (unreadable encrypted) content. Though as far as I can tell the text renders the same on both devices. |
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#143 |
Grand Sorcerer
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Device: Kindles
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One small piece of information I have found is that the metadata.kfx file is optional. I have downloaded several book samples in KFX format and none of them have had an associated metadata.kfx file.
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#144 | |||||
Connoisseur
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Device: iPad 1/2/Air, K3/PW2/Fire1, Kobo Touch, Samsung Tab, Nook Color/Touch
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@kovid, On the soft hyphens, maybe you can clear something up for me. What benefit would there be to adding those to the file itself? What if the user sets a font size that doesn't give a word a reason to break on a particular line? Then you just have a hyphen in the middle of a word...unless the rendering engine is hiding them when they're not necessary, or something, and then you haven't gained anything. I suppose they could be inserting invisible markers in the middle of words that the rendering engine uses as clues to do soft-hyphenation. Quote:
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![]() I'm curious what your take is on the proofing aspect, since you probably have the most skin in the game out of anybody, and perhaps the strongest working relationship with Amazon. Have you spoken with anyone there about giving creators the ability to proof stuff in KFX? Is it too early to get into that yet? Or are you confident enough in the simplicity of your files that you're not overly concerned about the KFX conversion playing havoc with them? Would appreciate your 2 cents ![]() (Also, how does KFX raise the bar of required skill to create an eBook? I'm not clear on that point.) |
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#145 | |
Grand Sorcerer
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Device: EB 1150, EZ Reader, Literati, iPad 2 & Air 2, iPhone 7
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I am also beginning to believe that AZK is an intermediate design and will be dropped in favor of KFX, particularly due to the similarities and the fact that KFX is now on Apple based products. Dale |
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#146 |
creator of calibre
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@mattmc: Inserting soft hyphens before hand means the text rendering engine does not have to figure out the positions at which it is suitable to insert hyphens in a word by itself. This makes its performance somewhat better and means the rendering engine does not have to ship with large collections of language specific hyphenation rules.
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#147 | |||
Grand Sorcerer
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I highly doubt they would put any resources into firmware upgrades for outdated models. If anything, when the time comes, they could offer an attractive trade-in or sale on the lowest-end current model to promote upgrades. Quote:
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Last edited by jhowell; 10-01-2015 at 02:16 PM. |
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#148 | ||||||
Bookmaker & Cat Slave
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We've tried to be careful around using fonts, but as I've mentioned before, we do a LOT of white-label work, in which we essentially have no say, other than "how high?" In terms of your question about "Also, how does KFX raise the bar of required skill to create an eBook?" my answer is a) I don't know, and b) I suspect it might. To wit: here's what we all don't know: we all don't yet know if every bloody book out there, that has escaped into the KDP, over the last 7-ish years, will be reprocessed. Now, having been the victim, more than once, of changes at the KDP, in which X worked on Monday, and didn't on Friday, that part scares my skivvies. We don't know if "advanced typography" means that EVERY SINGLE UPLOADED WORD FILE out there with empty paras in it is going to be reprocessed, with results meaning NO blank space (top margin, bottom margin, whatever). We all know that we've seen kluges over the years to do things (thank God, I think I only did this ONCE, in 2009-10), like center a title page, vertically. Using the dreaded empty paras, OR, for that matter, who amongst us--now, fess up, boys--hasn't used an NBSP in a table, to make the content "look right?" So: if all the books that e'er were, and e'er shall be, are going to be REPROCESSED, I foresee...bad. We already get a ridiculous number of requests to "fix my book" (all for $5, or $25, or whatever), from users of this or that program, or software, or browser-based SAS app. (No, Kovid, I'm not talking about Calibre, particularly.) Can't know yet. We're going to have to wait, to see what happens. I'm holding my breath. I already get people who come to me (no, I'm not making this up) 3, 4 YEARS after we've made an ePUB for them, upset because NOW, some 4 years later, the damned ePUB won't intake at iBooks or wherever, because the bloody thing won't validate, naturally. And that's the wee percentage that venture forth from Amazon, into the scary waters of "other retailers." If all the books are RE-processed, and if what you've all seen, thus far, holds....And not even just that. Amazon's made a boatload of OTHER changes over the years, but they didn't mass-re-process the books. They made the changes at the intake, or the PW (Publishing Workflow), e.g., the SRL change. When that happened, books that had been made earlier, say, 2010, would now not work correctly, for SRL, etc., because they'd been made under an earlier standard/requirement/PW. Who knows what on earth will happen if, essentially, all the MOBIs are effectively put through the PW again? Zoiks. (Sorry, Kovid: but he asked. I know you wanted to keep this on the tech, not typographic side, but it would be rude of me not to reply.) Hitch |
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#149 |
Grand Sorcerer
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(I'm fascinated, Hitch!)
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#150 |
Bookmaker & Cat Slave
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