Codecs

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dlp
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Codecs

Post by dlp » Tue Mar 06, 2012 10:53 pm

I see which 7z and RAR codecs Keka 1.0 uses in the changelog, but have a few questions.

1. For 7z, does it use the default LZMA algorithm?
2. Which ZIP codec?
3. Which AES codec?
4. Are headers encrypted when encrypted 7z or RAR output is selected?
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aone
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Re: Codecs

Post by aone » Tue Mar 06, 2012 11:13 pm

Keka uses the default 7z and unrar binaries. For compression in 7z uses the default arguments, and for Zip just the -tzip argument. Any addition.

For password protection it just uses the -p argument, so the default encryption (if any) is applied.
For headers encryption just the argument -mhe is applied, I'm not sure what are you asking about that... Note that 1.0 version has a bug and does not encrypt the headers. The 1.0.1 with this fixed is on it's way, few days to be released.

Maybe this info is not that extensive, but it is really what Keka does. Defaults :)

I've received some feedback before asking to enhance the selection of the algorithm and the encryption scheme, and sure I will try to make this a reality. Just need to find the moment.
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Re: Codecs

Post by dlp » Thu Mar 08, 2012 2:14 pm

Thanks.

I gather, then, that Keka is largely an OSX GUI interface for p7zip. How are dmgs produced and encrypted?

Is the bug in Keka 1.0's 7z header-encryption present in all the earlier versions also?
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Re: Codecs

Post by aone » Thu Mar 08, 2012 3:28 pm

It is actually a GUI. For DMG hdutil is used, and no encryption is supported right now.

The bug is only in 1.0, tha older versions are fine :mrgreen: The 1.0.1 revision should be released in a few days now.
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dlp
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Re: Codecs

Post by dlp » Thu Mar 08, 2012 9:23 pm

What's the status of Tickets 13, 18, 29, & 45? It appears that 13 & 45 are internal to p7zip and therefore beyond your control.

Are we supposed to be able to add comments to existing tickets? I'm unable to, but perhaps that's a browser problem.
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Re: Codecs

Post by aone » Thu Mar 08, 2012 11:03 pm

Ticket 13 needs a new p7zip version. The ticket in p7zip (link available in ticket 13) remains active, so I'm not sure if this is fixed.
About the ticket 18, this is a thing I've in mind. As I told you only need the time to implement it.
About the ticket 29, with binaries I can't do anything right now. One of the most important changes in the upcoming versions of Keka is using libraries instead of binaries. This will take time, but it's a priority for the project.
About the ticket 45, thanks for pointing me to it since I've not seen the answer with the password. I'll take a look.

I'm usually posting updates in the tickets, so they are updated. The status you see in the trac is the status I've resumed here ;)

You need to be registered to post comments. I've started with guest support in the trac, cause I'm the first who doesn't like to register in every web, but the spam started on the first day. Is the only requirement. Tell me if you have an account and can't post comments or create tickets! I'm always browsing with WebKit but sometimes in Firefox or IE and never found that problem.
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Re: Codecs

Post by dlp » Fri Mar 09, 2012 1:13 am

Aha. I didn't realize another registration is needed for the tickets. Thanks.

BTW, I like Keka's GUI. It's simple and intuitive, and it has a small desktop footprint. This should appeal to the majority of users, who need only to expand and occasionally compress, and don't care about archiving. If you add the ability to poke around inside archives, add and delete things, etc. as someone else requested, I suggest the larger interface that will require appear only if the user does something to trigger it.
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Re: Codecs

Post by aone » Tue Mar 13, 2012 3:48 pm

First I must implement it :) I'll try to use source code instead of binaries, then this will be a non brainer
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Re: Codecs

Post by aone » Tue Mar 13, 2012 4:08 pm

But good point anyway, I think like you, this don't have to mean transform Keka into a Winrar or similar. A better way must be done :)
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Re: Codecs

Post by dlp » Tue Mar 13, 2012 5:43 pm

this don't have to mean transform Keka into a Winrar or similar. A better way must be done :)
Yes, we agree completely.

All of the OSX archive utilities I know of that support traditional archiving functions allow the user to set default compression parameters that apply when files are dropped onto the app's icon. This avoids the need to draw a huge interface, showing the contents, etc. If the user wants that sort of interface, it can be opened another way. You might want to study Archiver and Entropy, if you haven't already -- they also have especially well designed user interfaces, in my opinion.

A nice touch for that larger interface would be automatic computation and display of various hashes (MD5, SHA-2, etc.) for the archive. sArchiver will compute MD5, but not other hashes, and the user has to click a button to get it.

Getting back to codecs, though: Do you use the solid-archive option for RAR and 7z? That option probably yields the best compression, unless you want to try using different algorithms according to the filetype, like Stuffit does, for example.

Also, for 7z, the LZMA2 option probably gives better compression in most cases than LZMA.
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