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Trusted Applications

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We all know Safari’s rather annoying habit of ‘warning’ you about files you download. Applications could be dangerous, as could Dashboard widgets. Certain archive files could contain dangerous material. And some obviously innocent files – certificate downloads from Thawte, say – just happen to throw a warning as well because their name ends in ‘.exe’ which makes them look dangerous as well.

Screenshot of Safari's 'dangerous' download warning sheet

This behaviour of Safari has been called annoying many and some of the Safari hacks even started to include options to deactivate it. Seeing that the ‘warning’ sheet comes up for so many downloads and that you’ve probably moved on to just dismissing it without further ado whenever it happens to be there by now, it can even be said that this sheet is a particularly Windows-esque aspect of Mac OS X: Causing users to ignore things because he’s confronted with them so many times when there’s no need to be informed of warned.

Somehow I never bothered to install any of the Safari hacks to turn off that sheet and so I was very happy to run into this page which describes how you can change the ‘danger’ Safari assigns to files. All it takes is a simple property list file called com.apple.DownloadAssessment.plist in your Preferences folder:

Example Download Assessment.plist with the LSRiskCategoryNeutral, LSRiskCategorySafe, LSRiskCategoryContentTypes and LSRiskCategoryExtensions keys

The idea is quite simple: You can set the danger level that is to be applied to files of a certain UTIs or file name extension. In particular you can set files to be ‘neutral’, which keeps Safari from annoying you with that sheet. And you can go a step further by marking file types as ‘safe’, so Safari will process them after the download finished. So if you have ever been annoyed by zip files and disk images being automatically processed by Safari but by tar files or Stuffit archives just sitting around in your downloads folder untouched, this will be for you. Be sure to read the explanations in the original article for full details.

It’s not a perfect solution for those tar files, though. Rather it looks like the MacOS comes with the BOMArchiveHelper application which can decompress a fair amount of archive formats but Safari ends up using its own code to decompress those zip archives (with the nice side-effect of trashing the zip file once it’s been decompressed). With the change to the DownloadAssessment file you’ll only make those other archive files be processed externally and their archive files will stay around in your downloads folder. Not exactly an elegant design by Apple, I’d say.

While this feature doesn’t seem to be documented at all by Apple – at least Google won’t find any of the strings in there on apple.com – it suggests that Safari’s annoying sheet isn’t just an annoyance of Safari but ties into a greater security concept (the quality of which remains to be seen).

January 9, 2006, 1:07

Tagged as Mac OS X.


Comment by Dylan: User icon

I can’t find that file…

February 15, 2006, 5:53

Comment by ssp: User icon

But you can download it.

February 15, 2006, 10:25

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Received data seems to be invalid. The wanted file does probably not exist or the guys at last.fm changed something.