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When I was looking at the www.bing.com/maps html source file I came across some strange "streetsidePrefetchFileUrls" URLs to .xap.png archives:

For exmaple: hxxp://c0.ecn.catalogservice.virtualearth.net/cs/dc/pf/Xaps/bcbc3954e568c46cf8c3cc00737da32c_Microsoft.Maps.Framework.xap.png

This file has a PNG Header and contains an IDAT chunk. The IDAT chunk doesn't contain pixel data but a (corrupt) PKZIP archive with Microsoft Maps DLLs inside.

Does anybody know why Microsoft uses PNG as a container for xap Archives?

I've tried to unpack that archive with unzip and 7z. They all detect the ZIP-Archive inside the PNG but abort unpacking with an error.

user1169333
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2 Answers2

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Yes I noticed this they changed to this kind of protection just before the map app api came out of Beta. I presume it is their way of providing some protection for xap code from 3rd party developers, we have tried lots of ways to decrypt these without any luck but the code for it must be in the initial silverlight code so with a lot of decompiling you could probably find it

Gingemonster
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Many of the Bing Maps App's available on http://bing.com/maps contain proprietary algorithms and code. The png encoding is there to help prevent people from decrypting the XAP files and decompiling them. That said, if there is something you are trying to figure out how to do then try asking that question instead.

rbrundritt
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