title: SignTool internal error when trying to repackage an APPX package?
body: <p>I'm analyzing existing Windows Store applications and modifying them to make sure my company's obfuscator works with them. </p>
  
  <p>I've ran into a bit of a problem doing that though. I can grab an APPX package from the store easily enough(requires Fiddler to get the URL). I can then just use any unzip program to extract the appx to a folder. I can then take the assemblies in the APPX and modify the IL a bit. I then remake and sign the package:</p>
  
  <pre><code>makeappx pack /d "mypackage" /p "mypackage.appx"
  signtool sign /fd sha256 /f temporarykey.pfx mypackage.appx
  </code></pre>
  
  <p>I then get an error with signtool though:</p>
  
  <pre><code>SignTool Error: An unexpected internal error has occured
  Error information: "Error: SignerSign() failed." (-2147024885/0x800700b)
  </code></pre>
  
  <p>And then of course get an error when trying to install it with the standard powerscript file created by Visual Studio for installing/sideloading any APPX package.</p>
  
  <pre><code>Found package: C:\....mypackage.appx 
  Error: The package is not digitally signed or its signature is corrupted
  </code></pre>
  
  <p>I've used this exact process for packages generated from Visual Studio. Are temporary keys tied to a particular package or something? What am I missing? Is this a bug in signtool?</p>