Mono xbuild error CS1548 - key file has incorrect format

So I'm trying to get a VS2010 C# project to go cross-platform. First goal is build it in Mono 2.10.5 for Windows. I have not touched any code yet - I'm starting with xbuild's recent ability to build sln files. (Incidentally I use Jenkins to trigger builds, not that it matters as I get the same result at the command-line.)

I get "error CS1548: Error during assembly signing. The specified key file `AlphaBeta.pfx' has incorrect format". There's not much google juice on this error. Does anyone know what would cause this? Thanks in advance!

Full output below:

C:\Program Files\Jenkins\jobs\AlphaBeta\...\AlphaSolution>"C:\Program Files\Mono-2.10.5\bin\xbuild" AlphaSolution.sln 
XBuild Engine Version 2.10.5.0
Mono, Version 2.10.5.0
Copyright (C) Marek Sieradzki 2005-2008, Novell 2008-2011.

Build started 9/20/2011 3:54:14 PM.

C:\Program Files\Jenkins\jobs\AlphaBeta\...\AlphaSolution\AlphaSolution.sln:  warning : Ignoring vcproj 'ZBM'.
C:\Program Files\Jenkins\jobs\AlphaBeta\...\AlphaSolution\AlphaSolution.sln:  warning : Don't know how to handle GlobalSection TestCaseManagementSettings, Ignoring.
C:\Program Files\Jenkins\jobs\AlphaBeta\...\AlphaSolution\AlphaSolution.sln:  warning : Failed to find project d393406d-3397-4907-a536-2a4b77512bc6
Project "C:\Program Files\Jenkins\jobs\AlphaBeta\...\AlphaSolution\AlphaSolution.sln" (default target(s)):
    Target ValidateSolutionConfiguration:
        Building solution configuration "Debug|Mixed Platforms".
    Target Build:
        Project "C:\Program Files\Jenkins\jobs\AlphaBeta\...\AlphaSolution\AlphaCommon\AlphaCommon.csproj" (default target(s)):
            Target PrepareForBuild:
                Configuration: Debug Platform: AnyCPU
            Target GenerateSatelliteAssemblies:
            No input files were specified for target GenerateSatelliteAssemblies, skipping.
            Target CoreCompile:
                Tool C:\PROGRA~1\MONO-2~1.5\bin\dmcs.bat execution started with arguments: /noconfig /debug:full /debug+ /keyfile:AlphaBeta.pfx /optimize- /out:obj\Debug\AlphaCommon.dll AlphaCommon.cs Properties\Ass开发者_C百科emblyInfo.cs /target:library /define:"DEBUG;TRACE" /reference:C:\PROGRA~1\MONO-2~1.5\lib\mono\xbuild-frameworks\.NETFramework\v4.0\RedistList\..\..\..\..\4.0\System.dll /reference:C:\PROGRA~1\MONO-2~1.5\lib\mono\xbuild-frameworks\.NETFramework\v4.0\RedistList\..\..\..\..\4.0\System.Xml.Linq.dll /reference:C:\PROGRA~1\MONO-2~1.5\lib\mono\xbuild-frameworks\.NETFramework\v4.0\RedistList\..\..\..\..\4.0\System.Data.DataSetExtensions.dll /reference:C:\PROGRA~1\MONO-2~1.5\lib\mono\xbuild-frameworks\.NETFramework\v4.0\RedistList\..\..\..\..\4.0\Microsoft.CSharp.dll /reference:C:\PROGRA~1\MONO-2~1.5\lib\mono\xbuild-frameworks\.NETFramework\v4.0\RedistList\..\..\..\..\4.0\System.Data.dll /reference:C:\PROGRA~1\MONO-2~1.5\lib\mono\xbuild-frameworks\.NETFramework\v4.0\RedistList\..\..\..\..\4.0\System.Xml.dll /reference:C:\PROGRA~1\MONO-2~1.5\lib\mono\xbuild-frameworks\.NETFramework\v4.0\RedistList\..\..\..\..\4.0\System.Core.dll /warn:4
: error CS1548: Error during assembly signing. The specified key file `AlphaBeta.pfx' has incorrect format
            Task "Csc" execution -- FAILED
            Done building target "CoreCompile" in project "C:\Program Files\Jenkins\jobs\AlphaBeta\...\AlphaSolution\AlphaCommon\AlphaCommon.csproj".-- FAILED

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Mono does not support using PKCS#12 (.pfx) files to store keys used for strongnaming assemblies. This is a known issue and tracked on Xamarin's bugzilla #725.

A workaround is to export your key into a .snk file and use this when building your project.

The answers here provide examples of how to generate an .snk from a .pfx.