[UWP] Cryptography.ProtectedData version 7.0 => System.PlatformNotSupportedException

[jp-weber]

Description

If I install the current System.Security.Cryptography.ProtectedData version (7.0), I get following error message:

System.PlatformNotSupportedException: 'Windows Data Protection API (DPAPI) is not supported on this platform.'

With the previous version all runs well.

Reproduction Steps

1. App with UWP target
2. Install System.Security.Cryptography.ProtectedData
3. Access the api => crash

Expected behavior

No exception

Actual behavior

See description

Regression?

No response

Known Workarounds

Install System.Security.Cryptography.ProtectedData version 6.0

Configuration

• Windows 10 19045.2311
• Visual Studio 2022 17.4.0
• UWP MinTarget 1809, Target 2004

Other information

No response

Tagging subscribers to this area: @dotnet/area-system-security, @vcsjones
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Issue Details

---

Description

If I install the current System.Security.Cryptography.ProtectedData version (7.0), I get following error message:

System.PlatformNotSupportedException: 'Windows Data Protection API (DPAPI) is not supported on this platform.'

With the previous version all runs well.

Reproduction Steps

1. App with UWP target
2. Install System.Security.Cryptography.ProtectedData
3. Access the api => crash

Expected behavior

No exception

Actual behavior

See description

Regression?

No response

Known Workarounds

Install System.Security.Cryptography.ProtectedData version 6.0

Configuration

• Windows 10 19045.2311
• Visual Studio 2022 17.4.0
• UWP MinTarget 1809, Target 2004

Other information

No response

Author:	jp-weber
Assignees:	-
Labels:	area-System.Security
Milestone:	-

[adamsitnik]

@ViktorHofer I am trying to understand why this has stopped working. The System.Security.Cryptography.ProtectedData.csproj uses following settings:

<TargetFrameworks>$(NetCoreAppCurrent)-windows;$(NetCoreAppCurrent);$(NetCoreAppMinimum)-windows;$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>

<GeneratePlatformNotSupportedAssemblyMessage Condition="'$(IsPartialFacadeAssembly)' != 'true' and '$(TargetPlatformIdentifier)' != 'windows'">SR.PlatformNotSupported_CryptographyProtectedData</GeneratePlatformNotSupportedAssemblyMessage>

Is UWP consuming the netstandard2.0 package from all the above? Is it possible that after your changes from #64500 the TargetPlatformIdentifier is not set to windows for UWP?

[ViktorHofer]

@ViktorHofer I am trying to understand why this has stopped working. The System.Security.Cryptography.ProtectedData.csproj uses following settings:

UWP doesn't use .NETCoreApp target framework monikers like netcoreapp3.1, net6.0, net7.0. Instead, it uses the uap10.0.xxxxx target framework moniker. Therefore, the UWP client application picks the netstandard2.0 asset from the package which is a PlatformNotSupportedException throwing assembly as we intentionally don't provide a runtime agnostic implementation for System.Security.Cryptography.ProtectedData anymore.

@jp-weber is it possible for you to stay on the 6.0.x version of ProtectedData or retarget your app model to use .NET 6+ with WinUI?

[jp-weber]

@ViktorHofer
Oh that is sad, currently I have a class library with targets NetStandard2.0 for UWP, and NET7.0 for all other. I would like to be able to use the current version under UWP.

Due to the current status of WinUI3/WindowsAppSDK, an update to WinUI3 is not an option now and will only be possible in many years.

[vcsjones]

We could change this to be a runtime check on .NET Standard and remove the GeneratePlatformNotSupportedAssemblyMessage. @ViktorHofer @bartonjs does that seem like a viable path forward?

[ViktorHofer]

We discussed something similar offline. Could we do that for all tfms, not just netstandard2.0? Asking as PNSE assemblies increase the package size.

[ViktorHofer]

@jp-weber this just got fixed by @vcsjones in #80158 and will be available as a preview nuget package when 8.0 Preview 1 releases.