System.Security.dll IL2CPP error

When building an (almost) empty project containing the file System.Security.dll as an asset for WebGL, the IL2CPP compiler errors out:

IL2CPP error for method 'System.Void Mono.Security.Cryptography.NativeDapiProtection/DATA_BLOB::Free()' in assembly 'C:\Proj\SpinningCube-5\Temp\StagingArea\Data\Managed\System.Security.dll'
Additional information: Build a development build for more information. Cannot get stack type for IntPtr​

(Note: This says to build a development build even when I am building a development build.)

Spoiler

Code (csharp):

1.  
2. Failed running C:\Program Files\Unity500f4\Editor\Data\il2cpp/il2cpp.exe --copy-level=None --enable-generic-sharing --enable-unity-event-support --enable-symbol-loading "C:\Proj\SpinningCube-5\Temp\StagingArea\Data\Managed\Assembly-CSharp.dll" "C:\Proj\SpinningCube-5\Temp\StagingArea\Data\Managed\UnityEngine.UI.dll" "C:\Proj\SpinningCube-5\Temp\StagingArea\Data\Managed\System.Security.dll" "C:\Proj\SpinningCube-5\Temp\StagingArea\Data\il2cppOutput"
3.  
4. stdout:
5. IL2CPP error for method 'System.Void Mono.Security.Cryptography.NativeDapiProtection/DATA_BLOB::Free()' in assembly 'C:\Proj\SpinningCube-5\Temp\StagingArea\Data\Managed\System.Security.dll'
6. Additional information: Build a development build for more information. Cannot get stack type for IntPtr
7. stderr:
8.  
9. Unhandled Exception:
10. System.InvalidOperationException: Cannot get stack type for IntPtr
11.  
12.   at Unity.IL2CPP.StackTypeConverter.StackTypeFor (Mono.Cecil.TypeReference type, ITypeProvider typeProvider) [0x00000] in <filename unknown>:0
13.  
14.   at Unity.IL2CPP.MethodBodyWriter.TypeForComparison (Signedness signedness, Mono.Cecil.TypeReference type) [0x00000] in <filename unknown>:0
15.  
16.   at Unity.IL2CPP.MethodBodyWriter.CastExpressionForOperandOfComparision (Signedness signedness, StackInfo left) [0x00000] in <filename unknown>:0
17.  
18.   at Unity.IL2CPP.MethodBodyWriter.ConditionalExpressionFor (System.String cppOperator, Signedness signedness) [0x00000] in <filename unknown>:0
19.  
20.   at Unity.IL2CPP.MethodBodyWriter.GenerateConditionalJump (Unity.IL2CPP.Common.CFG.InstructionBlock block, Mono.Cecil.Cil.Instruction ins, System.String cppOperator, Signedness signedness) [0x00000] in <filename unknown>:0
21.  
22.   at Unity.IL2CPP.MethodBodyWriter.ProcessInstruction (Unity.IL2CPP.Node node, Unity.IL2CPP.Common.CFG.InstructionBlock block, Mono.Cecil.Cil.Instruction ins) [0x00000] in <filename unknown>:0
23.  
24.   at Unity.IL2CPP.MethodBodyWriter.GenerateCodeRecursive (Unity.IL2CPP.Node node) [0x00000] in <filename unknown>:0
25.  
26.   at Unity.IL2CPP.MethodBodyWriter.Generate () [0x00000] in <filename unknown>:0
27.  
28.   at Unity.IL2CPP.MethodWriter.WriteMethodBody (Mono.Cecil.MethodReference method) [0x00000] in <filename unknown>:0
29.  
30.   at Unity.IL2CPP.MethodWriter.WriteMethod (Mono.Cecil.MethodReference method, MethodWriteMode mode) [0x00000] in <filename unknown>:0
31.  
32.   at Unity.IL2CPP.MethodWriter.WriteMethodAndWrappers (Mono.Cecil.MethodReference method, MethodWriteMode mode) [0x00000] in <filename unknown>:0
33.  
34.   at Unity.IL2CPP.MethodWriter.WriteMethodDefinitions (System.Func`2 filter) [0x00000] in <filename unknown>:0
35.  
36.   at Unity.IL2CPP.SourceWriter.WriteMethodDefinitionsFor (Unity.IL2CPP.CppCodeWriter writer, System.Func`2 filter, Mono.Cecil.TypeReference type, Unity.IL2CPP.Metadata.VTableBuilder vTableBuilder, Mono.Cecil.AssemblyDefinition mscorlib, Unity.IL2CPP.StringLiterals.StringLiteralCollection stringLiteralCollection) [0x00000] in <filename unknown>:0
37.  
38.   at Unity.IL2CPP.SourceWriter.WriteSource (Unity.IL2CPP.CppCodeWriter writer, Unity.IL2CPP.GenericsCollection.InflatedCollection allGenerics, Mono.Cecil.TypeReference type, System.Collections.Generic.HashSet`1 emptyTypes, Unity.IL2CPP.StringLiterals.StringLiteralCollection stringLiteralCollection) [0x00000] in <filename unknown>:0
39.  
40.   at Unity.IL2CPP.SourceWriter.WriteSourceFiles (System.String outputDirectory, System.String fileName, Unity.IL2CPP.GenericsCollection.InflatedCollection allGenerics, IEnumerable`1 typeList, System.Collections.Generic.HashSet`1 emptyTypes, Unity.IL2CPP.StringLiterals.StringLiteralCollection stringLiteralCollection) [0x00000] in <filename unknown>:0
41.  
42.   at Unity.IL2CPP.SourceWriter.Write (Mono.Cecil.AssemblyDefinition assemblyDefinition, Unity.IL2CPP.GenericsCollection.InflatedCollection allGenerics, System.String outputDir, Mono.Cecil.TypeDefinition[] typeList, Unity.IL2CPP.StringLiterals.StringLiteralCollection stringLiteralCollection) [0x00000] in <filename unknown>:0
43.  
44.   at Unity.IL2CPP.AssemblyConverter.Convert (Mono.Cecil.AssemblyDefinition assemblyDefinition, Unity.IL2CPP.StringLiterals.StringLiteralCollection stringLiteralCollection, Unity.IL2CPP.GenericsCollection.InflatedCollection allGenerics) [0x00000] in <filename unknown>:0
45.  
46.   at Unity.IL2CPP.AssemblyConverter.Apply () [0x00000] in <filename unknown>:0
47.  
48.   at Unity.IL2CPP.AssemblyConverter.ConvertAssemblies (System.String[] assemblies, System.String outputDir) [0x00000] in <filename unknown>:0
49. [ERROR] FATAL UNHANDLED EXCEPTION: System.InvalidOperationException: Cannot get stack type for IntPtr
50.  
51.   at Unity.IL2CPP.StackTypeConverter.StackTypeFor (Mono.Cecil.TypeReference type, ITypeProvider typeProvider) [0x00000] in <filename unknown>:0
52.  
53.   at Unity.IL2CPP.MethodBodyWriter.TypeForComparison (Signedness signedness, Mono.Cecil.TypeReference type) [0x00000] in <filename unknown>:0
54.  
55.   at Unity.IL2CPP.MethodBodyWriter.CastExpressionForOperandOfComparision (Signedness signedness, StackInfo left) [0x00000] in <filename unknown>:0
56.  
57.   at Unity.IL2CPP.MethodBodyWriter.ConditionalExpressionFor (System.String cppOperator, Signedness signedness) [0x00000] in <filename unknown>:0
58.  
59.   at Unity.IL2CPP.MethodBodyWriter.GenerateConditionalJump (Unity.IL2CPP.Common.CFG.InstructionBlock block, Mono.Cecil.Cil.Instruction ins, System.String cppOperator, Signedness signedness) [0x00000] in <filename unknown>:0
60.  
61.   at Unity.IL2CPP.MethodBodyWriter.ProcessInstruction (Unity.IL2CPP.Node node, Unity.IL2CPP.Common.CFG.InstructionBlock block, Mono.Cecil.Cil.Instruction ins) [0x00000] in <filename unknown>:0
62.  
63.   at Unity.IL2CPP.MethodBodyWriter.GenerateCodeRecursive (Unity.IL2CPP.Node node) [0x00000] in <filename unknown>:0
64.  
65.   at Unity.IL2CPP.MethodBodyWriter.Generate () [0x00000] in <filename unknown>:0
66.  
67.   at Unity.IL2CPP.MethodWriter.WriteMethodBody (Mono.Cecil.MethodReference method) [0x00000] in <filename unknown>:0
68.  
69.   at Unity.IL2CPP.MethodWriter.WriteMethod (Mono.Cecil.MethodReference method, MethodWriteMode mode) [0x00000] in <filename unknown>:0
70.  
71.   at Unity.IL2CPP.MethodWriter.WriteMethodAndWrappers (Mono.Cecil.MethodReference method, MethodWriteMode mode) [0x00000] in <filename unknown>:0
72.  
73.   at Unity.IL2CPP.MethodWriter.WriteMethodDefinitions (System.Func`2 filter) [0x00000] in <filename unknown>:0
74.  
75.   at Unity.IL2CPP.SourceWriter.WriteMethodDefinitionsFor (Unity.IL2CPP.CppCodeWriter writer, System.Func`2 filter, Mono.Cecil.TypeReference type, Unity.IL2CPP.Metadata.VTableBuilder vTableBuilder, Mono.Cecil.AssemblyDefinition mscorlib, Unity.IL2CPP.StringLiterals.StringLiteralCollection stringLiteralCollection) [0x00000] in <filename unknown>:0
76.  
77.   at Unity.IL2CPP.SourceWriter.WriteSource (Unity.IL2CPP.CppCodeWriter writer, Unity.IL2CPP.GenericsCollection.InflatedCollection allGenerics, Mono.Cecil.TypeReference type, System.Collections.Generic.HashSet`1 emptyTypes, Unity.IL2CPP.StringLiterals.StringLiteralCollection stringLiteralCollection) [0x00000] in <filename unknown>:0
78.  
79.   at Unity.IL2CPP.SourceWriter.WriteSourceFiles (System.String outputDirectory, System.String fileName, Unity.IL2CPP.GenericsCollection.InflatedCollection allGenerics, IEnumerable`1 typeList, System.Collections.Generic.HashSet`1 emptyTypes, Unity.IL2CPP.StringLiterals.StringLiteralCollection stringLiteralCollection) [0x00000] in <filename unknown>:0
80.  
81.   at Unity.IL2CPP.SourceWriter.Write (Mono.Cecil.AssemblyDefinition assemblyDefinition, Unity.IL2CPP.GenericsCollection.InflatedCollection allGenerics, System.String outputDir, Mono.Cecil.TypeDefinition[] typeList, Unity.IL2CPP.StringLiterals.StringLiteralCollection stringLiteralCollection) [0x00000] in <filename unknown>:0
82.  
83.   at Unity.IL2CPP.AssemblyConverter.Convert (Mono.Cecil.AssemblyDefinition assemblyDefinition, Unity.IL2CPP.StringLiterals.StringLiteralCollection stringLiteralCollection, Unity.IL2CPP.GenericsCollection.InflatedCollection allGenerics) [0x00000] in <filename unknown>:0
84.  
85.   at Unity.IL2CPP.AssemblyConverter.Apply () [0x00000] in <filename unknown>:0
86.  
87.   at Unity.IL2CPP.AssemblyConverter.ConvertAssemblies (System.String[] assemblies, System.String outputDir) [0x00000] in <filename unknown>:0
88.  
89. UnityEngine.Debug:LogError(Object)
90. UnityEditorInternal.Runner:RunManagedProgram(String, String, String, CompilerOutputParserBase) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:66)
91. UnityEditorInternal.IL2CPPBuilder:ConvertPlayerDlltoCpp(ICollection`1, String, String) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:404)
92. UnityEditorInternal.IL2CPPBuilder:Run() (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:275)
93. UnityEditorInternal.IL2CPPUtils:RunIl2Cpp(String, IIl2CppPlatformProvider, Action`1, RuntimeClassRegistry) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:218)
94. UnityEditor.HostView:OnGUI()
95.  

Spoiler

Code (csharp):

1.  
2. Exception: C:\Program Files\Unity500f4\Editor\Data\il2cpp/il2cpp.exe did not run properly!
3. UnityEditorInternal.Runner.RunManagedProgram (System.String exe, System.String args, System.String workingDirectory, UnityEditor.Scripting.Compilers.CompilerOutputParserBase parser) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:68)
4. UnityEditorInternal.IL2CPPBuilder.ConvertPlayerDlltoCpp (ICollection`1 userAssemblies, System.String outputDirectory, System.String workingDirectory) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:404)
5. UnityEditorInternal.IL2CPPBuilder.Run () (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:275)
6. UnityEditorInternal.IL2CPPUtils.RunIl2Cpp (System.String stagingAreaData, IIl2CppPlatformProvider platformProvider, System.Action`1 modifyOutputBeforeCompile, UnityEditor.RuntimeClassRegistry runtimeClassRegistry) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/Il2Cpp/IL2CPPUtils.cs:218)
7. UnityEditor.WebGL.WebGlBuildPostprocessor.PostProcess (BuildPostProcessArgs args)
8. UnityEditor.PostprocessBuildPlayer.Postprocess (BuildTarget target, System.String installPath, System.String companyName, System.String productName, Int32 width, Int32 height, System.String downloadWebplayerUrl, System.String manualDownloadWebplayerUrl, BuildOptions options, UnityEditor.RuntimeClassRegistry usedClassRegistry) (at C:/buildslave/unity/build/Editor/Mono/BuildPipeline/PostprocessBuildPlayer.cs:316)
9. UnityEditor.HostView:OnGUI()
10.  

Spoiler

Code (csharp):

1.  
2. Error building Player: Exception: C:\Program Files\Unity500f4\Editor\Data\il2cpp/il2cpp.exe did not run properly!
3.  

I'm attempting to port a webplayer game to WebGL and I do need to use some functions from System.Security. Is this a Unity bug that I should wait on Unity to fix, or something I can work around myself?