Assembly reference error (CS0234) when using System.Security.Cryptography in Xamarin Studio 6.1 on Mac OS X

Question

Running Xamarin Studio (Community) 6.1 (build 4963) on OS X El Capitan 10.11.5, I am trying to use RNGCryptoService in my solution (targets iOS and Android) for which I need to use the namespace System.Security.Cryptography. However, it seems like using System.Security.Cryptography; and then calling RNGCryptoServiceProvider random = new RNGCryptoServiceProvider(); somewhere in my code gives me the error.

Error CS0234: The type or namespace name 'Cryptography' does not exist in the namespace 'System.Security'. Are you missing an assembly reference? (CS0234)

I tried to look for the System.Security.Cryptography package in the NuGet repositories (including the pre-release versions) but I did not find anything.

What am I missing? Where can I find the assembly reference?

Answer 1

You need the System.Security.Cryptography.Algorithms package to use RNGCryptoServiceProvider . Install that with NuGet v 3.4 or later:

> PM Install-Package System.Security.Cryptography.Algorithms

You may also need to modify your project.json file to make this package a dependency of dotnet5.4 and not a global dependency to stop the compiler from complaining about duplicate class declarations.

Follow up: It looks like System.Security.dll is not supported on Xamarin.iOS or Android. As an alternative, you might have some luck with Jeffrey Stedfast's fork of the Bouncy Castle cryptography library bc-csharp for use with Xamarin.Android and Xamarin.iOS.

Another option might be to use the PCLCrypto library with this helper class and workaround for NuGet.