Generate PowerBI Embedded Token on .NET CORE 1.0

I'm hitting a problem where my Linux CentOS 7 does not compile .NET CORE 1.0 code fromhttps://github.com/Azure-Samples/power-bi-embedded-iframe/blob/master/PBIEmbedded/PowerBIToken.cs#L144

This class won't compile on .NET Core 1.0 because there's no InMemorySymmetricSecurityKeyobject in .NET Core version of System.IdentityModel.Tokens

I think the real problem is the class SigningCredentials - it only takes 2 params where as in common .NET it takes 3 params at least: key, signature, digest. Currently I'm getting 'Forbidden' error from REST API calls, I suspect the part for SigningCredentials is wrong.

My objective is to generate a token to communicate with PowerBIEmbedded REST APIs.

Is there any ways to generate a PowerBI authorize token?