Created attachment 13723 [details]
It seems Microsoft moved the class System.ServiceModel.Security.Tokens.BinarySecretSecurityToken from System.ServiceModel assembly to System.IdentityModel assembly starting with .NET 4.5
Therefore using SymmetricKeyIssuerSecurityTokenProvider from NuGet package Microsoft.Owin.Security.Jwt under Mono/.NET 4.5 results in the following exception:
Could not load type 'System.ServiceModel.Security.Tokens.BinarySecretSecurityToken' from assembly 'System.IdentityModel, Version=18.104.22.168, Culture=neutral, PublicKeyToken=b77a5c561934e089'.)
at Microsoft.Owin.Security.Jwt.SymmetricKeyIssuerSecurityTokenProvider..ctor (System.String issuer, System.Byte key) <0x415ac7d0 + 0x0005b> in <filename unknown>:0
I opened a pull request which moves this type and a few others that were moved in .NET 4.5: https://github.com/mono/mono/pull/3763
Merged to master and mono-4.8.0-branch. Thanks!