After using JsonWebTokenHandler in. net8, when SaveSigninToken=true is set, BootstrapContext is always null

[adomass]

After using JsonWebTokenHandler in. net8, when SaveSigninToken=true is set, BootstrapContext is always null (ClaimsIdentity) user Identity) BootstrapContext is always null

Originally posted by @igaobingbing in https://github.com/dotnet/aspnetcore/issues/52075#issuecomment-1822292269

[adomass]

Its a bit strange that default behavior was changed and SaveSigninToken is not marked as obsolete, but also not respected in the code anymore. This is breaking change, because implementations that were relying on BoostrapContext in ClaimsIdentity being not null started failing. And setting options.UseSecurityTokenValidators = true;is not the best solution as well.

Are there any technical limitations that prevents from storing raw token in ClaimsIdentity?

Sure I can do workaround like this myself, but I don't think it has to be by design like this:

options.Events = new JwtBearerEvents
                {
                    OnTokenValidated = context =>
                    {
                        if (context.Options.TokenValidationParameters.SaveSigninToken && context is { SecurityToken: JsonWebToken jsonWebToken, Principal.Identity: ClaimsIdentity claimsIdentity })
                            claimsIdentity.BootstrapContext = jsonWebToken.EncodedToken;
                        return Task.CompletedTask;
                    }
                };

[sliekens]

I also just encountered this as I was trying to access the JWT in a custom IClaimsTransformation since I need the JWT to perform an on-behalf-of authentication flow with the claims provider.