CookieAuthenticationHandler IsPersistent with UTC dates

[nickcam]

Hi Guys,

Just stumbled across a small bug I think.
Line 243 in CookieAuthenticationHandler.

if (signInContext.Properties.IsPersistent)
{
      var expiresUtc = signInContext.Properties.ExpiresUtc ?? issuedUtc.Add(Options.ExpireTimeSpan);
      signInContext.CookieOptions.Expires = expiresUtc.ToUniversalTime().DateTime;
}

The date signInContext.CookieOptions.Expires has the correct value, but it's kind is Unspecified, so when added to the cookie it gets converted to UTC again.

I've got a local copy of this class and just changed that line to
signInContext.CookieOptions.Expires = DateTime.SpecifyKind(expiresUtc.ToUniversalTime().DateTime, DateTimeKind.Utc);

and it's all good.
Thanks.

[Eilon]

Can we look into why we aren't using DateTimeOffset? That might help resolve some of this.