According to the sources, it's true that the system will authenticate games with regular online checks, but there will be special dispensation for players who don't have internet access, such as active duty soldiers in war zones.
As for used games, the sources stated, "The Xbox One will automatically authenticate a game using an encryption code built into a game's disc, when it is installed on the machine. That authentication on the console's hard drive tied to the game is then verified regularly through an internet connection. When a person sells the game or it is installed and played on another system, the game is deauthenticated on the original machine until the disc is brought back and used to re-authenticate the installation."
How in the world this will be implemented, however, is still unknown. It sounds like it'll just phone home on whatever console it is on. Does this mean Microsoft will see if the same disc is being used on 20 consoles and lock it out because of oversharing?
It may be that Microsoft will just return to what the Xbox 360 currently does: lock out modded Xboxes used for piracy and cheating when they attempt to go onto Xbox Live.