Ubisoft made a slight... let's call it a miscalculation, in releasing the PC version of Eric Chahi's From Dust with a built-in Digital Rights Management protocol that requires the game to have an always-on Internet connection in order to be played. For a game that has no multiplayer or any other online component, most rightly see the protective measure as a little bit excessive.
The publisher has heard your complaints, and confirmed in a forum post that an upcoming patch will get rid of the game's online authentication requirement. The patch will arrive in two weeks or so, time that Ubi's coders need to ensure that the patch preserves any saved games by transferring them from their remote storage location to players' computers.
Source: Ubisoft forums