Signed maps

Signed maps are layergroup configurations that are granted permission to access the database on the behalf of CartoDB users other than the one logged in at usage time.

Any CartoDB users may sign any layergroup configuration and optionally specify an authorization method that a web user would be required to pass in order to use the grant.

When fetching tiles or grids from a map, a web user may reference a "signing" CartoDB user to request that the database access occurs in her behalf, eventualy providing the required authorization information.