The guarded box signing keys live in — identity's vault for shipping apps, held close and backed up closer.
Old English caeg (key) joined to store, from Old French estorer (to build, establish), from Latin instaurare (to renew, restore); a modern compound for the guarded place where signing keys are kept.
A vault for the identity that lets an app be trusted as itself, held close and backed up closer because losing it means losing that trust.