Because the archive servers will make a public Bazaar branch available, cloning is as simple as branching. Bazaar handles all necessary locking, digital signature verification, and data transfer. Updating a clone is efficient with Bazaar's "pull" command; only new data will transfer.
Ideally, an archive server would store configuration in its Bazaar branch(es), allowing cloning to happen with only the built-in Bazaar branch and pull operations.