  At the heart of state machine replication, the celebrated technique enabling
decentralized and secure universal computation, lies Atomic Broadcast, a
fundamental communication primitive that orders, authenticates, and
deduplicates messages. This paper presents Chop Chop, a Byzantine Atomic
Broadcast system that amortizes the cost of ordering, authenticating and
deduplicating messages, achieving "line rate" (i.e., closely matching the
complexity of a protocol that does not ensure any ordering, authentication or
Byzantine resilience) even when processing messages as small as 8 bytes. Chop
Chop attains this performance by means of a new form of batching we call
distillation. A distilled batch is a set of messages that are fast to
authenticate and deduplicate, as well as order. Batches are distilled using a
novel interactive mechanism involving brokers, an untrusted layer of
facilitating processes between clients and servers. In a geo-distributed
deployment of 64 medium-sized servers, with clients situated cross-cloud, Chop
Chop processes 43,600,000 messages per second with an average latency of 3.6
seconds. Under the same conditions, state-of-the-art alternatives offer two
orders of magnitude less throughput for the same latency. We showcase three
simple Chop Chop applications: a Payment system, an Auction house and a "Pixel
war" game, respectively achieving 32, 2.3 and 35 million operations per second.
