  We introduce Blockene, a blockchain that reduces resource usage at member
nodes by orders of magnitude, requiring only a smartphone to participate in
block validation and consensus. Despite being lightweight, Blockene provides a
high throughput of transactions and scales to a large number of participants.
Blockene consumes negligible battery and data in smartphones, enabling millions
of users to participate in the blockchain without incentives, to secure
transactions with their collective honesty. Blockene achieves these properties
with a novel split-trust design based on delegating storage and gossip to
untrusted nodes.
  We show, with a prototype implementation, that Blockene provides throughput
of 1045 transactions/sec, and runs with very low resource usage on smartphones,
pointing to a new paradigm for building secure, decentralized applications.
