EzyDepot:
An Easy Public Writing Database

EzyDepot is a permissionless blockchain to have security, scalability and decentralization properties together plus greenness. Its block extending algorithm involves a noisy drawing-lots Proof-of-Luck (PoL) game to select a lucky block out of many contending blocks. Let the lucky block record, not only a payload chunk for inputting users’ writing entries to the blockchain database (DB), but also the public key identities of some “unlucky” blocks’ finders, just as recording “uncle block miners” by the GHOST (Greedy Heaviest Observed SubTree) algorithm in Ethereum’s Proofs-of-Work (PoW) version. As in GHOST, these “unlucky” blocks finders in EzyDepot are also dearly called “uncles”. A novel use of the uncles is for them to have the exclusive entitlement to announce correctness verdicts on the user entries to write the DB. By controlling the PoL traffic not to reach a spam level as GHOST doing for its uncles, the uncles’ verdicts spread the peer-to-peer (P2P) gossip network in good order. With uncles in endless supply, the correct user entries are approved by the uncles’ dissemination to saturate the distributed public-writing DB with the efficiency of an epidemic algorithm, and the incorrect ones are discarded in early gossip hops. Thus, the uncles can guarantee the correctness for the public-writing DB in the same function of probability amplification guaranteeing for randomized probabilistic (RP) algorithms. In fact, the uncles’ probability amplification function can prevent concentration of attacking power for a so-called “51% Attack”. As contribution to knowledge, the work of EzyDepot establishes:

$$ \mbox{Blockchains} \subset \mbox{RP(ZPP)} $$

In addition to improving permissionless blockchain for the open ledger usecase, EzyDepot also lines up uncle nodes as an unbound supply of IT resource to organize an open cloud hosting general-purpose P2P applications.

Key Words and Phrases:  Secure, Scalable, Decentralized and Green Permissionless Blockchain.  Proofs-of-Luck (PoL).  Novel Use of GHOST Uncles.  Probability Amplification for Blockchain as a Randomized Probabilistic (RP) Algorithm.  Blockchain as a Fair and Efficient Epidemic Algorithm.  Non-Append-Only Structure for Blockchain Database.  No 51% Attack.  P2P Cloud.