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Implementation Details for UTXO Set Snapshots#

The UTXO set authentication uses an AVL+ tree, outlined in this research paper and available in the Scrypto framework on GitHub. Snapshots are taken every 51,200 blocks (~72 days), specifically after a block where h % 51200 == 51199.

This research paper indicates that this method can be as secure as processing all blocks under certain statistical assumptions.

Implementation Details#

Chunk Format#

To be provided

Manifest Format#

To be provided

Networking Layer#

To be provided

Bootstrapping#

To be provided

Node Configuration#

Bootstrapping with a UTXO set snapshot is enabled by setting ergo.node.utxoBootstrap = true in the configuration.

Sync Info V3#

To be provided

Technical Workflow (WIP)#

A pruned client downloads all headers, validates proofs-of-work, and links structures, followed by downloading a UTXO snapshot from peers and the full blocks succeeding it. The process is as follows:

  1. ErgoSyncInfo: Message to connected peers.
  2. Receive INV message with better block ids.
  3. Request headers for received ids.
  4. On Header Reception: 
    if(History.apply(header).isSuccess) {
    if(!(localScore == networkScore)) GOTO 1
    else GOTO 5
} else {
    blacklist peer
}
  5. Request UTXOManifest for at least BlocksToKeep back.
  6. On UTXOSnapshotManifest Reception: 
    UTXOSnapshotManifest.chunks.foreach { chunk =>
    request chunk from sender() //Or from random full node
}
  7. On UTXOSnapshotChunk Reception: 
    State.applyChunk(UTXOSnapshotChunk) match {
     case Success(Some(newMinimalState)) => GOTO 8
     case Success(None) => stay at 7
     //Request missed chunks periodically
     case Failure(e) => ???
     //Invalid hash or state
}
  8. Request BlockTransactions starting from available State. 
    History.headersStartingFromId(State.headerId).foreach { header =>
    send message(GetBlockTransactionsForHeader(header)) to Random full node
}
  9. On BlockTransactions Reception: same as Fullnode.7.
  10. Operate as Fullnode.

This revised workflow streamlines the operation of a pruned full node, emphasizing efficiency and security, positioning Ergo and similar blockchains for broader adoption within the constraints of typical hardware. For a deeper dive into nipopows, you can explore this paper.