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Block Lattice

The Block Lattice is the fundamental data structure of the Kakitu protocol. It replaces the traditional single-chain blockchain with a collection of independent account chains.

Structure

Each account in Kakitu has its own account chain — an ordered sequence of blocks. Each block references the hash of the previous block in the same chain, forming a linked list.

Account A:                    Account B:

┌─────────┐                   ┌─────────┐
│  open   │                   │  open   │
│ balance │                   │ balance │
│   10    │                   │    5    │
└────┬────┘                   └────┬────┘
     │                             │
┌────▼────┐                   ┌────▼────┐
│  send   │──────────────────►│ receive │
│   →B    │    "5 KSHS"       │  ←A     │
│ balance │                   │ balance │
│    5    │                   │   10    │
└─────────┘                   └─────────┘

The transfer of value between accounts requires two blocks:

  1. A send block on Account A's chain, reducing A's balance and specifying B as the destination
  2. A receive block on Account B's chain, increasing B's balance and referencing the send block hash

Why Two Blocks?

The two-block model enables asynchronous transfers:

  • The send block is broadcast immediately when the sender is ready
  • The receive block is created when the receiver comes online and processes receivables
  • Funds remain in a receivable state indefinitely between the send and receive

This is different from traditional blockchains where both parties must be represented in a single shared transaction.

Benefits: - Receiver does not need to be online for the sender to send - Each account chain can be updated independently and in parallel - No global ordering of transactions is required

Block Relationships

Each state block on a Kakitu account chain contains:

  • previous — hash of the prior block (creates the chain link)
  • balance — the account balance after this block executes
  • link — the connection to another account chain (send target or receive source)

The link field's meaning depends on the block's implied action:

Action determined by link contains
Balance decreases (send) Destination account public key
Balance increases (receive/open) Hash of the source send block
Balance unchanged (change rep) 0000...0000

The Ledger

All account chains together form the ledger — Kakitu's global state. The ledger is stored as a key-value database (LMDB) on every full node.

The ledger contains: - All confirmed blocks, indexed by hash - The current frontier (latest block) of each account - Confirmation height for each account (highest confirmed block) - Receivable entries (confirmed sends that haven't been received yet) - Vote records and representative weights

Double-Spend Prevention

Because each account chain is sequential, double-spending is structurally difficult:

  • An account can only have one valid frontier block at a time
  • If two conflicting blocks are broadcast for the same account (a fork), representatives vote on which one to confirm
  • The losing fork is rejected by the network
  • Once a block is cemented (confirmed and recorded locally as irreversible), it cannot be undone

Comparison to Traditional Blockchains

Property Traditional Blockchain Kakitu Block Lattice
Global order of transactions Required Not required
Transaction throughput Limited by block size Scales with accounts
Transaction fees Required (to prioritize in block) Not required
Finality Probabilistic (reorgs possible) Deterministic (ORV quorum)
Orphan blocks Common Not applicable