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Blocks

All Kakitu transactions use the state block format. Every action — sending, receiving, changing a representative — is represented as a single state block on an account's chain.

State Block Format

{
  "type": "state",
  "account": "kshs_3t6k35gi95xu6tergt6p69ck76ogmitsa8mnijtpxm9fkcm736xtoncuohr3",
  "previous": "A170D51B94E00371ACE76E35AC81DC9405D5D04D4CEBC399AEACE07AE05DD293",
  "representative": "kshs_1kakituxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
  "balance": "990000000000000000000000000000",
  "link": "E89208DD038FBB269987689621D52292AE9C35941A7484756ECCED92A65093BA",
  "link_as_account": "kshs_3t6k35gi95xu6tergt6p69ck76ogmitsa8mnijtpxm9fkcm736xtoncuohr3",
  "signature": "SIGNATURE_HEX",
  "work": "WORK_HEX"
}

Field Definitions

type

Always "state". All blocks in the modern Kakitu protocol use this type.

account

The kshs_ address of the account that owns this block. This is whose chain the block belongs to.

previous

The hash of the immediately preceding block in this account's chain.

For the first block (open block), previous is all zeros:

0000000000000000000000000000000000000000000000000000000000000000

representative

The kshs_ address of the representative for this account. The representative's balance weight is counted from this account.

You can change your representative at any time by creating a new block with a different representative value and the same balance (no funds move).

balance

The account's balance after this block executes, in raw (integer, not floating-point).

1 KSHS = 1000000000000000000000000000000 raw

A 32-byte hex field whose meaning depends on the block action:

Action Determined by link value
Send balance decreases Destination account's public key
Receive / Open balance increases Hash of the source send block
Change representative balance unchanged 0000...0000 (64 zeros)

signature

An Ed25519 signature of the block hash, signed with the account's private key. This proves the account owner authorized the block.

See Signing & Hashing for the signing procedure.

work

The Proof-of-Work value for this block. Must satisfy the minimum difficulty threshold for the block type.

See Work for the PoW algorithm.

Block Hash

The block hash is a Blake2b-256 hash of the block contents. It is computed before signing:

hash = blake2b_256(
  block_hash_preamble ||  // 32-byte constant: 0x6...
  account_public_key   ||  // 32 bytes
  previous_hash        ||  // 32 bytes
  representative_pubkey||  // 32 bytes
  balance              ||  // 16 bytes (128-bit big-endian)
  link                     // 32 bytes
)

The signature is computed over this hash.

Block Types (Historical)

Prior to the state block format, Kakitu (and Nano) used separate block types for each action:

Legacy Type Replaced by
send State block (balance decreases)
receive State block (balance increases)
open State block (first block in chain)
change State block (representative only)

All blocks on the current network use the state format. Legacy types may appear in historical data.

Example: Send Block

Account A sends 1 KSHS to Account B:

{
  "type": "state",
  "account": "kshs_ACCOUNT_A",
  "previous": "LAST_BLOCK_HASH_ON_A",
  "representative": "kshs_REPRESENTATIVE",
  "balance": "9000000000000000000000000000000",
  "link": "PUBLIC_KEY_OF_ACCOUNT_B",
  "signature": "SIGNATURE",
  "work": "WORK"
}

Account B's balance before: 0 KSHS, Account A's balance before: 10 KSHS. After this block: A has 9 KSHS, the 1 KSHS is receivable by B.

Example: Receive Block

Account B receives the 1 KSHS sent by Account A:

{
  "type": "state",
  "account": "kshs_ACCOUNT_B",
  "previous": "LAST_BLOCK_HASH_ON_B",
  "representative": "kshs_REPRESENTATIVE",
  "balance": "1000000000000000000000000000000",
  "link": "HASH_OF_THE_SEND_BLOCK",
  "signature": "SIGNATURE",
  "work": "WORK"
}

After confirmation: B has 1 KSHS.

Broadcasting a Block

Once a block is built and signed, broadcast it via the process RPC:

curl -s -d '{
  "action": "process",
  "json_block": "true",
  "subtype": "send",
  "block": {
    "type": "state",
    "account": "kshs_ACCOUNT_A",
    "previous": "PREV_HASH",
    "representative": "kshs_REP",
    "balance": "9000000000000000000000000000000",
    "link": "DESTINATION_PUBLIC_KEY",
    "signature": "SIGNATURE",
    "work": "WORK"
  }
}' http://localhost:7076

The subtype field (send, receive, open, change, epoch) helps the node validate the block correctly.