Block format¶

A Navio block is a Bitcoin-shaped block with BLSCT-aware transaction bodies.

CBlockHeader (80 bytes)
├── nVersion            int32
├── hashPrevBlock       32 bytes
├── hashMerkleRoot      32 bytes
├── nTime               uint32
├── nBits               uint32    compact difficulty target
└── nNonce              uint32    Header nonce (legacy Bitcoin field; PoPS proof lives in block.posProof, not here)

Identical to Bitcoin at the byte level. All BLSCT / PoPS blocks use the same 80-byte header shape. Consensus-critical data that cannot fit in the header (the ZK proof itself) lives in block.posProof, appended outside the header.

Block body¶

CBlock
├── Header              80 bytes
├── posProof            blsct::ProofOfStake (set-membership + range proof)
├── vtx[]               CTransaction[]
│   ├── vtx[0]          Coinbase (zero-value output)
│   ├── vtx[1]          Coinstake (zero-value marker output, then reward outputs)
│   └── vtx[2..]        Regular BLSCT transactions
└── witness commitment  embedded in coinbase if any segwit-style fields used

Field order per primitives/block.h: READWRITE(obj.posProof, obj.vtx) after the header.

Coinbase¶

The first transaction is the coinbase. Its single output is zero-value; the real staker reward is paid in the coinstake. vin[0].prev_out is the null marker (32 zero bytes).

During the bootstrap PoW window (heights 2..110 on mainnet), the zero-value coinbase output still carries a full Bulletproofs+ range proof and BLSCT keys — the miner constructs it with fAllowZeroValueRangeProof = true.

Why a range proof on a zero-value coinbase

Normally CreateOutput() collapses a 0 amount into an unspendable OP_RETURN with no range proof. But the coinbase still carries balance and output signatures that are folded into the block's aggregate signature check — an OP_RETURN output (no range proof, no keys) would have nothing to sign over and the aggregate verification would fail. Passing fAllowZeroValueRangeProof = true forces a proper BLSCT output so the signatures remain valid.

The block-1 coinbase mints the entire initial supply.

Coinstake (PoPS)¶

Every block carries a blsct::ProofOfStake posProof field (see primitives/block.h). Structural markers:

vtx[0] (coinbase) — null prev_out, zero-value output
vtx[1] (coinstake) — first output is zero-value nonstandard marker
block.posProof — encoded ZK proof (set-membership + range proof)

Key points about PoPS — applies to the current BLSCT networks (mainnet, testnet, and blsctregtest):

posProof does not identify the staker's locked UTXO. It contains a set-membership proof over the current staked-commitment set plus a range proof binding a hidden stake amount to the block's kernel-hash eligibility threshold.
Eligibility is verifiable with zero-knowledge — no validator identity, amount, or cross-block linkage is revealed.
Coinstake outputs pay the network's current PoPS subsidy plus returned principal as BLSCT outputs addressed to sub-addresses in the staker's staking pool (account -2).

Full math, verifier equations, serialisation, source-tree map: BLSCT → Proof-of-Private-Stake.

Fee handling¶

Source	Fate
Regular BLSCT transaction fees	Burned
OP_RETURN outputs	Burned — provably unspendable
Community fund (legacy Navcoin at mainnet genesis)	Burned
Staking rewards earned on migrated supply during swap window	Burned

See Consensus for the full economic picture.

Merkle commitment¶

Standard Bitcoin-style Merkle tree of transaction hashes, committed to in the header. BLSCT transactions hash via their canonical serialised form including BLSCT-specific fields.

Block explorer view¶

The navio-blocks indexer categorises blocks via:

block.type = "PoPS"  # on BLSCT / PoPS chains

BLSCT-aware outputs display as Hidden amounts. Transparent outputs (genesis-time bootstrap outputs that seed the PoPS staker set on testnet cuts, and OP_RETURN burns) show values normally. See supply tracking.

Genesis block (mainnet)¶

The mainnet genesis block (height 0) is a plain unspendable OP_RETURN coinbase — not a BLSCT output. There is no range proof or BLSCT keys, because the genesis block is never connected to the UTXO set: ConnectBlock() in validation.cpp special-cases the genesis hash and returns early, so no spendable BLSCT output is ever needed.

Field	Value
Block hash	`0af3c23ae1ac4910693b7187ac61641d16d1cf49cba7acf8649d48e831d86b13`
Merkle root	`96f8dfcc3c433012bc9d4b42e85fe543936609f87fce2cc9d5484383ee2f9aaf`
`nTime`	`1782910800` (2026-07-01 13:00 UTC)
`nNonce`	`0`
`nBits`	`0x207fffff`
`nVersion`	`0x40000000` (BLSCT version bit)

The coinbase scriptSig embeds a hidden message:

Privacy is the power to selectively reveal oneself to the world.

Both nMinimumChainWork and defaultAssumeValid are zero — this is a fresh chain with no checkpointed history.

Serialisation¶

src/primitives/block.h — CBlock, CBlockHeader.
src/blsct/pos/ — PoS / PoPS consensus rules.
src/consensus/params.h — chain-level constants (block time, max size, activation heights).

Current chainparams: mainnet uses a bootstrap PoW window through height 110 (PoPS from height 111), then PoPS with nPosTargetSpacing = 120 and nBLSCTBlockReward = 8 NAV; testnet uses a bootstrap PoW window through height 1000, then PoPS with nPosTargetSpacing = 60 and nBLSCTBlockReward = 4 NAV.