Proof of work

Parano1d proof of work is a domain-separated Poseidon2b digest over the fixed semantic header fields. It runs after the nonce-independent HistoryStep has been proved.

Field schedule

The POWHDR__ sponge absorbs exactly 16 GF(2^128) elements:

Thirty-two-byte values are split into two little-endian 128-bit halves. Scalar integers are zero-extended. With sponge rate two, the schedule is exactly eight rate blocks and needs no variable-length padding.

The PoW domain differs from both nonce-bearing block identity and the nonce-free semantic header commitment.

Target comparison

The digest and target are interpreted as 256-bit little-endian integers. A nonce is valid only when:

pow_digest < difficulty_target

Equality fails.

ASERT

The target block interval is 15 seconds. ASERT uses a six-block reference epoch and a 90-second half-life. At each height, validation derives the exact target from the canonical anchor, elapsed time and height delta.

A timestamp must also be greater than median time past over the previous 11 headers and no more than 120 seconds ahead of the validating node's wall clock.

Runtime kernels

The same fixed permutation is evaluated in packed nonce batches. The production binary selects the best supported implementation at runtime:

• PCLMULQDQ baseline on x86-64;
• AVX2 with VPCLMULQDQ where available;
• AVX-512 on supported hosts;
• NEON with PMULL on ARM64.

Packed execution changes throughput, not the digest. The scalar implementation is a test oracle and is not a production fallback.

External mining boundary

An external worker receives the exact 16-field schedule, nonce index and target. It returns only a canonical 16-byte little-endian nonce. The node checks it against the immutable, single-use template before committing a block.

The worker cannot alter a transaction, State root, payout or proof. A solved nonce for an expired or stale template is rejected.