Cardano-anchored DSSE blood ledger

Batch a set of DSSE Khipu receipts into a Merkle root and anchor that root as Cardano transaction metadata — a public, immutable timestamp for your governance "blood ledger."

Headline number: N receipts → 1 Merkle root → 1 on-chain metadatum.

The memory cortex (the a11oy Memory role, inside a11oy) calls its receipt chain the yawar (blood) ledger. Anchoring its Merkle root on Cardano L1 gives an independent, public proof-of-existence. This is hash anchoring only — not a token, not custodial, not a transfer of value.

HONEST PREREQUISITE — READ FIRST. a11oy's live /v1/honest states: "Cardano-anchored receipts are demo-seeded, not on-chain mainnet." Mainnet (and even funded testnet) submission requires founder credentials (a funded wallet + signing keys). This recipe therefore has two paths:

1. Demo path (no credentials) — build and verify the Merkle root + the metadata payload locally. Fully runnable here.
2. Testnet path (requires a funded Cardano preprod wallet) — submit the root and retrieve the proof. Clearly gated below.

---

Prerequisites

python3 -m pip install requests          # demo path
# Testnet path additionally needs: cardano-cli OR a Blockfrost preprod project_id,
# and a funded preprod wallet. These are FOUNDER-PROVIDED credentials.

---

Quickstart — demo path (no credentials)

import hashlib, json, urllib.request

LAKE = "https://huggingface.co/datasets/SZLHOLDINGS/szl-lake/resolve/main"
lines = urllib.request.urlopen(f"{LAKE}/khipu/a11oy_receipts.ndjson", timeout=30).read().splitlines()
leaves = [hashlib.sha256(l).digest() for l in lines if l.strip()]

def merkle_root(leaves):
    if not leaves: return b"\x00" * 32
    layer = leaves
    while len(layer) > 1:
        if len(layer) % 2: layer = layer + [layer[-1]]            # duplicate last
        layer = [hashlib.sha256(layer[i] + layer[i+1]).digest() for i in range(0, len(layer), 2)]
    return layer[0]

root = merkle_root(leaves).hex()
metadatum = {"674": {"msg": ["szl.khipu.anchor/v1", f"root:{root}",
                              "doctrine:v11", "kernel:c7c0ba17"]}}   # CIP-20 label 674
print("merkle_root:", root)
print("cardano_metadatum:", json.dumps(metadatum))

The 674 label is the CIP-20 transaction-message standard — the conventional home for arbitrary anchor strings.

---

Full walkthrough

Step 1 — Verify the receipts before you anchor

Anchoring a forged receipt just timestamps a forgery. Verify each receipt's signature first (recipe 01) so the Merkle root commits to authentic receipts only.

Step 2 — Build a stable, ordered Merkle tree

Sort receipts by (seq, receipt_id) so the root is deterministic and reproducible by an auditor. Record the leaf order alongside the root.

Step 3 — Form the metadata payload

Keep each metadata string ≤ 64 bytes (Cardano metadata constraint). Split the root across two strings if needed, or store root plus a pointer to the leaf-order file in the lake.

Step 4 (gated) — Submit to Cardano preprod testnet

Requires a funded preprod wallet — founder credentials.

# Example with cardano-cli (preprod). Wallet keys are founder-supplied; never commit them.
cardano-cli transaction build \
  --testnet-magic 1 \
  --tx-in "$UTXO" --change-address "$ADDR" \
  --metadata-json-file metadatum.json \
  --out-file tx.raw
cardano-cli transaction sign --tx-body-file tx.raw --signing-key-file payment.skey \
  --testnet-magic 1 --out-file tx.signed
cardano-cli transaction submit --tx-file tx.signed --testnet-magic 1

Step 5 — Retrieve the proof

After confirmation, the transaction hash is the proof. Resolve it on a preprod explorer or via Blockfrost:

curl -s -H "project_id: $BLOCKFROST_PREPROD" \
  "https://cardano-preprod.blockfrost.io/api/v0/txs/$TXHASH/metadata" | jq .

Store {merkle_root, leaf_order_url, tx_hash, network: "preprod"} back in the lake as the anchor receipt — itself verifiable by recipe 01.

---

See also

• 01 — Verify a receipt end-to-end — verify before anchoring.
• 05 — Memory-attested reasoning — the chain you're anchoring.
• Live: a11oy (hosts the a11oy Memory) · CIP-20

Cite this recipe

@misc{szl_cookbook_cardano_anchor_2026,
  title        = {Cardano-anchored DSSE blood ledger (SZL Cookbook recipe 10)},
  author       = {{SZL Holdings}},
  year         = {2026},
  howpublished = {\url{https://github.com/szl-holdings/szl-cookbook/blob/main/recipes/10-cardano-dsse-blood-ledger.md}},
  note         = {Hash anchoring only; mainnet/testnet submission needs founder credentials. Demo path needs none.}
}

---

Doctrine v11 LOCKED — 749/14/163 — kernel c7c0ba17 · Λ = Conjecture 1 · SLSA L1 (honest)