SHA-256 Hashing

Roadmap — vision layer

The StreetLedger public hashing surface is design intent. The canonicalization principle on this page is real and is exactly what the shipped systems already do — see the two live code paths below.

The principle

JSON canonicalization: sorted keys · no whitespace · UTF-8 encoding. SHA-256 over the canonical bytes. If the hash depended on key ordering, whitespace, or encoding choice the proof would break — two parties computing the hash from the same JSON must always get the same answer. Otherwise the chain-of-title is fiction.

The real, shipped code paths

This exact discipline ships in production today in two places:

• DefendableCloud (api/app/hashing.py, used by api/app/ledger.py): canonical JSON via orjson.dumps(obj, option=orjson.OPT_SORT_KEYS), then sha256_hex(canonical(payload)). This is what backs the per-org DCR-* hash chain at /ledger + /ledger/verify.
• DefendableRouter (core/pricing.py / receipt writer): canonical JSON with sort_keys, fixed separators, Decimal rendered to 2-decimal strings, and ISO timestamps — hashed into checksum_sha256 for each JSONL receipt line (checksummed, not chained).

Why determinism matters

Same algorithm · same output · every time. A buyer, a regulator, or a model can recompute the hash from the canonical JSON and get the same 64 characters the issuer stamped — no trust required, no round-trip required.

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🐝 Operator-grade · books and records · to the shed.