IsccNote Protocol Schema¶

An ISCC Declaration record submitted to an ISCC-HUB for timestamping and registration. IsccNote is the permanent, self-describing log entry that binds an ISCC-CODE to its content hashes and a cryptographic signature. Stored in an append-only log, declarations are immutable once accepted, so the record is version-pinned and carries resolvable schema and context URLs.

JSON Schema: iscc-note.json

Minimal declaration

{
  "$schema": "http://purl.org/iscc/schema/iscc-note-0.7.0.json",
  "iscc_code": "ISCC:KACYPXW445FTYNJ3CYSXHAFJMA2HUWULUNRFE3BLHRSCXYH2M5AEGQY",
  "datahash": "1e20253d0f3460085c276f038de345c8e953a306f4a07f9fa77f5af8563c3d7274c5",
  "nonce": "0013a3c214c05796673503e6e549446d",
  "signature": {
    "version": "ISCC-SIG v1.0",
    "controller": "did:web:example.com",
    "pubkey": "z6MkmeDbeC5BecFmVnTHA5PWEBaVUrGLdB3weGE2KYnXfHso",
    "proof": "z5j9nrpPw3oYSAN4XbCvk2sUtkwrueTD6V2Y35gS1KFTode2ED2YQWokPmoXw6QBYtYEFxtAQfzBhdNyr8PMwP79G"
  }
}

Complete declaration (all fields)

{
  "$schema": "http://purl.org/iscc/schema/iscc-note-0.7.0.json",
  "iscc_code": "ISCC:KACYPXW445FTYNJ3CYSXHAFJMA2HUWULUNRFE3BLHRSCXYH2M5AEGQY",
  "datahash": "1e20253d0f3460085c276f038de345c8e953a306f4a07f9fa77f5af8563c3d7274c5",
  "nonce": "0013a3c214c05796673503e6e549446d",
  "timestamp": "2025-08-12T14:30:00.123Z",
  "signature": {
    "version": "ISCC-SIG v1.0",
    "controller": "did:web:example.com",
    "keyid": "key-1",
    "pubkey": "z6MkmeDbeC5BecFmVnTHA5PWEBaVUrGLdB3weGE2KYnXfHso",
    "proof": "z5j9nrpPw3oYSAN4XbCvk2sUtkwrueTD6V2Y35gS1KFTode2ED2YQWokPmoXw6QBYtYEFxtAQfzBhdNyr8PMwP79G"
  },
  "units": [
    "ISCC:IADSKPIPGRQAQXBHN4BY3Y2FZDUVHIYG6SQH7H5HP5NPQVR4HVZHJRI",
    "ISCC:GADUCK27AIQUBLC3ALIINORUJ6JEC4GHRWXSXLIO5VLKRE65RM6A5RI",
    "ISCC:AADWN77F727NXSUSUVDFOUS64JFPMZ4GAR5NJ3O5P563LTMXWS5XNSQ"
  ],
  "metahash": "1e208bad08ad56b5517e09bc8bc5e2281b2d8f21d096939a310f539cf5007d443772",
  "gateway": "https://gateway.example.com/declaration/{iscc_id}"
}

Required fields: $schema, iscc_code, datahash, nonce, signature

Field Reference¶

@context¶

Name	Type	Default	Definition
@context	`string-uri`	http://purl.org/iscc/context	The JSON-LD Context URI for ISCC metadata.

@type¶

Name	Type	Default	Definition
@type	`string`	IsccNote	The type of protocol metadata.

$schema¶

Name	Type	Default	Definition
$schema	`string-uri`	http://purl.org/iscc/schema/iscc-note-0.7.0.json	The JSON Schema URI for ISCC Declaration metadata.

iscc_code¶

Name	Type	Default	Definition
iscc_code	`string`	none	The ISCC-CODE identifying the digital content being declared. Mapped to JSON-LD @id, making it the RDF subject of the declaration. Supports full-length 256-bit ISCC-CODEs. Example: `ISCC:KACYPXW445FTYNJ3CYSXHAFJMA2HUWULUNRFE3BLHRSCXYH2M5AEGQY`

datahash¶

http://purl.org/iscc/terms/#datahash

Name	Type	Default	Definition
datahash	`string`	none	A blake3 multihash of the digital content, hex-encoded with the `1e20` multihash prefix (blake3, 32-byte digest). Binds the declaration to the exact content bytes. Example: `1e20253d0f3460085c276f038de345c8e953a306f4a07f9fa77f5af8563c3d7274c5`

nonce¶

http://purl.org/iscc/terms/#nonce

Name	Type	Default	Definition
nonce	`string`	none	Cryptographic nonce for replay protection. A 128-bit random value encoded as lowercase hexadecimal. Example: `0013a3c214c05796673503e6e549446d`

timestamp¶

http://purl.org/iscc/terms/#timestamp

Name	Type	Default	Definition
timestamp	`string`	none	RFC 3339 timestamp of declaration creation in UTC with millisecond precision. Optional on submission - an ISCC-HUB assigns the authoritative timestamp on receipt. Example: `2025-08-12T14:30:00.123Z`

signature¶

http://purl.org/iscc/terms/#signature

Name	Type	Default	Definition
signature	`object`	none	Cryptographic signature over the IsccNote, conforming to the iscc-crypto signing protocol. Uses EdDSA (Ed25519) with JCS canonicalization.

units¶

http://purl.org/iscc/terms/#units

Name	Type	Default	Definition
units	`array`	none	The individual full-length ISCC-UNITs that compose the declared ISCC-CODE, enabling similarity matching against the declaration. One to four 256-bit ISCC-UNITs. Example: `['ISCC:IADSKPIPGRQAQXBHN4BY3Y2FZDUVHIYG6SQH7H5HP5NPQVR4HVZHJRI']`

metahash¶

http://purl.org/iscc/terms/#metahash

Name	Type	Default	Definition
metahash	`string`	none	A blake3 multihash of the seed metadata, hex-encoded with the `1e20` multihash prefix (blake3, 32-byte digest). Same format as `datahash`. Example: `1e208bad08ad56b5517e09bc8bc5e2281b2d8f21d096939a310f539cf5007d443772`

gateway¶

http://purl.org/iscc/terms/#gateway

Name	Type	Default	Definition
gateway	`string`	none	An HTTP(S) URL or RFC 6570 URI template of a gateway that serves metadata for the declared ISCC. Used by ISCC resolvers to discover content metadata. Example: `https://gateway.example.com/declaration/{iscc_id}`