§ Decentralized Web Node

Specification Status: Draft

Latest Draft: identity.foundation/decentralized-web-node/spec

Previous Draft: 0.0.1-predraft

Editors:
Daniel Buchner (Block)
Tobias Looker (Mattr)
Contributors:
Henry Tsai (Microsoft)
XinAn Xu (Microsoft)
Moe Jangda (Block)
Participate:
GitHub repo
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§ Abstract

Most digital activities between people, organizations, devices, and other entities require the exchange of messages and data. For entities to exchange messages and data for credential, app, or service flows, they need an interface through which to store, discover, and fetch data related to the flows and experiences they are participating in. A Decentralized Web Node (DWN) is a data storage and message relay mechanism entities can use to locate public or private permissioned data related to a given Decentralized Identifier (DID). Decentralized Web Nodes are a mesh-like datastore construction that enable an entity to operate multiple nodes that sync to the same state across one another, enabling the owning entity to secure, manage, and transact their data with others without reliance on location or provider-specific infrastructure, interfaces, or routing mechanisms.

§ Status of This Document

Decentralized Web Node is a DRAFT specification under development within the Decentralized Identity Foundation (DIF). It is an active work item of the Secure Data Storage Working Group at DIF. It incorporates requirements and learnings from related work of many active industry players into a shared specification that meets the collective needs of the community.

The specification will be updated to incorporate feedback, from DIF members and the wider community, with a reference implementation being developed within DIF that exercises the features and requirements defined here. We encourage reviewers to submit GitHub Issues as the means by which to communicate feedback and contributions.

§ Terminology

Decentralized Web Node
A decentralized personal and application data storage and message relay node, as defined in the DIF Decentralized Web Node specification. Users may have multiple Nodes that replicate their data between them.
Decentralized Identifiers
Unique ID URI string and PKI metadata document format for describing the cryptographic keys and other fundamental PKI values linked to a unique, user-controlled, self-sovereign identifier in a target system (e.g., blockchain, distributed ledger).

§ Topology

§ Technical Stack

Decentralized Web Nodes are comprised of the following component layers, each of which is defined in this specification to ensure multiple Decentralized Web Node implementations can be used together and operate as a single logical unit for users.

DID Authentication
Access & Authorization
Interface Definitions
Interface-Specific Processing
Object Format
Object Signing / Encryption
IPLD Multiformats

§ Service Endpoints

The following DID Document Service Endpoint entries MUST be present in the DID Document of a target DID for DID-relative URL resolution to properly locate the URI for addressing a DID owner’s Decentralized Web Nodes:

{
  "id": "did:example:123",
  "service": [{
    "id":"#dwn",
    "type": "DecentralizedWebNode",
    "serviceEndpoint": {
      "nodes": ["https://dwn.example.com", "https://example.org/dwn"]
    }
  }]
}

§ Addressing

A user’s Decentralized Web Nodes can be addressed in many ways, but the mechanisms below MUST be supported by a compliant Decentralized Web Node implementation:

§ DID-Relative URLs

The following DID URL constructions are used to address Decentralized Web Nodes found to be associated with a given DID, as located via the DID resolution process.

§ Composition

The following process defines how a DID-Relative URL is composed to address a Decentralized Web Node:

  1. Let the base URI authority portion of the DID URL string be the target DID being addressed.
  2. Append a service parameter to the DID URL string with the value DecentralizedWebNode.
  3. Assemble an array of the Message Descriptor objects as desired for encoding in the DID-relative URL
  4. JSON stringify the array of Message Descriptor objects from Step 3, then Base64Url encode the stringified output.
  5. Append a queries parameter to the DID URL string with the value set to the JSON stringified, Base64Url encoded output of Step 4.

DID-relative URLs are composed of the following segments

did:example:123 + ?service=DecentralizedWebNode + &queries= + toBase64Url( JSON.stringify( [{ DESCRIPTOR_1 }, { DESCRIPTOR_N }] ) )

did:example:123?service=DecentralizedWebNode&queries=W3sgTUVTU0FHRV8xIH0sIHsgTUVTU0FHRV9OIH1d...

§ Resolution

The following process defines how a DID-Relative URL for a Decentralized Web Node is resolved:

  1. Resolve the DID in the authority portion of the URL in accordance with the W3C Decentralized Identifier Resolution process, which returns the DID Document for the resolved DID.
  2. As indicated by the presence of the service parameter, locate the DecentralizedWebNode entry in the DID Document’s Service Endpoint entries.
  3. Parse the DecentralizedWebNode Service Endpoint object and select the first URI present in the serviceEndpoint objects nodes array. NOTE: implementers SHOULD select from the URIs in the nodes array in index order.
  4. If the URI located in step 3 is not a DID URI, proceed to step 5. If the URI from step 3 is a DID, resolve the DID and follow steps 2 and 3 to select the first URI in the DID’s DecentralizedWebNode Service Endpoint object nodes array that is not a DID URI. Do not iterate this loop more than once - if a non-DID URI cannot be located after one loop of recursive resolution, terminate resolution and produce an error.
  5. Assuming a non-DID URI was located in steps 2-4, let the located URI be the base URI of the Decentralized Web Node request being constructed.

§ Request Construction

DID-Relative URL example for passing multiple messages:

NOTE

For example purposes, the queries parameter value below is neither JSON stringified nor Base64Url encoded, but should be when using Decentralized Web Node URLs in practice (see the DID-relative URL Composition instructions above).

did:example:123?service=DecentralizedWebNode&queries=[{ "method": "CollectionsQuery", "schema": "https://schema.org/SocialMediaPosting" }]

did:example:123?service=DecentralizedWebNode&queries=W3sgTUVTU0FHRV8xIH0sIHsgTUVTU0FHRV9OIH1d...

Resolve DID to locate its Decentralized Web Node URIs:

did:example:123 --> resolve to Decentralized Web Node endpoint(s) --> https://dwn.example.com/

Construct the Request Object:

  1. Create a JSON object for the request.
  2. The Request Object MUST include a messages property, and its value MUST be an array composed of Message objects that are generated by parsing the DID-relative URL’s queries parameter value as a JSON array and performing the following steps for each entry:
    1. Construct a Message object.
    2. Set the descriptor property of the Message object to the entry, ensuring it is a valid Message Descriptor object.
    3. Set the processing property of the Message object to the entry, ensuring it is a valid Message Processing object.
    4. Augment the Message object with any signing and authorization values required, as described in the Messages section.
    5. Append the object to the Request Object’s messages array.

HTTP POST example:

POST https://dwn.example.com/

BODY {
  "messages": [
    {
      "descriptor": {
        "method": "CollectionsQuery",
        "schema": "https://schema.org/SocialMediaPosting"
      },
      "processing": {
        "nonce": "4572616e48616d6d65724c61686176",
        "author": "did:example:alice",
        "recipient": "did:example:bob",
      }
    },
    {...}
  ]
}

§ Request Objects

Request Objects are JSON object envelopes used to pass messages to Decentralized Web Nodes.

{  // Request Object
  "messages": [  // Message Objects
    {...},
    {...},
    {...}
  ]
}

Request Objects are composed as follows:

  1. The Request Object MUST include a messages property, and its value MUST be an array composed of Message objects.

§ Messages

All Decentralized Web Node messaging is transacted via Messages JSON objects. These objects contain message execution parameters, authorization material, authorization signatures, and signing/encryption information. For various purposes Messages rely on IPFS CIDs and DAG APIs.

{  // Request Object
  "messages": [  // Message Objects
    {
      "recordId": GENERATED_CID_STRING,
      "data": BASE64URL_STRING,
      "descriptor": {
        "method": INTERFACE_METHOD_STRING,
        "dataCid": DATA_CID_STRING,
        "dataFormat": DATA_FORMAT_STRING,
      },
      "processing": {
        "nonce": "4572616e48616d6d65724c61686176",
        "author": "did:example:alice",
        "recipient": "did:example:bob",
      }
    },
    {...}
  ]
}

Messages objects MUST be composed as follows:

In order to enable data replication features for a Decentralized Web Node, all Messages MUST be committed to an IPFS DAG in a tree allocated to the DID of the owner after all subtrees are composed and committed. The top-level of Message objects MUST be committed as a DAG CBOR encoded object.

NOTE

Individual Interface methods may describe additional properties that the descriptor object MUST or MAY contain, which are detailed in the Interfaces section of the specification.

§ Message Authorization

Some messages may require authorization material for processing them in accordance with the permissions a Decentralized Web Node owner has specified. If a message requires authorization it MUST include an authorization property with a value that is a [RFC7515] General JSON Web Signature (JWS), constructed as follows:

{  // Request Object
  "messages": [  // Message Objects
      "data": "bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi",
      "recordId": "b65b7r8n7bewv5w6eb7r8n7t78yj7hbevsv567n8r77bv65b7e6vwvd67b6",
      "descriptor": {
        "method": "CollectionsWrite",
        "schema": "https://schema.org/SocialMediaPosting",
        "dataCid": CID(data),
        "dateCreated": 123456789,
        "dataFormat": "application/json"
      },
      "processing": {
        "nonce": "4572616e48616d6d65724c61686176",
        "author": "did:example:alice",
        "recipient": "did:example:bob",
      },
      "attestation": {
        "payload": "89f5hw458fhw958fq094j9jdq0943j58jfq09j49j40f5qj30jf",
        "signatures": [{
          "protected": "4d093qj5h3f9j204fq8h5398hf9j24f5q9h83402048h453q",
          "signature": "49jq984h97qh3a49j98cq5h38j09jq9853h409jjq09h5q9j4"
        }]
      },
      "authorization": {
        "payload": "bafybeigdyrzt5sfp7udm7hu76uh7y26nf3efuylqabf3oclgtqy55fbzdi",
        "signatures": [{
          "protected": "f454w56e57r68jrhe56gw45gw35w65w4f5i54c85j84wh5jj8h5",
          "signature": "5678nr67e56g45wf546786n9t78r67e45657bern797t8r6e5"
        }]
      }
    },
    {...}
  ]
}

§ Raw Data

If there is no need or desire to sign or encrypt the content of a message (i.e. public repudiable data), the message descriptor object is the only property required in a Message (with any method-specific properties required). An optional data property may be passed at the Message level that contains the data associated with the message (when data is desired or required to be present for a given method invocation).

{ // Message
  "data": BASE64URL_STRING,
  "recordId": "b65b7r8n7bewv5w6eb7r8n7t78yj7hbevsv567n8r77bv65b7e6vwvd67b6",
  "descriptor": {
    "method": "CollectionsWrite",
    "schema": "https://schema.org/InviteAction",
    "dataCid": CID(data),
    "dateCreated": 123456789,
    "dataFormat": "application/json"
  },
  "processing": {
    "nonce": "4572616e48616d6d65724c61686176",
    "author": "did:example:alice",
    "recipient": "did:example:bob",
  }
}

§ Signed Data

If the object is to be attested by a signer (e.g the Node owner via signature with their DID key), the object MUST contain the following additional properties to produce a [RFC7515] General JSON Web Signature (JWS):

{ // Message
  "data": {...},
  "recordId": "b65b7r8n7bewv5w6eb7r8n7t78yj7hbevsv567n8r77bv65b7e6vwvd67b6",
  "descriptor": {
    "method": "CollectionsWrite",
    "schema": "https://schema.org/InviteAction",
    "dataCid": CID(data),
    "dateCreated": 123456789,
    "dataFormat": "application/json"
  },
  "processing": {
    "nonce": "4572616e48616d6d65724c61686176",
    "author": "did:example:alice",
    "recipient": "did:example:bob",
  },
  "attestation": {
    "payload": "89f5hw458fhw958fq094j9jdq0943j58jfq09j49j40f5qj30jf",
    "signatures": [{
      "protected": "4d093qj5h3f9j204fq8h5398hf9j24f5q9h83402048h453q",
      "signature": "49jq984h97qh3a49j98cq5h38j09jq9853h409jjq09h5q9j4"
    }]
  }
  ...
}

The message generating party MUST construct the signed message object as follows:

  1. The Message object MUST contain an attestation property, and its value MUST be a General object representation of a [RFC7515] JSON Web Signature composed as follows:
    • The object must include a payload property, and its value must be the stringified Version 1 CID of the DAG CBOR encoded descriptor object, whose composition is defined in the Message Descriptor section of this specification.
    • The object MUST include a protected property, and its value must be an object composed of the following values:
      • The object MUST include an alg property, and its value MUST be the string representing the algorithm used to verify the signature (as defined by the [RFC7515] JSON Web Signature specification).
      • The object MUST include a kid property, and its value MUST be a DID URL string identifying the key to be used in verifying the signature.
    • The object MUST include a signature property, and its value must be a signature string produced by signing the protected and payload values, in accordance with the [RFC7515] JSON Web Signature specification.

§ Encrypted Data

If the object is to be encrypted (e.g the Node owner encrypting their data to keep it private), the descriptor object MUST be constructed as follows:

{ // Message
  "data": { 
    "protected": ...,
    "recipients": ...,
    "ciphertext": ...,
    "iv": ...,
    "tag": ... 
  },
  "recordId": "b65b7r8n7bewv5w6eb7r8n7t78yj7hbevsv567n8r77bv65b7e6vwvd67b6",
  "descriptor": {
    "method": "CollectionsQuery",
    "schema": "https://schema.org/SocialMediaPosting"
  },
  "processing": {
    "nonce": "4572616e48616d6d65724c61686176",
    "author": "did:example:alice",
    "recipient": "did:example:bob",
  }
  ...
}

The message generating party MUST construct an encrypted message as follows:

  1. The encryption property of the descriptor object MUST be set to the string label value of a Supported Encryption Format.
  2. Generate an encrypted payload from the data conformant with the format specified in the encryption property…
  3. Generate a Version 1 CID from the payload produced in Step 2 and let the dataCid property of the descriptor object be the stringified representation of the CID.

§ Signed & Encrypted Data

If the object is to be both attributed to a signer and encrypted encrypted, it MUST be structured as follows:

{ // Message
  "data": { 
    "protected": ...,
    "recipients": ...,
    "ciphertext": ...,
    "iv": ...,
    "tag": ... 
  },
  "recordId": "b65b7r8n7bewv5w6eb7r8n7t78yj7hbevsv567n8r77bv65b7e6vwvd67b6",
  "descriptor": {
    "method": "CollectionsQuery",
    "schema": "https://schema.org/SocialMediaPosting"
  },
  "processing": {
    "nonce": "4572616e48616d6d65724c61686176",
    "author": "did:example:alice",
    "recipient": "did:example:bob",
  },
  "attestation": {
    "payload": "89f5hw458fhw958fq094j9jdq0943j58jfq09j49j40f5qj30jf",
    "signatures": [{
      "protected": "4d093qj5h3f9j204fq8h5398hf9j24f5q9h83402048h453q",
      "signature": "49jq984h97qh3a49j98cq5h38j09jq9853h409jjq09h5q9j4"
    }]
  },
}

The message generating party MUST construct the signed and encrypted message as follows:

  1. Follow the instructions described in the Encrypted Data section to add the required properties to the descriptor and produce a [RFC7516] JSON Web Encryption (JWE) object from the associated data.
  2. Follow the instructions described in the Signed Data section to add an attestation property with a General object representation of a [RFC7515] JSON Web Signature as its value.

§ Response Objects

Responses from Interface method invocations are JSON objects that MUST be constructed as follows:

  1. The object MAY have a status property if an error is produced from a general request-related issue, and if present its value MUST be an object composed of the following properties:
    • The status object MUST have a code property, and its value MUST be an integer set to the HTTP Status Code appropriate for the status of the response.
    • The status object MAY have a detail property, and if present its value MUST be a string that describes a terse summary of the status. It is recommended that the implementer set the message text to the standard title of the HTTP Status Code, when a title/message has already been defined for that code.
  2. The object MAY have a replies property, and if present its value MUST be an array containing Message Result Objects for all messages that were included in the initiating request object. The Message Result Objects MUST be put in the index order that matches the index of each result’s corresponding request message. Message Result Objects are constructed as follows:
    1. The object MUST have a status property, and its value MUST be an object composed of the following properties:
      • The status object MUST have a code property, and its value MUST be an integer set to the HTTP Status Code appropriate for the status of the response.
      • The status object MAY have a detail property, and if present its value MUST be a string that describes a terse summary of the status. It is recommended that the implementer set the message text to the standard title of the HTTP Status Code, when a title/message has already been defined for that code.
    2. The object MAY have a entries property if the message request was successful. If present, its value MUST be the resulting message entries returned from the invocation of the corresponding message.

§ Request-Level Status Coding

If any of the scenarios described in this section are encountered during general message processing, the implementation must include a request-level status property, and its value must be an object as defined below.

Target DID not found

If the DID targeted by a request object is not found within the Decentralized Web Node, the implementation MUST produce a request-level status with the code 404, and SHOULD use Target DID not found within the Decentralized Web Node as the status detail value.

Response Example:

EXAMPLE
{
  "status": {
    "code": 404,
    "detail": "Target DID not found within the Decentralized Web Node"
  }
}

General request-level processing errors

If a general request-level error in processing occurs that is not covered by one of the specific status cases above and prevent the implementation from correctly evaluating the request, the implementation MUST produce a request-level status with the code 500, and SHOULD use The request cannot not be processed as the status detail value.

Response Example:

EXAMPLE
{
  "status": {
    "code": 500,
    "detail": "The request could not be processed correctly"
  }
}

§ Message-Level Status Coding

If any of the scenarios described in this section are encountered during the processing of an individual message, the implementation must include a message-level status property, and its value must be an object as defined below.

Message succeeded for query/read-type interface that expects results

If a message is processed correctly and a set of result entries is expected, the implementation MUST include a message-level status object with its code property set to 200, and SHOULD use The message was successfully processed as the status detail value.

NOTE

If no results are found, the status remains 200, and the implementation MUST return an empty entries array.

Request Example:

{  // Request Object
  "messages": [  // Message Objects
    {
      "descriptor": {
        "method": "CollectionsQuery",
        "schema": "https://schema.org/SocialMediaPosting"
      }
    },
    ...
  ]
}

Response Example:

EXAMPLE
{
  "replies": [
    {
      "status": { "code": 200, "detail": "OK" },
      "entries": [...]
    }
  ]
}

Improperly constructed message

If a message is malformed or constructed with invalid properties/values, the implementation MUST include a message-level status object with its code property set to 400, and SHOULD use The message was malformed or improperly constructed as the status detail value.

Request Example:

{  // Request Object
  "messages": [  // Message Objects
    {
      "descriptorization": {
        "methodical": "CollectionsQuery",
        "schemata": "https://schema.org/SocialMediaPosting"
      }
    }
  ]
}

Response Example:

EXAMPLE
{
  "replies": [
    {
      "status": { "code": 400, "detail": "The message was malformed or improperly constructed" }
    }
  ]
}

Message failed authorization requirements

If a message fails to meet authorization requirements during processing, the implementation MUST include a message-level status object with its code property set to 401, and SHOULD use The message failed authorization requirements as the status detail value.

Request Example:

{  // Request Object
  "messages": [  // Message Objects
    { // Message
      "data": {...},
      "descriptor": {
        "recordId": "b6464162-84af-4aab-aff5-f1f8438dfc1e",
        "dataCid": CID(data),
        "dateCreated": 123456789,
        "method": "CollectionsWrite",
        "schema": "https://schema.org/SocialMediaPosting",
        "dataFormat": "application/json"
      }

      ^  `authorization` PROPERTY MISSING
    }
  ]
}

Response Example:

EXAMPLE
{
  "replies": [
    {
      "status": { "code": 401, "detail": "OK" }
    }
  ]
}

Interface is not implemented

If a message attempts to invoke an interface method that is not the implementation does not support, the implementation MUST include a message-level status object with its code property set to 501, and SHOULD use The interface method is not implemented as the status detail value.

Request Example:

{  // Request Object
  "messages": [  // Message Objects
    { // Message
      "data": {...},
      "descriptor": {
        "dataCid": CID(data),
        "method": "CollectionsWrite",
        "schema": "https://schema.org/LikeAction",
        "dataFormat": "application/json"
      }
    }
  ]
}

Response Example:

EXAMPLE
{
  "replies": [
    {
      "status": {
        "code": 501,
        "detail": "The interface method is not implemented"
      }
    }
  ]
}

Resource consumption limit exceeded

If the DWeb Node instance receiving the request has determined that the rate of resource consumption has exceeded its tolerances and cannot process the request, the instance MUST respond with the following status entry:

Response Example:

EXAMPLE
{
  "replies": [
    {
      "status": {
        "code": 429,
        "detail": "Resource consumption has exceeded tolerances"
      }
    }
  ]
}

§ Interfaces

§ Feature Detection

The Decentralized Web Node specification defines well-recognized Decentralized Web Node configurations to maximize interoperability (see Configurations), but implementers may wish to support a custom subset of the Interfaces and features. The Feature Detection interface is the means by which a Decentralized Web Node expresses support for the Interfaces and features it implements.

§ Data Model

A compliant Decentralized Web Node MUST produce a Feature Detection object defined as follows:

{
  "type": "FeatureDetection",
  "interfaces": { ... }
}
§ Properties & Values

The following properties and values are defined for the Feature Detection object:

§ Read

All compliant Decentralized Web Nodes MUST respond with a valid Feature Detection object when receiving the following request object:

{ // Message
  "descriptor": { // Message Descriptor
    "method": "FeatureDetectionRead"
  }
}

§ Collections

To maximize decentralized app and service interoperability, the Collections interface of Decentralized Web Nodes provides a mechanism to store data relative to shared schemas. By storing data in accordance with a given schema, which may be well-known in a given vertical or industry, apps and services can leverage the same datasets across one another, enabling a cohesive, cross-platform, cross-device, cross-app experience for users.

§ CollectionsQuery

CollectionsQuery messages are JSON objects that include general Message Descriptor properties and the following additional properties, which must be composed as follows:

Get a single object by its ID reference:

{ // Message
  "descriptor": {
    "method": "CollectionsQuery",
    "filter": {
      "recordId": "b6464162-84af-4aab-aff5-f1f8438dfc1e"
    }
  }
}

Get a objects of a given schema type:

{ // Message
  "descriptor": {
    "method": "CollectionsQuery",
    "filter": {
      "schema": "https://schema.org/MusicPlaylist"
    }
  }
}

Get all objects of a given schema type:

{ // Message
  "descriptor": {
    "method": "CollectionsQuery",
    "dateSort": "createdDescending",
    "filter": {
      "dataFormat": "image/gif"
    }
  }
}

§ CollectionsWrite

CollectionsWrite messages are JSON objects that include general Message Descriptor properties and the following additional properties, which must be composed as follows:

{ // Message
  "data": "...",
  "recordId": "b65b7r8n7bewv5w6eb7r8n7t78yj7hbevsv567n8r77bv65b7e6vwvd67b6",
  "descriptor": { // Message Descriptor
    "parentId": CID(PREVIOUS_DESCRIPTOR),
    "dataCid": CID(data),
    "dateCreated": 123456789,
    "published": true,
    "encryption": "jwe",
    "method": "CollectionsWrite",
    "schema": "https://schema.org/SocialMediaPosting",
    "commitStrategy": "json-merge",
    "dataFormat": DATA_FORMAT
  }
}

§ CollectionsCommit

{ // Message
  "data": {...},
  "recordId": "b65b7r8n7bewv5w6eb7r8n7t78yj7hbevsv567n8r77bv65b7e6vwvd67b6",
  "descriptor": { // Message Descriptor
    "method": "CollectionsCommit",
    "dataCid": CID(data),
    "parentId": CID(ANCESTOR_CID),
    "dateCreated": 123456789,
    "commitStrategy": "json-merge",
    "dataFormat": DATA_FORMAT
  }
}

CollectionsCommit messages are JSON objects that include general Message Descriptor properties and the following additional properties, which must be composed as follows:

§ CollectionsDelete

{ // Message
  "descriptor": { // Message Descriptor
    "method": "CollectionsDelete",
    "recordId": "b6464162-84af-4aab-aff5-f1f8438dfc1e"
  }
}

CollectionsDelete messages are JSON objects that include general Message Descriptor properties and the following additional properties, which must be composed as follows:

§ Computed Context IDs

TODO

Detail how IDs are computed for record contexts.

§ Retained Message Processing

Retained messages in the Collections interface are those that may be stored against the specific record they are associated with. Within the Collections interface the CollectionsWrite, CollectionsCommit, CollectionsDelete messages are among the set that may be retained to determine the history and current data state of a record. A conforming implementation MUST perform the following steps to process retained messages:

§ If the message is a CollectionsWrite:
  1. Generate the message’s Entry ID by performing the Record ID Generation Process.
    • IF the generated Entry ID matches the recordId value of the message it is the Initial Entry for a record, store the entry as the Initial Entry for the record if no Initial Entry exists and cease any further processing.
    • ELSE the message may be an overwriting entry for the record; continue processing.
  2. If a message is not the Initial Entry, its descriptor MUST contain a parentId to determine the entry’s position in the record’s lineage. If a parentId is present proceed with processing, else discard the record and cease processing.
  3. Ensure all immutable values from the Initial Entry remained unchanged if present in the inbound message. If any have been mutated, discard the message and cease processing.
  4. Retrieve the Latest Checkpoint Entry, which will be either the Initial Entry or the latest CollectionsDelete, and compare the parentId value of the inbound message to the Entry ID of the Latest Checkpoint Entry derived from running the Record ID Generation Process on it. If the values match, proceed with processing, if the values do not match discard the message and cease processing.
  5. If an existing CollectionsWrite entry linked to the Latest Checkpoint Entry is not present and the dateCreated value of the inbound message is greater than the Latest Checkpoint Entry, store the message as the Latest Entry and cease processing, else discard the inbound message and cease processing.
  6. If an exiting CollectionsWrite entry linked to the Latest Checkpoint Entry is present all of the following conditions must be true:
    • The dateCreated value of the inbound message is greater than the existing CollectionsWrite, or if the dateCreated values are the same, the Entry ID of the inbound message is greater than the existing entry when the Entry IDs of the two are compared lexicographically.
  7. If all of the following conditions for Step 6 are true, store the inbound message as the Latest Entry and discard the existing CollectionsWrite entry that was attached to the Latest Checkpoint Entry.
§ If the message is a CollectionsCommit:
  1. Retrieve the currently active CollectionsWrite entry for the recordId specified in the inbound CollectionsCommit message. If there is no currently active CollectionsWrite entry, discard the inbound message and cease processing.
  2. Ensure all immutable values from the Initial Entry remained unchanged if present in the inbound message. If any have been mutated, discard the message and cease processing.
  3. If the currently active CollectionsWrite does not have a commitStrategy value, or the value does not match the commitStrategy value specified in the inbound message, discard the message and cease processing.
  4. The parentId of the message MUST match the currently active CollectionsWrite message’s Entry ID or that of another CollectionsCommit that descends from it. If the parentId does not match any of the messages in the commit tree, discard the inbound message and cease processing.
  5. The inbound message’s entry dateCreated value is less than the dateCreated value of the message in the commit tree its parentId references, discard the message and cease processing.
  6. If all of the above steps are successful, store the message in relation to the record.
§ If the message is a CollectionsDelete:
  1. Ensure the record specified by the inbound message’s recordId exists. If it does not, discard the message and cease processing.
  2. Ensure all immutable values from the Initial Entry remained unchanged if present in the inbound message. If any have been mutated, discard the message and cease processing.
  3. Fetch the active CollectionsDelete entry that exists for the record. If no such entry is present, proceed to the next step. If an active CollectionsDelete entry for the record is present, the dateCreated value of the inbound message MUST be greater than the active CollectionsDelete entry; if it is not, discard the message and cease processing.
  4. Store the message as the Latest Checkpoint Entry, delete all messages back to the Initial Entry, including their data, and cease processing.

§ Protocols

DWeb Nodes are designed to act the substrate upon which a wide variety of decentralized applications and services can be written. With an interface like Collections alone, a DWeb Node owner and those they permission can write isolated records, but that alone is not enough to support and facilitate decentralized apps. Protocols introduces a mechanism for declaratively encoding an app or service’s underlying protocol rules, including segmentation of records, relationships between records, data-level requirements, and constraints on how participants interact with a protocol. With the DWeb Node Protocols mechanism, one can model the underpinning protocols for a vast array of use cases in a way that enables interop-by-default between app implementations that ride on top of them.

§ ProtocolsConfigure

ProtocolsConfigure messages are JSON objects that include general Message Descriptor properties and the following additional properties, which must be composed as follows:

{
  "method": "ProtocolsConfigure", // required
  "protocol": "identity.foundation/protocols/credential-issuance", // required
  "protocolVersion": "1.0.0", // required
  "definition": { PROTOCOL_DEFINITION_OBJ }, // optional
  "lastConfiguration": CID_OF_PREVIOUS_CONFIG, // required if previous exists
  "retainedRecords": CHAMP_OF_INCLUDED_ENTRIES // optional
}

§ Protocol Definitions

Protocol Definition objects are declarative rules within ProtocolConfigure messages that specify the types, relationships, and interactions that are permitted under a given protocol installed in a DWeb Node. Inbound callers who wish to interact with a protocol must adhere to these rules, which DWeb Nodes enforce.

{
  "method": "ProtocolsConfigure",
  "protocol": "https://decentralized-social-example.org/protocol/",
  "protocolVersion": "1.0.0",
  "description": "...",
  "definition": {
    "labels": {
      "post": {
        "schema": "https://decentralized-social-example.org/schemas/post",
        "dataFormat": ["application/json"],
        "purpose": "Enables you to post social messages others can read"
      },
      "reply": {
        "schema": "https://decentralized-social-example.org/schemas/reply",
        "dataFormat": ["application/json"],
        "purpose": "Allows others to reply to your social posts"
      },
      "image": {
        "dataFormat": ["image/jpeg", "image/png", "image/gif"],
        "purpose": "Attach images to posts and replies"
      }
    },
    "records": {
      "post": {
        "records": {
          "image": {},
          "reply": {
            "recursive": true,
            "records": {
              "image": {
                "allow": {
                  "author": {
                    "of": "post.reply",
                    "to": {
                      "create": {
                        "publication": "required"
                      }
                    }
                  }
                }
              }
            },
            "allow": {
              "anyone": {
                "to": {
                  "create": {
                    "publication": "required"
                  }
                }
              }
            }
          }
        }
      }
    }
  }
}
TODO

ADD PROTOCOL DEFINITION SPEC TEXT

§ Processing Instructions

When processing a ProtocolsConfigure message, a conforming implementation MUST perform the following steps:

  1. If the message has a lastConfiguration property, ensure the referenced CID value links to a valid previous configuration for the specified protocol + version;
  2. If the message: 2a. Does not contain a protocolDefinition property, process the configuration as if the protocol + version is closed for interaction. 2b. Does contain a protocolDefinition property, perform any indexing, setup, or optimization processes required to begin enforcing it within the implementation.
  3. Store the configuration.

§ ProtocolsQuery

The ProtocolsQuery interface method allows an outside entity to query for any active protocols the owner has an active configuration for.

{
	"method": "ProtocolsQuery",
  "filter": {
    "protocol": "identity.foundation/protocols/credential-issuance",
    "versions": ["1.0.0", "2.0.0"]
  }
}

§ Permissions

The Permissions interface provides a mechanism for external entities to request access to various data and functionality provided by a Decentralized Web Node. Permissions employ a capabilities-based architecture that allows for DID-based authorization and delegation of authorized capabilities to others, if allowed by the owner of a Decentralized Web Node.

§ PermissionsRequest

PermissionsRequest messages are JSON objects that include general Message Descriptor properties and the following additional properties, which must be composed as follows:

{
  "descriptor": {
    "method": "PermissionsRequest",
    "permissionRequestId": "b6464162-84af-4aab-aff5-f1f8438dfc1e",
    "grantedBy": "did:example:alice",
    "grantedTo": "did:example:bob",
    "description": "Help you create and edit your music playlists",
    "scope": {
      "method": "CollectionsWrite",
      "schema": "https://schema.org/MusicPlaylist"
    },
    "conditions": {
      "delegation": true,
      "publication": true,
      "sharedAccess": true,
      "encryption": "optional",
      "attestation": "prohibited"
    }
  },
  "authorization": {
    "payload": "89f5hw458fhw958fq094j9jdq0943j58jfq09j49j40f5qj30jf",
    "signatures": [{
      "protected": "4d093qj5h3f9j204fq8h5398hf9j24f5q9h83402048h453q",
      "signature": "49jq984h97qh3a49j98cq5h38j09jq9853h409jjq09h5q9j4"
    }]
  }
}

§ PermissionsGrant

PermissionsGrant messages are JSON objects containing capabilities granted to parties that curtail the scope of permitted activities an invoker can perform. They are generated either in response to a PermissionsRequest message or optimistically by a user agent without an initiating PermissionsRequest. PermissionsGrant messages include general Message Descriptor properties and the following additional properties:

{
  "descriptor": {
    "method": "PermissionsGrant",
    "permissionGrantId": "f45wve-5b56v5w-5657b4e-56gqf35v",
    "permissionRequestId": "b6464162-84af-4aab-aff5-f1f8438dfc1e",
    "grantedBy": "did:example:bob",
    "grantedTo": "did:example:carol",
    "expiry": 1575606941,
    "delegatedFrom": PARENT_PERMISSION_GRANT,
    "scope": {
      "method": "CollectionsWrite",
      "schema": "https://schema.org/MusicPlaylist",
      "recordId": "f45wve-5b56v5w-5657b4e-56gqf35v"
    },
    "conditions": {
      "delegation": true,
      "publication": true,
      "sharedAccess": true,
      "encryption": "optional",
      "attestation": "prohibited"
    }
  },
  "authorization": {
    "payload": "89f5hw458fhw958fq094j9jdq0943j58jfq09j49j40f5qj30jf",
    "signatures": [{
      "protected": "4d093qj5h3f9j204fq8h5398hf9j24f5q9h83402048h453q",
      "signature": "49jq984h97qh3a49j98cq5h38j09jq9853h409jjq09h5q9j4"
    }]
  },
  "encryptionKey": { 
    "protected": ...,
    "recipients": ...,
    "ciphertext": ...,
    "iv": ...,
    "tag": ... 
  }
}
§ Granted Encryption Keys

The encryptionKey attribute of a PermissionsGrant is a [RFC7516] JSON Web Encryption (JWE) object that is composed as follows:

  1. The kid field of the JWE header MUST be a DID URL that identifies the public key type designated for encryption in the DID Document of the PermissionGrant recipient.
  2. The ciphertext field MUST be encrypted with the X25519 public key designated for encryption in the DID Document of the PermissionGrant recipient.
  3. The data encrypted in the object’s ciphertext field MUST be the JSON Web Key (JWK) object representation of a AES-256 symmetric encryption key generated by the owner of the DWeb Node that will be used to encrypt the data transacted in relation to the associated PermissionGrant.
§ Grantor PermissionsGrant Storage

After generating a PermissionsGrant the user agent (e.g. wallet app with access to authoritative keys for a given DID) MUST commit the granted permission object to the Decentralized Web Node of the DID the grant was issued from. This will ensure that the permission is present when addressed in subsequent interface method invocations.

§ Grantee PermissionsGrant Delivery

Once a user agent (e.g. wallet app with access to authoritative keys for a given DID) generates a PermissionsGrant for an entity to permit access to data and functionality, it is the responsibility of the user agent that generated the PermissionsGrant to deliver it to the entity that is the subject. To do this, the user agent MUST generate a Request that includes the PermissionsGrant and send it to the Decentralized Web Node of the subject it has been granted to, in accordance with the Resolution and Request Construction sections of this specification.

§ PermissionsRevoke

Revocation of a permission is the act of closing off any additional or invalid invocations of that permission. The Revoke interface method enables revocation of a permission via direct reference to the permission’s ID.

{ // Message
  "descriptor": { // Message Descriptor
    "method": "PermissionsRevoke",
    "permissionRevokeId": "sdfa4162-84af-4aab-aff5-f1f8438dfc1e",
    "permissionGrantId": "b6464162-84af-4aab-aff5-f1f8438dfc1e"
  }
}

§ PermissionsQuery

The PermissionQuery method exists to facilitate lookup of any retained Permissions objects that exist in a given DID’s DWeb Node instance.

{ // Message
  "descriptor": { // Message Descriptor
    "method": "PermissionsQuery",
    "grantedTo": "did:example:bob"
  }
}

§ Hooks

Many apps and services require the ability to subscribe to types and subsets of data that enters an individual’s DWeb Node to act on it, with the ability to respond to the entity that initiated the write or modification to the data. The most common mechanism known to developers that does the first half this is Web Hooks. Web Hooks are one-way pushes of data to subscribed entities, but do not account for responding to the entities that trigger their invocations.

DWeb Node Hooks aim to not only allow permissioned subscribers to be notified of new data, but also optionally respond to the entity’s request that triggers their invocation. This allows a subscribed entity to process the data and send back responses to the entity who may be waiting on results.

§ HooksWrite

HooksWrite messages are JSON objects that include general Message Descriptor properties and the following additional properties, which must be composed as follows:

Adding a hook for social media postings:

{ // Message
  "descriptor": {
    "method": "HooksWrite",
    "hookId": "234452-563658-5563-63546",
    "uri": "https://some-domain.com/dwn-hook",
    "filter": {
      "protocol": "https://example.com/protocols/social-media",
      "schema": "https://schema.org/SocialMediaPosting"
    }
  }
}

Updating a previously added hook:

{ // Message
  "descriptor": {
    "parentId": CID_OF_PREVIOUS_INSTANCE,
    "method": "HooksWrite",
    "hookId": "234452-563658-5563-63546",
    "uri": "https://a-different-domain.com/new/path",
    "filter": {
      "protocol": "https://example.com/protocols/social-media",
      "schema": "https://schema.org/SocialMediaPosting"
    }
  }
}
§ HooksWrite Ingest Instructions

If the parentId property:

§ HooksQuery

HooksQuery messages are JSON objects that include general Message Descriptor properties and the following additional properties, which must be composed as follows:

Get all active hooks Alice has written:

{ // Message
  "descriptor": {
    "method": "HooksQuery",
    "filter": {
      "writer": "did:example:alice",
      "active": true
    }
  }
}

§ HooksDelete

HooksWrite messages are JSON objects that include general Message Descriptor properties and the following additional properties, which must be composed as follows:

Deleting a hook:

{ // Message
  "descriptor": {
    "method": "HooksDelete",
    "recordId": "234452-563658-5563-63546",
    "parentId": CID_OF_HOOK_INSTANCE_TO_DELETE
  }
}
§ HooksDelete Ingest Instructions
  1. If the parentId or recordId properties are IS NOT present, discard the object and return a Message-Level Status Coding error response of 400.
  2. If the parentId property IS present and the message indicated by the CID has the same recordId property value, delete the hook message referenced by the parentId, and retain the HooksDelete message as a tombstone.

§ Sync

The Sync interface and its methods allow different Decentralized Web Nodes to communicate and sync on the state of the data they contain, including replication of messages and files.

§ Commit Strategies

Collections interface records may operate under the data modification algorithms detailed below. A record may only operate under one commit strategy at a time, as indicated via the value set on the strategy property of the current CollectionsWrite root.

Strategy Name Notes
— Default strategy, no need to add a commitStrategy property is required.
json-patch Delta-based JSON-type document patching, as defined in [spec:rfc6902]
json-merge Simple deep-merge modification strategy for JSON-type documents, as defined in [spec:rfc7386]

§ JSON Patch

TODO

Detail JSON Patch as a commit strategy option.

§ JSON Merge Patch

TODO

Detail JSON Merge Patch as a commit strategy option.

§ Configurations

While it is strongly encouraged to implement the full set of Decentralized Web Node features and Interfaces, not all devices and providers may be capable of doing so. To allow for maximum reach and proliferation in the ecosystem, the following are well-recognized configurations of Decentralized Web Node feature sets that tend to serve different purposes.

§ Open Data Publication

This Decentralized Web Node configuration is ideal for implementers who seek to expose intentionally public data via the Decentralized Web Node semantic data discovery Interfaces. This implementation is lightweight does not require the implementer to support any of the authentication, permissioning, or ingest mechanisms that other features and Interfaces do.

{
  "type": "FeatureDetection",
  "interfaces": {
    "collections": {
      "CollectionsQuery": true
    }
  }
}

§ Supported Encryption Schemes

A conforming implementation MUST be capable of encrypting and decrypting data stored in Decentralized Web Nodes using the following combinations of cryptographic schemes. Each scheme is a pair, wherein the symmetric keys are used to encrypt the data being protected, then subsequently shared with permitted recipients via encryption of the symmetric keys using the asymmetric key of each recipient.

Asymmetric Key Symmetric Key
X25519 AES-GCM
X25519 XSalsa20-Poly1305

§ Supported Encryption Formats

A conforming implementation MUST be capable of encrypting and decrypting data stored in Decentralized Web Nodes using the following combinations of cryptographic schemes. Each scheme is a pair, wherein the symmetric keys are used to encrypt the data being protected, then subsequently shared with permitted recipients via encryption of the symmetric keys using the asymmetric key of each recipient.

Label Format
jwe AES-GCM
X25519 XSalsa20-Poly1305

§ Normative References

RFC3339
Date and Time on the Internet: Timestamps. G. Klyne; C. Newman; 2002-07. Status: Proposed Standard.
RFC4122
A Universally Unique IDentifier (UUID) URN Namespace. P. Leach; M. Mealling; R. Salz; 2005-07. Status: Proposed Standard.
RFC7515
JSON Web Signature (JWS). M. Jones; J. Bradley; N. Sakimura; 2015-05. Status: Proposed Standard.
RFC7516
JSON Web Encryption (JWE). M. Jones; J. Hildebrand; 2015-05. Status: Proposed Standard.
RFC7519
JSON Web Token (JWT). M. Jones; J. Bradley; N. Sakimura; 2015-05. Status: Proposed Standard.

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