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# Trusted Digital Web (TDW) Decentralized Identifier Name System (TDWNS) DID Method Specification version 1.0.1

# Web 7.0 Ultraweb Decentralized Identifier Name System (DIDNS) DID Method Specification version 1.0.1

Web 7.0 Ultraweb DIDNS Sample Query (live):

https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_diddoc.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory/TXT/UDP/false/

## 1. Context

### Purpose

The purpose of a DID Method Specification is to define the following:

- DID Identifier Syntax and Construction

- DID Identifier Query Operators

- DID Document CRUD Abstract Interface(s)

- DID Method Platform Implementation Guidance

The Trusted Digital Web (TDW) Decentralized Identifier Name System (TDWNS) DID Method Specification (TDWNS DID Method Specification)

The Web 7.0 Ultraweb Decentralized Identifier Name System (DIDNS) DID Method Specification (Web 7.0 DIDNS DID Method Specification)

defines the end-to-end lifecycle of DID Identifiers and DID Documents for use in the Trusted Digital Web ecosystem.

defines the end-to-end lifecycle of DID Identifiers and DID Documents for use in the Web 7.0 Ultraweb ecosystem.

The Trusted Digital Web (TDW) runs on top of Web 7.0.

Web 7.0 is a secure, message-based, decentralized operating system that underpins a unified software and hardware ecosystem for building resilient, trusted, decentralized systems using decentralized identifiers, DIDComm agents, and verifiable credentials.

The Web 7.0 Foundation, a federally-incorporated Canadian non-profit organization, is chartered to support, promote, protect, and curate the Web 7.0 ecosystem: operating system software, standards, and specifications; as well as other software and technology projects. The Web 7.0 project is an offspring of the Trusted Digital Web (TDW) project (http://github.com/mwherman2000/TrustedDigitalWeb).

This specification defines the following:

- TDWNS Identifier Syntax and Construction

- DIDNS Identifier Syntax and Construction

- TDWNS Identifier DID Document CRUD Abstract Interface

- DIDNS Identifier DID Document CRUD Abstract Interface

This specification also provides Platform Implementation Guidance to assist Implementors in creating safe and secure TDW apps, agents, services and platforms that are compliant with the TDWNS DID Method Specification.

This specification also provides Platform Implementation Guidance to assist Implementors in creating safe and secure Web 7.0 apps, agents, services and platforms that are compliant with the DIDNS DID Method Specification.

### Out-of-Scope

The following topics are out-of-scope:

- Descriptions of any implementation-specific design, implementation, or deployment details for any particular software platform that might support the TDWNS DID Method Namespace.

- Descriptions of any implementation-specific design, implementation, or deployment details for any particular software platform that might support the DIDNS DID Method Namespace.

### Intended Audience

The primary audience for this DID Method Specification is Implementors of TDW apps, DIDComm agents, and services; including but not limited to:

The primary audience for this DID Method Specification is Implementors of Web 7.0 apps, DIDComm agents, and services; including but not limited to:

software architects, data modelers, application developers, services developers, testers, operators, and user experience (UX) specialists.

In addition, other people involved in a broad range of standards efforts related to decentralized identity,

verifiable credentials, and secure storage may also be interested in reading this specification.

### Terminology

- The term TDWNS Identifier is synonymous with the term TDWNS Decentralized Identifier.

- The term DIDNS Identifier is synonymous with the term DIDNS Decentralized Identifier.

- The term TDWNS Identifier DID Document is synonymous with the term TDWNS Decentralized Identifier Document.

- The term DIDNS Identifier DID Document is synonymous with the term DIDNS Decentralized Identifier Document.

- The term TDWNS DID Method Specification is synonymous with the term TDWNS Decentralized Identifier Name System (TDWNS) DID Method Specification..

- The term DIDNS DID Method Specification is synonymous with the term DIDNS Decentralized Identifier Name System (DIDNS) DID Method Specification..

- A compliant TDWNS runtime library is a software library that, in part, implements the TDWNS Identifier DID Document CRUD Abstract Interface in a way that complies with the TDWNS DID Method Specification.

- A compliant DIDNS runtime library is a software library that, in part, implements the DIDNS Identifier DID Document CRUD Abstract Interface in a way that complies with the DIDNS DID Method Specification.

### Conformance

This specification conforms to the requirements specified in the

Decentralized Identifiers (DIDs) v1.0 W3C Proposed Recommendation[2]

published by the W3C Decentralized Identifier Working Group.

### Variations

Three (3) variations of the did:ns DID method are currently supported.

- TDW DID Name System over DNS (TDWNS/DNS) (reference implementation)

- DID Name System over DNS (DIDNS/DNS) (reference implementation)

- TDW DID Name System over Microsoft Active Directory/Azure Directory Services (TDWNS/AD)

- DID Name System over Microsoft Active Directory/Azure Directory Services (DIDNS/AD)

- TDW DID Name System over X.500/LDAP (TDWNS/LDAP)

- DID Name System over X.500/LDAP (DIDNS/LDAP)

This specification describes the design of the DIDNS/DNS reference implementation.

### Authoritative Source Text

The authoriative source text for this specification can be found here: https://github.com/Web7Foundation/Specifications/blob/main/methods/did-tdw-1-0-1.md.

The authoriative source text for this specification can be found here: https://github.com/Web7Foundation/Specifications/blob/main/methods/did-ns-1-0-1.md.

### Example 1. TDWNS Identifier Example

### Example 1. DIDNS Identifier Example

```

did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914

did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914

did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_diddoc

did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_diddoc

did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_didid

did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_didid

did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_didkey

did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_didkey

```

### Example 2. Anonymous TDWNS Identifier Example

### Example 2. Anonymous DIDNS Identifier Example

```

did:tdw:fe042e80-e963-4a35-9734-7d1eaeb1b06e

did:ns:fe042e80-e963-4a35-9734-7d1eaeb1b06e

did:tdw:fe042e80-e963-4a35-9734-7d1eaeb1b06e:_diddoc

did:ns:fe042e80-e963-4a35-9734-7d1eaeb1b06e:_diddoc

did:tdw:fe042e80-e963-4a35-9734-7d1eaeb1b06e:_didid

did:ns:fe042e80-e963-4a35-9734-7d1eaeb1b06e:_didid

did:tdw:fe042e80-e963-4a35-9734-7d1eaeb1b06e:_didkey

did:ns:fe042e80-e963-4a35-9734-7d1eaeb1b06e:_didkey

```

## 2. TDW Decentralized Identifier Name System (TDWNS) Name

## 2. Decentralized Identifier Name System (DIDNS) Name

The name string that **MUST** be used to label a TDW Decentralized Identifier Name System (TDWNS) Identifier is: ```tdw```.

The name string that **MUST** be used to label a Decentralized Identifier Name System (DIDNS) Identifier is: ```ns```.

A TDWNS Identifier that uses this method **MUST** begin with the following prefix: ```did:tdw```.

A DIDNS Identifier that uses this method **MUST** begin with the following prefix: ```did:ns```.

Per the DID Decentralized Identifier specification[2], the value of this string **MUST** be in lowercase.

## 3. TDWNS Identifier Format

## 3. DIDNS Identifier Format

Compliant TDWNS Identifiers **MUST** use the following format:

Compliant DIDNS Identifiers **MUST** use the following format:

```

NSPREFIX = "did"

NSID = "tdw"

NSID = "ns"

did-tdw-did = NSPREFIX : NSID label

did-ns-did = NSPREFIX : NSID label

label = *(label-separator label-string)

label-separator = ":"

label-string = 1*label-chars | label-hidden-prefix 1*label-chars

label_chars = ALPHA / DIGIT / "-" / pct-encoded

pct-encoded = "%" HEXDIG HEXDIG

label-hidden-prefix = "_"

```

### 3.1 TDWNS Identifier Samples

### 3.1 DIDNS Identifier Samples

| Sample | Notation |

| :----: | -------- |

| 1 | ```did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914``` |

| 1 | ```did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914``` |

| 2 | ```did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_diddoc``` |

| 2 | ```did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_diddoc``` |

| 3 (not live) | [```did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_diddoc```](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_diddoc.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.did-tdw.directory/ANY/UDP/false/) [(click)](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_diddoc.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.did-tdw.directory/ANY/UDP/false/) |

| 3 (live) | [```did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_diddoc```](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_diddoc.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory/TXT/UDP/false/) [(click)](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_diddoc.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory/ANY/UDP/false/) |

| 4 (not live) | [```did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_didid```](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_didid.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.did-tdw.directory/ANY/UDP/false/) [(click)](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_didid.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.did-tdw.directory/ANY/UDP/false/) |

| 4 (live) | [```did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_didid```](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_didid.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory/TXT/UDP/false/) [(click)](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_didid.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory/TXT/UDP/false/) |

### 3.2 TDWNS Identifier Transformation

### 3.2 DIDNS Identifier Transformation

| Transform Steps | Example |

| ------------------ | ------- |

| 1. TDWNS Notation | ```did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914``` |

| 1. DIDNS Notation | ```did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914``` |

| 2. URN Notation | ```urn:did-tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914``` |

| 2. URN Notation | ```urn:didns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914``` |

| 3. URL Notation | ```0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.did-tdw.directory``` |

| 3. URL Notation | ```0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory``` |

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# Trusted Digital Web (TDW) Decentralized Identifier Name System (TDWNS) DID Method Specification version 1.0.1

## 1. Context

### Purpose

The purpose of a DID Method Specification is to define the following:
- DID Identifier Syntax and Construction
- DID Identifier Query Operators
- DID Document CRUD Abstract Interface(s)
- DID Method Platform Implementation Guidance

The Trusted Digital Web (TDW) Decentralized Identifier Name System (TDWNS) DID Method Specification (TDWNS DID Method Specification) 
defines the end-to-end lifecycle of DID Identifiers and DID Documents for use in the Trusted Digital Web ecosystem.

The Trusted Digital Web (TDW) runs on top of Web 7.0.

This specification defines the following:
- TDWNS Identifier Syntax and Construction
- TDWNS Identifier DID Document CRUD Abstract Interface

### Out-of-Scope

The following topics are out-of-scope:
- Descriptions of any implementation-specific design, implementation, or deployment details for any particular software platform that might support the TDWNS DID Method Namespace.

### Intended Audience

The primary audience for this DID Method Specification is Implementors of TDW apps, DIDComm agents, and services; including but not limited to: 
software architects, data modelers, application developers, services developers, testers, operators, and user experience (UX) specialists. 
In addition, other people involved in a broad range of standards efforts related to decentralized identity,
verifiable credentials, and secure storage may also be interested in reading this specification.

### Terminology

- The term TDWNS Identifier is synonymous with the term TDWNS Decentralized Identifier. 
- The term TDWNS Identifier DID Document is synonymous with the term TDWNS Decentralized Identifier Document.
- The term TDWNS DID Method Specification is synonymous with the term TDWNS Decentralized Identifier Name System (TDWNS) DID Method Specification..
- A compliant TDWNS runtime library is a software library that, in part, implements the TDWNS Identifier DID Document CRUD Abstract Interface in a way that complies with the TDWNS DID Method Specification.

### Conformance

This specification conforms to the requirements specified in the 
Decentralized Identifiers (DIDs) v1.0 W3C Proposed Recommendation[2] 
published by the W3C Decentralized Identifier Working Group.

### Variations

Three (3) variations of the did:ns DID method are currently supported.

- TDW DID Name System over DNS (TDWNS/DNS) (reference implementation)
- TDW DID Name System over Microsoft Active Directory/Azure Directory Services (TDWNS/AD)
- TDW DID Name System over X.500/LDAP (TDWNS/LDAP)

This specification describes the design of the DIDNS/DNS reference implementation.

### Authoritative Source Text

The authoriative source text for this specification can be found here: https://github.com/Web7Foundation/Specifications/blob/main/methods/did-tdw-1-0-1.md.

### Example 1. TDWNS Identifier Example
```
did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914
did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_diddoc
did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_didid
did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_didkey
```

### Example 2. Anonymous TDWNS Identifier Example
```
did:tdw:fe042e80-e963-4a35-9734-7d1eaeb1b06e
did:tdw:fe042e80-e963-4a35-9734-7d1eaeb1b06e:_diddoc
did:tdw:fe042e80-e963-4a35-9734-7d1eaeb1b06e:_didid
did:tdw:fe042e80-e963-4a35-9734-7d1eaeb1b06e:_didkey
```

## 2. TDW Decentralized Identifier Name System (TDWNS) Name

The name string that **MUST** be used to label a TDW Decentralized Identifier Name System (TDWNS) Identifier is: ```tdw```.

A TDWNS Identifier that uses this method **MUST** begin with the following prefix: ```did:tdw```. 
Per the DID Decentralized Identifier specification[2], the value of this string **MUST** be in lowercase.

## 3. TDWNS Identifier Format

Compliant TDWNS Identifiers **MUST** use the following format:
```
NSPREFIX                   = "did"
NSID                       = "tdw"
did-tdw-did                = NSPREFIX : NSID label
label                      = *(label-separator label-string)
label-separator            = ":"
label-string               = 1*label-chars | label-hidden-prefix 1*label-chars
label_chars                = ALPHA / DIGIT / "-" / pct-encoded
pct-encoded                = "%" HEXDIG HEXDIG
label-hidden-prefix        = "_"
```

### 3.1 TDWNS Identifier Samples

| Sample  | Notation |
| :----:  | -------- |
| 1 | ```did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914``` |
| 2 |   ```did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_diddoc``` |
| 3 (not live) | [```did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_diddoc```](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_diddoc.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.did-tdw.directory/ANY/UDP/false/) [(click)](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_diddoc.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.did-tdw.directory/ANY/UDP/false/) |
| 4 (not live) | [```did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_didid```](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_didid.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.did-tdw.directory/ANY/UDP/false/) [(click)](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_didid.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.did-tdw.directory/ANY/UDP/false/) |

### 3.2 TDWNS Identifier Transformation

| Transform Steps    | Example |
| ------------------ | ------- |
| 1. TDWNS Notation  | ```did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914``` |
| 2. URN Notation    | ```urn:did-tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914``` |
| 3. URL Notation    | ```0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.did-tdw.directory``` |

### 3.3 TDWNS Identifier DID Document CRUD Abstract Interface

This DID Method does not define or support any query operators.

## 4. CRUD Abstract Interface
 
A TDWNS Identifier runtime library implements CRUD interfaces for controlling the lifecycle of a TDWNS Identifier and its associated DID Document that are compliant with this specification.
 
### 4.1 Create (Register)

To create a TDWNS Identifier, a program invokes the `RegIdWithPublicKey` function from a compliant TDWNS Identifier runtime library. 
The interface to register a TDWNS Identifier and its associated public key is defined as follows:
```csharp
public bool RegIdWIthPublicKey(string didobjectid, byte[] publicKey); 
```
The calling program must include two parameters: the string value of the new TDWNS Identifier to be registered and 
a cryptographic public key to act as the first management key. 
This function will return `True` if the TDWNS Identifier had not been registered previously.

### 4.2 Read (Resolve)

TDWNS Identifier's associated DID Document can be looked up by invoking the `GetDIDDocument` function from a compliant  Identifier runtime library. 
To make sure the result returned by invoking the `GetDIDDocument` function is trustworthy, the client could ask a sufficient number of nodes 
and compare each node's return value.

The interface for resolving a TDWNS Identifier and return its associated DID Document is defined as follows:
```csharp
public DIDDocument GetDIDDocument(string didobjectid);
```
A DIDDocument is a JSON object which contains the `verificationMethod`, `authentication` elements of the associated DID Document.
Every public key in the array of `verificationMethod` can be used to authenticate the TDWNS Identifier Controller.

Note: The list of supported public key signature schemes is listed in [Appendix A](#appendix-a-public-key-algorithm).

### Example 3. TDWNS Identifier DID Document

```json
{
    "id": "did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914",
    "verificationMethod": [
        {
            "id": "did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914#key-1",
            "type": "Ed25519VerificationKey2020",
            "controller": "did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914",
            "publicKeyMultibase": "zEY59y7px76e2yv5FMj9fYcjDsqk8yus6isWtkF69ZrHY"
        }
    ],
    "authentication": ["did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914#key-1"],
    "assertionMethod": ["did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914#key-1"],
    "service": [{
        "id":"#default",
        "type": "default", 
        "serviceEndpoint": "https://agents.example.com/agent0"
    },
    ]
}
```

### 4.3 Update (Replace)

To update the DID Document associated with a TDWNS Identifier, two functions need to be invoked, 
```csharp
public bool AddKey(string didobjectid, byte[] newPublicKey, byte[] sender);
```
```csharp
public bool RemoveKey(string didobjectid, byte[] oldPublicKey, byte[] sender);
```
Note that `sender` param must be a currently-in-use public key of this TDWNS Identifier.
If a public key is removed, then it **cannot** be added again.

### 4.4 Deactivate (Revoke)

To delete or deactivate a TDWNS Identifier, it suffices to remove all public keys from its associated 
DID Document. In this case, there is no public key that can be used to authenticate the TDWNS Identifier Controller.

More importantly, deletion of a TDWNS Identifier DID Document means that the associated TDWNS Identifier cannot be reactivated again.

## 5. Implementation Guidance

The content is this section is non-normative.

Caveat: The applicablility of the individual guidance referenced below to a particular application domain needs to be assessed on a case-by-case basis.

### Example 3. TDWNS Identifier DNS Query Example

| DNS Operation | Example |
| ------------- | ------- |
| DNS Query | ```_diddoc.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.did-tdw.directory type=ANY``` |
| DNS Response | ```_diddoc TXT "{ \"id\" : \"did:tdw:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914\" }"``` |
|  | ```_diddoc TXT "{ \"service\" : [ { \"id\" : \"#agent0\" }, { \"type\": \"default\" }, { \"serviceEndpoint\": \"https://agents.example.com/agent0\" } ] }"``` |
|  | ```_diddoc TXT "{ \"service\" : [ { \"id\" : \"#agent1\" }, { \"type\": \"default\" }, { \"serviceEndpoint\": \"https://agents.example.com/agent1\" } ] }"``` |

![Example 3. TDWNS Identifier DNS Example](images/did-ns-dns-example-1-0-1.png)

![Example 3. TDWNS Identifier DNS Example](images/did-ns-dns-example2-1-0-1.png)

### Security Considerations

There are no security considerations that are specific to this DID Method Specification. Security considersations and requirements are the responsiblity of the particular platform Implementor - taking into consideration the types of Business Documents, Business Processes, DIDComm agents, and Application Objects processed by that platform.

Implementers need to be aware of the security and performance implications of the underlying tools and technologies 
used to develop DIDComm agents, services, and libraries that, in turn, leverage the TDWNS Identifier Method Specification; as one example, whether the underlying VDR is configured to support concensus by PoA, PoS, or PoW.

Further, Implementers are strongly encouraged to review the Security Considerations section of the DID Implementation Guide: https://w3c.github.io/did-imp-guide/#security-considerations.

In addition, consult the Security Considerations section of the Decentralized Identifiers (DIDs) (DID-CORE) specification: https://www.w3.org/TR/did-core/#security-considerations.

Lastly, the following list of best-in-class DID Method Specifications should also be consulted:

- `did:keri`: https://identity.foundation/keri/did_methods/#security-considerations
- `did:key`: https://w3c-ccg.github.io/did-method-key/#security-and-privacy-considerations
- `did:peer`: https://identity.foundation/peer-did-method-spec/index.html#security-considerations
- `did:tezos`: https://did-tezos.spruceid.com/#security-considerations
- `did:trustblock`: https://github.com/trustbloc/trustbloc-did-method/blob/main/docs/spec/trustbloc-did-method.md#security-considerations
- `did:web`: https://w3c-ccg.github.io/did-method-web/#security-and-privacy-considerations

### Privacy Considerations

There are no privacy considerations that are specific to this DID Method Specification. Privacy considersations and requirements are the responsiblity of the particular platform Implementor - taking into consideration the types of Business Documents, Business Processes, DIDComm agents, and Application Objects processed by that platform.

The syntax and construction of a TDWNS Identifier and its associated DID Document helps to ensure that no Personally Identifiable Information (PII) or other personal data is exposed by these constructs.

Implementers need to be aware of the privacy implications of the underlying tools and technologies 
used to develop DIDComm agents, services, and libraries that in turn, leverage the TDWNS Identifier Method Specification.

Further, Implementers are strongly encouraged to review the Privacy Considerations section of the DID Implementation Guide: https://w3c.github.io/did-imp-guide/#privacy-considerations.

In addition, consult the Privacy Considerations section of the Decentralized Identifiers (DIDs) (DID-CORE) specification: https://www.w3.org/TR/did-core/#privacy-considerations.

Lastly, the following list of best-in-class DID Method Specifications should also be consulted:

- `did:keri`: https://identity.foundation/keri/did_methods/#privacy-considerations
- `did:key`: https://w3c-ccg.github.io/did-method-key/#security-and-privacy-considerations
- `did:peer`: https://identity.foundation/peer-did-method-spec/index.html#privacy-considerations
- `did:tezos`: https://did-tezos.spruceid.com/#privacy-considerations
- `did:trustblock`: https://github.com/trustbloc/trustbloc-did-method/blob/main/docs/spec/trustbloc-did-method.md#privacy-considerations
- `did:web`: https://w3c-ccg.github.io/did-method-web/#security-and-privacy-considerations

## 6. Reference Implementations

A version of the code for the Decentralized Identifier Name System (TDWNS) reference implementation can be found in the following GitHub project: https://github.com/Web7Foundation/DnsServer. 
This project is the definitive reference implementation of the Decentralized Identifier Name System (TDWNS) and contains compliant reference implementations of 
TDW apps, DIDComm agents, and services.

## 7. Acknowledgments

The project is gratefully to all the members of the 
DID-CORE, Verifiable Credentials, and Confidential Storage working groups (hosted by W3C and DIF) for their years of support.

## Appendix A. Public Key Algorithm

There are three public key algorithms supported in this document. 
1. ECDSA
2. SM2
3. EdDSA

### ECDSA

The curves that can be used are:

- secp224r1 -- same as nistp224
- secp256r1 -- same as nistp256 
- secp384r1 -- same as nistp384 
- secp521r1 -- same as nistp521

More curves may be supported in future versions of this Method.

### SM2

There is only one curve that can be used, namely, `sm2p256v1` as defined in [SM2 Digital Signature Algorithm](https://tools.ietf.org/html/draft-shen-sm2-ecdsa-02#appendix-D).

### EdDSA

There is only one curve that can be used, namely, `ed25519`.

## References

References and historical record of related publications.

[0] TDW DIDComm Agent Architecture Reference Model (DIDComm-ARM) 0.40 (December 18, 2022), https://hyperonomy.com/2022/12/18/web-7-0-didcomm-agent-architecture-reference-model-didcomm-arm-0-40-december-18-2022/.

[1] Trusted Digital Web: Whitepaper, https://hyperonomy.com/2019/11/06/trusted-digital-web-whitepaper/.

[2] Decentralized Identifiers (DIDs) v1.0 W3C Proposed Recommendation, https://w3c-ccg.github.io/did-spec/.

[3] IETF Internet draft, SM2 Digital Signature Algorithm, https://tools.ietf.org/html/draft-shen-sm2-ecdsa-02.

[4] Tokenize Every Little Thing (ELT), https://hyperonomy.com/2018/01/24/tokenization-of-every-little-thing-elt/.

[5] The Verifiable Economy Architecture Reference Model (VE-ARM): Fully Decentralized Object (FDO) Model, https://hyperonomy.com/2021/04/26/the-verifiable-economy-architecture-reference-model-ve-arm-fdo/.

[6] The Verifiable Economy: Fully Decentralized Object (FDO) Example: Bob’s UDID Document, https://hyperonomy.com/2021/06/15/the-verifiable-economy-fully-decentralized-object-fdo-example-bobs-udid-document/.

[7] Trusted Digital Web: 8-Layer Architecture Reference Model (TDW-ARM), https://hyperonomy.com/2021/06/28/trusted-digital-web-8-layer-architecture-reference-model-tdw-arm/.

[8] DIF SDS/CS WG: CS Refactoring Proposal 0.2 – March 24, 2021, https://hyperonomy.com/2021/03/28/cs-refactoring-proposal/.

[9] Trusted Digital Web: Trusted Content Storage (TCS) Whitepapers, https://hyperonomy.com/2021/03/17/trusted-digital-web-trusted-content-storage-whitepapers/.

[10] Fully Decentralized Twitter (Dewitter) App Scenario: Platform Requirements (presentation to DIF SDS/CS WG – March 18, 2021), https://hyperonomy.com/2021/03/18/fully-decentralized-twitter-dewitter-app-scenario-platform-requirements-presentation/.

[11] TDW Decentralized Glossary Management and Collaboration Platform (TDW Glossary): Digital Identity Neighborhood, https://hyperonomy.com/2021/03/15/tdw-glossary-management-and-collaboration-platform-tdw-gmcp-digital-identity-neighborhood/.

[12] TDW Hub Architecture Reference Model (HUB-ARM) – Version 0.104, https://hyperonomy.com/2021/03/11/tdw-hub-architecture-reference-model-hub-arm/.

[13] Technology Adoption Models: A Comprehensive Guide, https://hyperonomy.com/2019/10/16/technology-adoption-models/.

[14] Is the Social Evolution Model Harmful?, https://hyperonomy.com/2021/02/10/is-the-social-evolution-model-harmful/.

[15] Secure Data Storage Working Group (sds-wg) Confidential Storage (CS): Functional Architecture Reference Models (CS-FARMs) 0.36 (whitepaper placeholder): Sample Diagrams, https://hyperonomy.com/2021/02/10/secure-data-storage-working-group-sds-wg-confidential-storage-cs-functional-architecture-reference-models-cs-farms/.

[16] Trusted Digital Assistant: Conceptual Architecture, https://hyperonomy.com/2021/02/03/trusted-digital-assistant-conceptual-architecture/.

[17] What is SSI?, https://hyperonomy.com/2021/02/01/ssi-unconscious-contractions/.

[18] Trusted Digital Web: First Trusted Web Page Delivered Today – Dec. 3, 2019, https://hyperonomy.com/2019/12/03/trusted-digital-web-first-trusted-web-page-delivered-today-dec-3-2019/.

[19] Trusted Digital Web: Trust Levels for Universal DIDs, https://hyperonomy.com/2019/11/21/trusted-digital-web-levels-of-universal-trust/.

[20] Business Choreography and the #TrustedDigitalWeb, https://hyperonomy.com/2019/04/16/business-choreography-and-the-trusteddigitalweb/.

[21] Social Evolution and Technology Adoption, https://hyperonomy.com/2019/04/08/social-evolution-and-technology-adoption/.

[22] The #OpenToInnovation Principle: Internet protocols and standards not only need to be open, but more importantly, open to innovation, https://hyperonomy.com/2019/03/12/internet-protocols-and-standards-not-only-need-to-be-open-but-more-importantly-open-to-innovation/.

[23] Giving Grammars Written with ABNF Notation the Respect They Deserve, https://hyperonomy.com/2019/03/11/giving-grammars-written-with-abnf-notation-the-respect-they-deserve/.

[24] SerentityData: Variable-byte, Statistically-based Entity Serialization & Field Encoding, https://hyperonomy.com/2019/02/06/serentitydata-variable-byte-statistically-based-entity-serialization-field-encoding/.

[25] #iDIDit: [OLD] An Architecture-driven Taxonomy for SSI DIDComm agents v0.5, https://hyperonomy.com/2019/02/01/architecture-driven-taxonomy-for-ssi-DIDComm agents/.

[26] #iDIDit: What is a DID?, https://hyperonomy.com/2019/01/24/what-is-a-did/.

[27] #iDIDit: [OLD] Hyperledger Indy/Sovrin Comprehensive Architecture Reference Model (INDY ARM) v0.21, https://hyperonomy.com/2019/01/13/hyperledger-indy-sovrin-comprehensive-architecture-reference-model-arm/.

[28] #iDIDit: [OLD] End-to-end Path from a id (DID) to a Real-Life Something v0.3, https://hyperonomy.com/2019/01/04/the-path-from-a-id-did-to-a-real-life-something/.

[29] #iDIDit: What’s more important? …the name of something or the something?, https://hyperonomy.com/2019/01/02/whats-more-important-the-name-of-something-or-the-something/.

[30] DNS (Domain Name Service): A Detailed, High-level Overview, https://hyperonomy.com/2019/01/02/dns-domain-name-service-a-detailed-high-level-overview/.

[31] #iDIDit: [OLD] Decentralized Identifiers (DIDs) Architecture Reference Model (ARM), https://hyperonomy.com/2018/12/21/decentralized-identifiers-dids-architecture-reference-model-arm/.

[32] Refactoring UBL 2.2 business documents for enacting business processes on the blockchain [WIP], https://hyperonomy.com/2018/12/06/refactoring-ubl-2-2-business-documents-for-enacting-business-processes-on-the-blockchain-wip/.

[33] Ethereum .NET Development Examples using the Nethereum Integration Libraries, https://hyperonomy.com/2017/12/19/ethereum-net-examples-using-the-nethereum-libraries/.

[34] #Graphitization of the Amazon Leadership Principles (introducing Personal Leadership Principle Maps) – Iteration 1, https://hyperonomy.com/2017/05/08/amazons-principles/.

[35] Stratis Academy. https://academy.stratisplatform.com/Architecture%20Reference/architecture-reference-introduction.html.

[36] Key Event Receipt Infrastructure - the spec and implementation of the KERI protocol, https://identity.foundation/keri/.

[37] KEY EVENT RECEIPT INFRASTRUCTURE (KERI) DESIGN (whitepaper), https://github.com/decentralized-identity/keri/blob/master/kids/KERI_WP.pdf.

[38] DIF, KERI Project, https://github.com/decentralized-identity/keri.

[39] W3C, Decentralized Identifiers (DIDs) (DID-CORE) specification: https://www.w3.org/TR/did-core/.

[40] OMG, Business Process Model and Notation (BPMN), https://www.omg.org/spec/BPMN/2.0/PDF.

[41] OASIS, Universal Business Language Version 2.2 (UBL), http://docs.oasis-open.org/ubl/UBL-2.2.html.

[42] Trinity Graph Engine open source project, https://www.graphengine.io/.

[43] Trinity Graph Engine GitHub repository, https://github.com/Microsoft/GraphEngine.

[44] Object Linking and Embedding (OLE), https://en.wikipedia.org/wiki/Object_Linking_and_Embedding.

[45] [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.

[46] [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <http://www.rfc-editor.org/info/rfc3986>.

[47] [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,
              <http://www.rfc-editor.org/info/rfc5234>.

[48] [RFC1034]  P. Mockapetris, "Domain Names - Concepts and Facilities", RFC 1034,
              DOI 10.17487/RFC1034, November 1987,
              <http://www.rfc-editor.org/info/rfc1034>.

[49] [RFC1035]  Peter Saint-Andre and John C. Klensin, "Uniform Resource Names (URNs)", RFC 8141,
              DOI 10.17487/RFC8141, April 2017,
              <http://www.rfc-editor.org/info/rfc8141>.

## Copyright

Copyright &copy; 2024 Michael Herman (Alberta, Canada) – Creative Commons Attribution-ShareAlike 4.0 International Public License
https://creativecommons.org/licenses/by-sa/4.0/legalcode

## Epilogue

>An Internet specification is like steam (or a horse) - if you don't harness it and put it to work, its value is marginalized.

- Why is Knowledge like Steam?, https://www.linkedin.com/pulse/why-knowledge-like-steam-michael-herman-toronto-/.

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# Web 7.0 Ultraweb Decentralized Identifier Name System (DIDNS) DID Method Specification version 1.0.1

Web 7.0 Ultraweb DIDNS Sample Query (live):

https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_diddoc.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory/TXT/UDP/false/

## 1. Context

### Purpose

The Web 7.0 Ultraweb Decentralized Identifier Name System (DIDNS) DID Method Specification (Web 7.0 DIDNS DID Method Specification) 
defines the end-to-end lifecycle of DID Identifiers and DID Documents for use in the Web 7.0 Ultraweb ecosystem.

This specification defines the following:
- DIDNS Identifier Syntax and Construction
- DIDNS Identifier DID Document CRUD Abstract Interface

### Out-of-Scope

### Intended Audience

The primary audience for this DID Method Specification is Implementors of Web 7.0 apps, DIDComm agents, and services; including but not limited to: 
software architects, data modelers, application developers, services developers, testers, operators, and user experience (UX) specialists. 
In addition, other people involved in a broad range of standards efforts related to decentralized identity,
verifiable credentials, and secure storage may also be interested in reading this specification.

### Terminology

- The term DIDNS Identifier is synonymous with the term DIDNS Decentralized Identifier. 
- The term DIDNS Identifier DID Document is synonymous with the term DIDNS Decentralized Identifier Document.
- The term DIDNS DID Method Specification is synonymous with the term DIDNS Decentralized Identifier Name System (DIDNS) DID Method Specification..
- A compliant DIDNS runtime library is a software library that, in part, implements the DIDNS Identifier DID Document CRUD Abstract Interface in a way that complies with the DIDNS DID Method Specification.

### Conformance

This specification conforms to the requirements specified in the 
Decentralized Identifiers (DIDs) v1.0 W3C Proposed Recommendation[2] 
published by the W3C Decentralized Identifier Working Group.

### Variations

Three (3) variations of the did:ns DID method are currently supported.

- DID Name System over DNS (DIDNS/DNS) (reference implementation)
- DID Name System over Microsoft Active Directory/Azure Directory Services (DIDNS/AD)
- DID Name System over X.500/LDAP (DIDNS/LDAP)

This specification describes the design of the DIDNS/DNS reference implementation.

### Authoritative Source Text

The authoriative source text for this specification can be found here: https://github.com/Web7Foundation/Specifications/blob/main/methods/did-ns-1-0-1.md.

### Example 1. DIDNS Identifier Example
```
did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914
did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_diddoc
did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_didid
did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_didkey
```

### Example 2. Anonymous DIDNS Identifier Example
```
did:ns:fe042e80-e963-4a35-9734-7d1eaeb1b06e
did:ns:fe042e80-e963-4a35-9734-7d1eaeb1b06e:_diddoc
did:ns:fe042e80-e963-4a35-9734-7d1eaeb1b06e:_didid
did:ns:fe042e80-e963-4a35-9734-7d1eaeb1b06e:_didkey
```

## 2. Decentralized Identifier Name System (DIDNS) Name

The name string that **MUST** be used to label a Decentralized Identifier Name System (DIDNS) Identifier is: ```ns```.

A DIDNS Identifier that uses this method **MUST** begin with the following prefix: ```did:ns```. 
Per the DID Decentralized Identifier specification[2], the value of this string **MUST** be in lowercase.

## 3. DIDNS Identifier Format

Compliant DIDNS Identifiers **MUST** use the following format:
```
NSPREFIX                   = "did"
NSID                       = "ns"
did-ns-did                 = NSPREFIX : NSID label
label                      = *(label-separator label-string)
label-separator            = ":"
label-string               = 1*label-chars | label-hidden-prefix 1*label-chars
label_chars                = ALPHA / DIGIT / "-" / pct-encoded
pct-encoded                = "%" HEXDIG HEXDIG
label-hidden-prefix        = "_"
```

### 3.1 DIDNS Identifier Samples

| Sample  | Notation |
| :----:  | -------- |
| 1 | ```did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914``` |
| 2 |   ```did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_diddoc``` |
| 3 (live) | [```did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_diddoc```](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_diddoc.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory/TXT/UDP/false/) [(click)](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_diddoc.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory/ANY/UDP/false/) |
| 4 (live) | [```did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914:_didid```](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_didid.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory/TXT/UDP/false/) [(click)](https://dnsclient.net/#Google%20%7B8.8.8.8%7D/_didid.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory/TXT/UDP/false/) |

### 3.2 DIDNS Identifier Transformation

| Transform Steps    | Example |
| ------------------ | ------- |
| 1. DIDNS Notation  | ```did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914``` |
| 2. URN Notation    | ```urn:didns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914``` |
| 3. URL Notation    | ```0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory``` |

### 3.3 DIDNS Identifier DID Document CRUD Abstract Interface

This DID Method does not define or support any query operators.

## 4. CRUD Abstract Interface
 
A DIDNS Identifier runtime library implements CRUD interfaces for controlling the lifecycle of a DIDNS Identifier and its associated DID Document that are compliant with this specification.
 
### 4.1 Create (Register)

To create a DIDNS Identifier, a program invokes the `RegIdWithPublicKey` function from a compliant DIDNS Identifier runtime library. 
The interface to register a DIDNS Identifier and its associated public key is defined as follows:
```csharp
public bool RegIdWIthPublicKey(string didobjectid, byte[] publicKey); 
```
The calling program must include two parameters: the string value of the new DIDNS Identifier to be registered and 
a cryptographic public key to act as the first management key. 
This function will return `True` if the DIDNS Identifier had not been registered previously.

### 4.2 Read (Resolve)

DIDNS Identifier's associated DID Document can be looked up by invoking the `GetDIDDocument` function from a compliant  Identifier runtime library. 
To make sure the result returned by invoking the `GetDIDDocument` function is trustworthy, the client could ask a sufficient number of nodes 
and compare each node's return value.

The interface for resolving a DIDNS Identifier and return its associated DID Document is defined as follows:
```csharp
public DIDDocument GetDIDDocument(string didobjectid);
```
A DIDDocument is a JSON object which contains the `verificationMethod`, `authentication` elements of the associated DID Document.
Every public key in the array of `verificationMethod` can be used to authenticate the DIDNS Identifier Controller.

Note: The list of supported public key signature schemes is listed in [Appendix A](#appendix-a-public-key-algorithm).

### Example 3. DIDNS Identifier DID Document

```json
{
    "id": "did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914",
    "verificationMethod": [
        {
            "id": "did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914#key-1",
            "type": "Ed25519VerificationKey2020",
            "controller": "did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914",
            "publicKeyMultibase": "zEY59y7px76e2yv5FMj9fYcjDsqk8yus6isWtkF69ZrHY"
        }
    ],
    "authentication": ["did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914#key-1"],
    "assertionMethod": ["did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914#key-1"],
    "service": [{
        "id":"#default",
        "type": "default", 
        "serviceEndpoint": "https://agents.example.com/agent0"
    },
    ]
}
```

### 4.3 Update (Replace)

To update the DID Document associated with a DIDNS Identifier, two functions need to be invoked, 
```csharp
public bool AddKey(string didobjectid, byte[] newPublicKey, byte[] sender);
```
```csharp
public bool RemoveKey(string didobjectid, byte[] oldPublicKey, byte[] sender);
```
Note that `sender` param must be a currently-in-use public key of this DIDNS Identifier.
If a public key is removed, then it **cannot** be added again.

### 4.4 Deactivate (Revoke)

To delete or deactivate a DIDNS Identifier, it suffices to remove all public keys from its associated 
DID Document. In this case, there is no public key that can be used to authenticate the DIDNS Identifier Controller.

More importantly, deletion of a DIDNS Identifier DID Document means that the associated DIDNS Identifier cannot be reactivated again.

## 5. Implementation Guidance

The content is this section is non-normative.

Caveat: The applicablility of the individual guidance referenced below to a particular application domain needs to be assessed on a case-by-case basis.

### Example 3. DIDNS Identifier DNS Query Example

| DNS Operation | Example |
| ------------- | ------- |
| DNS Query | ```_diddoc.0e12c4ff-227b-4642-b37f-f1eff9d44914.users.example.com.didns.directory type=ANY``` |
| DNS Response | ```_diddoc TXT "{ \"id\" : \"did:ns:com:example:users:0e12c4ff-227b-4642-b37f-f1eff9d44914\" }"``` |
|  | ```_diddoc TXT "{ \"service\" : [ { \"id\" : \"#agent0\" }, { \"type\": \"default\" }, { \"serviceEndpoint\": \"https://agents.example.com/agent0\" } ] }"``` |
|  | ```_diddoc TXT "{ \"service\" : [ { \"id\" : \"#agent1\" }, { \"type\": \"default\" }, { \"serviceEndpoint\": \"https://agents.example.com/agent1\" } ] }"``` |

![Example 3. DIDNS Identifier DNS Example](images/did-ns-dns-example-1-0-1.png)

![Example 3. DIDNS Identifier DNS Example](images/did-ns-dns-example2-1-0-1.png)

### Security Considerations

Implementers need to be aware of the security and performance implications of the underlying tools and technologies 
used to develop DIDComm agents, services, and libraries that, in turn, leverage the DIDNS Identifier Method Specification; as one example, whether the underlying VDR is configured to support concensus by PoA, PoS, or PoW.

Further, Implementers are strongly encouraged to review the Security Considerations section of the DID Implementation Guide: https://w3c.github.io/did-imp-guide/#security-considerations.

In addition, consult the Security Considerations section of the Decentralized Identifiers (DIDs) (DID-CORE) specification: https://www.w3.org/TR/did-core/#security-considerations.

Lastly, the following list of best-in-class DID Method Specifications should also be consulted:

### Privacy Considerations

The syntax and construction of a DIDNS Identifier and its associated DID Document helps to ensure that no Personally Identifiable Information (PII) or other personal data is exposed by these constructs.

Further, Implementers are strongly encouraged to review the Privacy Considerations section of the DID Implementation Guide: https://w3c.github.io/did-imp-guide/#privacy-considerations.

In addition, consult the Privacy Considerations section of the Decentralized Identifiers (DIDs) (DID-CORE) specification: https://www.w3.org/TR/did-core/#privacy-considerations.

Lastly, the following list of best-in-class DID Method Specifications should also be consulted:

## 6. Reference Implementations

A version of the code for the Decentralized Identifier Name System (DIDNS) reference implementation can be found in the following GitHub project: https://github.com/Web7Foundation/DnsServer. 
This project is the definitive reference implementation of the Decentralized Identifier Name System (DIDNS) and contains compliant reference implementations of 
Web 7.0 apps, DIDComm agents, and services.

## 7. Acknowledgments

The project is gratefully to all the members of the 
DID-CORE, Verifiable Credentials, and Confidential Storage working groups (hosted by W3C and DIF) for their years of support.

## Appendix A. Public Key Algorithm

There are three public key algorithms supported in this document. 
1. ECDSA
2. SM2
3. EdDSA

### ECDSA

The curves that can be used are:

- secp224r1 -- same as nistp224
- secp256r1 -- same as nistp256 
- secp384r1 -- same as nistp384 
- secp521r1 -- same as nistp521

More curves may be supported in future versions of this Method.

### SM2

There is only one curve that can be used, namely, `sm2p256v1` as defined in [SM2 Digital Signature Algorithm](https://tools.ietf.org/html/draft-shen-sm2-ecdsa-02#appendix-D).

### EdDSA

There is only one curve that can be used, namely, `ed25519`.

## References

References and historical record of related publications.

[0] Web 7.0 DIDComm Agent Architecture Reference Model (DIDComm-ARM) 0.40 (December 18, 2022), https://hyperonomy.com/2022/12/18/web-7-0-didcomm-agent-architecture-reference-model-didcomm-arm-0-40-december-18-2022/.