FEP-ef61: Update proposal

- Add "History" section.
- Require verificationMethod of integrity proof to match DID.
- Add "Compatibility" section.
- Change contact address.

ef61/fep-ef61.md

@@ -1,6 +1,6 @@
 ---
 slug: "ef61"
-authors: silverpill <silverpill@firemail.cc>
+authors: silverpill <@silverpill@mitra.social>
 status: DRAFT
 dateReceived: 2023-12-06
 discussionsTo: https://codeberg.org/fediverse/fep/issues/209
@@ -23,6 +23,12 @@ The proposed solution should satisfy the following constraints:
 - The solution should be compatible with existing and emerging decentralized identity and storage systems.
 - The solution should be transport-agnostic.
 
+## History
+
+[Streams](https://codeberg.org/streams/streams) implements [Nomadic Identity](https://codeberg.org/streams/streams/src/commit/11f5174fdd3dfcd8714974f93d8b8fc50378a193/FEDERATION.md?display=source#L54-L59) mechanism, that makes identity independent from a server. Nomadic accounts are currently not supported by ActivityPub but are available via the [Nomad protocol](https://codeberg.org/streams/streams/src/commit/11f5174fdd3dfcd8714974f93d8b8fc50378a193/spec/Nomad/Home.md).
+
+[Decentralized Identifiers (DIDs) v1.0][DID] specification suggests that DIDs might be assigned to web resources in section [B.8 Assigning DIDs to existing web resources](https://www.w3.org/TR/did-core/#assigning-dids-to-existing-web-resources).
+
 ## Requirements
 
 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC-2119][RFC-2119].
@@ -63,7 +69,7 @@ If object identified by `did:ap:key` URL is not stored on a server, it MUST retu
 
 If object is not public, `/.well-known/apresolver` MUST return `404 Not Found` unless the request has a HTTP signature and the signer is allowed to view the object.
 
-After retrieving an object, the client MUST verify its [FEP-8b32][FEP-8b32] integrity proof.
+After retrieving an object, the client MUST verify its [FEP-8b32][FEP-8b32] integrity proof. The value of `verificationMethod` property of the proof MUST match the DID component of the DID URL.
 
 ## Portable actors
 
@@ -166,6 +172,14 @@ Example:
 }
 ```
 
+## Compatibility
+
+DID URLs are not compatible with existing [ActivityPub][ActivityPub] implementations. The following workarounds are being considered:
+
+1. Use HTTP URL of a resolver query instead of an actual DID URL. Implementations that support DID URLs should be able to extract the DID URL from the HTTP URL and process the object accordingly.
+2. Use regular HTTP URLs but include a link to a DID URL in the `url` (with the `canonical` relation type, as proposed in [FEP-fffd][FEP-fffd]).
+3. Alter object ID depending on the capabilities of the peer which can be reported by [NodeInfo][NodeInfo] or some other mechanism.
+
 ## References
 
 - Christine Lemmer Webber, Jessica Tallon, [ActivityPub][ActivityPub], 2018
@@ -174,6 +188,8 @@ Example:
 - Manu Sporny, Dave Longley, Markus Sabadello, Drummond Reed, Orie Steele, Christopher Allen, [Decentralized Identifiers (DIDs) v1.0][DID], 2022
 - silverpill, [FEP-8b32: Object Integrity Proofs][FEP-8b32], 2022
 - silverpill, [FEP-ae97: Client-side activity signing][FEP-ae97], 2023
+- Adam R. Nelson, [FEP-fffd: Proxy Objects][FEP-fffd], 2023
+- Jonne Haß, [NodeInfo][NodeInfo], 2014
 
 [ActivityPub]: https://www.w3.org/TR/activitypub/
 [RFC-2119]: https://tools.ietf.org/html/rfc2119.html
@@ -182,6 +198,8 @@ Example:
 [DID URLs]: https://www.w3.org/TR/did-core/#did-url-syntax
 [FEP-8b32]: https://codeberg.org/fediverse/fep/src/branch/main/fep/8b32/fep-8b32.md
 [FEP-ae97]: https://codeberg.org/fediverse/fep/src/branch/main/fep/ae97/fep-ae97.md
+[FEP-fffd]: https://codeberg.org/fediverse/fep/src/branch/main/fep/fffd/fep-fffd.md
+[NodeInfo]: https://nodeinfo.diaspora.software/
 
 ## Copyright