feat(59/STATUS-URL-DATA): initial draft (#13)

Moved from https://github.com/status-im/specs/pull/169

Reference pull request: https://github.com/vacp2p/rfc/pull/600

---------

Co-authored-by: Felicio Mununga <felicio@users.noreply.github.com>

status/raw/url-data.md

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+---
+title: STATUS-URL-DATA
+name: Status URL Data
+status: raw
+category: Standards Track
+tags:
+editor: Felicio Mununga <felicio@status.im>
+contributors:
+  - Aaryamann Challani <aaryamann@status.im>
+---
+
+## Abstract
+
+This document specifies serialization, compression, and
+encoding techniques used to transmit data within URLs in the context of Status protocols.
+
+## Motivation
+
+When sharing URLs,
+link previews often expose metadata to the websites behind those links.
+To reduce reliance on external servers for providing appropriate link previews,
+this specification proposes a standard method for encoding data within URLs.
+
+## Terminology
+
+- Community: Refer to [STATUS-COMMUNITIES](../56/communities.md)
+- Channel: Refer to terminology in [STATUS-COMMUNITIES](../56/communities.md)
+- User: Refer to terminology in [STATUS-COMMUNITIES](../56/communities.md)
+- Shard Refer to terminology in [51/WAKU2-RELAY-SHARDING](https://github.com/waku-org/specs/blob/master/standards/core/relay-sharding.md)
+
+## Wire Format
+
+```protobuf
+syntax = "proto3";
+
+message Community {
+    // Display name of the community
+    string display_name = 1;
+    // Description of the community
+    string description = 2;
+    // Number of members in the community
+    uint32 members_count = 3;
+    // Color of the community title
+    string color = 4;
+    // List of tag indices
+    repeated uint32 tag_indices = 5;
+}
+
+message Channel {
+    // Display name of the channel
+    string display_name = 1;
+    // Description of the channel
+    string description = 2;
+    // Emoji of the channel
+    string emoji = 3;
+    // Color of the channel title
+    string color = 4;
+    // Community the channel belongs to
+    Community community = 5;
+    // UUID of the channel
+    string uuid = 6;
+}
+
+message User {
+    // Display name of the user
+    string display_name = 1;
+    // Description of the user
+    string description = 2;
+    // Color of the user title
+    string color = 3;
+}
+
+message URLData {
+    // Community, Channel, or User
+    bytes content = 1;
+    uint32 shard_cluster = 2;
+    uint32 shard_index = 3;
+}
+```
+
+## Implementation
+
+The above wire format describes the data encoded in the URL.
+The data MUST be serialized, compressed, and encoded using the following standards:
+
+Encoding
+
+- [Base64url](https://datatracker.ietf.org/doc/html/rfc4648)
+
+### Compression
+
+- [Brotli](https://datatracker.ietf.org/doc/html/rfc7932)
+
+### Serialization
+
+- [Protocol buffers version 3](https://protobuf.dev/reference/protobuf/proto3-spec/)
+
+### Implementation Pseudocode
+
+Encoding
+
+Encoding the URL MUST be done in the following order:
+
+```protobuf
+raw_data = {User | Channel | Community}
+serialized_data = protobuf_serialize(raw_data)
+compressed_data = brotli_compress(serialized_data)
+encoded_url_data = base64url_encode(compressed_data)
+```
+
+The `encoded_url_data` is then used to generate a signature using the private key.
+
+#### Decoding
+
+Decoding the URL MUST be done in the following order:
+
+```protobuf
+url_data = base64url_decode(encoded_url_data)
+decompressed_data = brotli_decompress(url_data)
+deserialized_data = protobuf_deserialize(decompressed_data)
+raw_data = deserialized_data.content
+```
+
+The `raw_data` is then used to construct the appropriate data structure
+(User, Channel, or Community).
+
+### Example
+
+- See <https://github.com/status-im/status-web/pull/345/files>
+
+<!-- # (Further Optional Sections) -->
+
+## Discussions
+
+- See <https://github.com/status-im/status-web/issues/327>
+
+## Proof of concept
+
+- See <https://github.com/felicio/status-web/blob/825262c4f07a68501478116c7382862607a5544e/packages/status-js/src/utils/encode-url-data.compare.test.ts#L4>
+
+<!-- # Security Considerations -->
+
+## Copyright
+
+Copyright and related rights waived via [CC0](https://creativecommons.org/publicdomain/zero/1.0/).
+
+## References
+
+1. [Proposal Google Sheet](https://docs.google.com/spreadsheets/d/1JD4kp0aUm90piUZ7FgM_c2NGe2PdN8BFB11wmt5UZIY/edit?usp=sharing)
+2. [Base64url](https://datatracker.ietf.org/doc/html/rfc4648)
+3. [Brotli](https://datatracker.ietf.org/doc/html/rfc7932)
+4. [Protocol buffers version 3](https://protobuf.dev/reference/protobuf/proto3-spec/)
+5. [STATUS-URL-SCHEME](./url-scheme.md)
+
+<!-- ## informative
+
+A list of additional references. -->