add encrypted private section to group lists and channels

crates/nip29/src/lib.rs

@@ -6,7 +6,7 @@ use anyhow::{Error, Result};
 use gpui::{App, AppContext, Context, Entity, EventEmitter, Global, Subscription, Task};
 use nostr_sdk::prelude::*;
 use smallvec::{SmallVec, smallvec};
-use state::NostrRegistry;
+use state::{NostrRegistry, UniversalSigner};
 
 mod discovery;
 mod group;
@@ -170,7 +170,7 @@ impl GroupsRegistry {
             return;
         };
 
-        self.upsert_entry(&key, None);
+        self.upsert_entry(&key, None, false);
         self.publish_list(cx);
 
         cx.emit(GroupsEvent::Updated);
@@ -231,6 +231,7 @@ impl GroupsRegistry {
         };
 
         let metadata = options.metadata(name.clone());
+        let list_private = options.list_private;
         let builder = key.id().create_group(None);
         let published = group.read(cx).publish(builder, cx);
         let created = key;
@@ -276,7 +277,7 @@ impl GroupsRegistry {
             }
 
             this.update(cx, |this, cx| {
-                this.upsert_entry(&created, Some(name));
+                this.upsert_entry(&created, Some(name), list_private);
                 this.publish_list(cx);
 
                 cx.emit(GroupsEvent::Updated);
@@ -463,7 +464,10 @@ impl GroupsRegistry {
             let filter = Filter::new().author(me).kind(Kind::SimpleGroups).limit(1);
 
             match client.database().query(filter).await?.into_iter().next() {
-                Some(event) => GroupList::parse(&event),
+                Some(event) => {
+                    let list = GroupList::parse(&event)?;
+                    Ok(Self::hydrate_list(list, &signer, &me).await)
+                }
                 None => Ok(GroupList::default()),
             }
         });
@@ -506,6 +510,10 @@ impl GroupsRegistry {
     }
 
     fn merge(&mut self, list: GroupList, cx: &mut Context<Self>) {
+        // Carry the event's private section so a later publish can preserve it.
+        self.list
+            .set_content(list.content().map(str::to_owned), list.content_readable());
+
         let entries = list.entries().to_vec();
 
         for entry in entries {
@@ -517,6 +525,58 @@ impl GroupsRegistry {
         cx.notify();
     }
 
+    /// Decrypt a list event's private section into its entries.
+    async fn hydrate_list(
+        mut list: GroupList,
+        signer: &UniversalSigner,
+        me: &PublicKey,
+    ) -> GroupList {
+        let Some(content) = list.content().map(str::to_owned) else {
+            return list;
+        };
+
+        match signer.nip44_decrypt(me, &content).await {
+            Ok(plaintext) => match parse_private_section(&plaintext) {
+                Some(entries) => {
+                    list.merge_private(entries);
+                    list.mark_readable();
+                }
+                None => log::warn!("ignoring a malformed private group list section"),
+            },
+            Err(error) => log::warn!("decrypting the private group list failed: {error}"),
+        }
+
+        list
+    }
+
+    /// Absorb a list event, decrypting its private section off the hot path.
+    fn absorb_list(&mut self, event: Event, cx: &mut Context<Self>) {
+        let list = match GroupList::parse(&event) {
+            Ok(list) => list,
+            Err(error) => {
+                log::warn!("ignoring a malformed group list: {error}");
+                return;
+            }
+        };
+
+        if list.content().is_none() {
+            self.merge(list, cx);
+            return;
+        }
+
+        let nostr = NostrRegistry::global(cx);
+        let signer = nostr.read(cx).signer();
+        let Some(me) = nostr.read(cx).current_user() else {
+            self.merge(list, cx);
+            return;
+        };
+
+        self.tasks.push(cx.spawn(async move |this, cx| {
+            let list = Self::hydrate_list(list, &signer, &me).await;
+            this.update(cx, |this, cx| this.merge(list, cx)).ok();
+        }));
+    }
+
     fn watch_forks(&mut self, cx: &mut Context<Self>) {
         let executor = cx.background_executor().clone();
         let tx = self.signal_tx.clone();
@@ -733,13 +793,14 @@ impl GroupsRegistry {
             .and_then(|entry| entry.name.clone())
     }
 
-    fn upsert_entry(&mut self, key: &GroupKey, name: Option<String>) {
+    fn upsert_entry(&mut self, key: &GroupKey, name: Option<String>, private: bool) {
         let name = name.or_else(|| self.entry_name(key));
 
         self.list.upsert(GroupListEntry {
             id: key.id().clone(),
             relay: key.relay().clone(),
             name,
+            private,
         });
     }
 
@@ -761,7 +822,9 @@ impl GroupsRegistry {
             return;
         }
 
-        self.upsert_entry(&key, Some(name));
+        let private = self.list.entry(&key).is_some_and(|entry| entry.private);
+
+        self.upsert_entry(&key, Some(name), private);
         self.publish_list(cx);
     }
 
@@ -769,10 +832,30 @@ impl GroupsRegistry {
         let nostr = NostrRegistry::global(cx);
         let client = nostr.read(cx).client();
         let signer = nostr.read(cx).signer();
-
-        let builder = self.list.to_builder();
+        let me = nostr.read(cx).current_user();
+        let list = self.list.clone();
 
         self.tasks.push(cx.spawn(async move |_this, _cx| {
+            // Re-encrypt the private section when it carries local entries; a
+            // section this session could not read is carried verbatim.
+            let content = match (list.has_private(), list.content_readable()) {
+                (true, _) => match list.encode_private().zip(me) {
+                    Some((plaintext, me)) => match signer.nip44_encrypt(&me, &plaintext).await {
+                        Ok(content) => Some(content),
+                        Err(error) => {
+                            log::warn!("encrypting the private group list failed: {error}");
+                            list.content().map(str::to_owned)
+                        }
+                    },
+                    None => None,
+                },
+                (false, false) => list.content().map(str::to_owned),
+                (false, true) => None,
+            };
+
+            let builder = EventBuilder::new(Kind::SimpleGroups, content.unwrap_or_default())
+                .tags(list.public_tags());
+
             let event = match builder.finalize_async(&signer).await {
                 Ok(event) => event,
                 Err(error) => {
@@ -929,10 +1012,7 @@ impl GroupsRegistry {
 
     fn handle_event(&mut self, id: SubscriptionId, event: Event, cx: &mut Context<Self>) {
         if id == list_subscription_id() {
-            match GroupList::parse(&event) {
-                Ok(list) => self.merge(list, cx),
-                Err(error) => log::warn!("ignoring a malformed group list: {error}"),
-            }
+            self.absorb_list(event, cx);
             return;
         }
 

crates/nip29/src/protocol.rs

@@ -445,6 +445,8 @@ pub struct GroupCreateOptions {
     pub closed: bool,
     pub restricted: bool,
     pub hidden: bool,
+    /// List the group in the NIP-44 encrypted section of the user's group list.
+    pub list_private: bool,
     pub custom_id: Option<String>,
     pub parent: Option<GroupId>,
 }
@@ -641,10 +643,19 @@ pub(crate) struct GroupListEntry {
     pub id: GroupId,
     pub relay: RelayUrl,
     pub name: Option<String>,
+    /// Kept in the encrypted section of the list event, not in public tags.
+    pub private: bool,
 }
 
 #[derive(Debug, Clone, Default)]
-pub(crate) struct GroupList(Vec<GroupListEntry>);
+pub(crate) struct GroupList {
+    entries: Vec<GroupListEntry>,
+    /// The raw private section of the last seen list event.
+    content: Option<String>,
+    /// Whether the content was decrypted in this session; an opaque section
+    /// (another client's encryption, or a refused decrypt) is carried verbatim.
+    readable: bool,
+}
 
 impl GroupList {
     pub fn parse(event: &Event) -> Result<Self> {
@@ -672,36 +683,94 @@ impl GroupList {
                 id,
                 relay,
                 name: fields.get(3).cloned(),
+                private: false,
             });
         }
 
-        Ok(Self(entries))
+        let content = if event.content.is_empty() {
+            None
+        } else {
+            Some(event.content.clone())
+        };
+
+        Ok(Self {
+            entries,
+            readable: content.is_none(),
+            content,
+        })
     }
 
     pub fn entries(&self) -> &[GroupListEntry] {
-        &self.0
+        &self.entries
+    }
+
+    pub fn entry(&self, key: &GroupKey) -> Option<&GroupListEntry> {
+        self.entries
+            .iter()
+            .find(|entry| entry.id == *key.id() && entry.relay == *key.relay())
     }
 
     pub fn upsert(&mut self, entry: GroupListEntry) {
         match self
-            .0
+            .entries
             .iter_mut()
             .find(|existing| existing.id == entry.id && existing.relay == entry.relay)
         {
             Some(existing) => *existing = entry,
-            None => self.0.push(entry),
+            None => self.entries.push(entry),
         }
     }
 
     pub fn remove(&mut self, key: &GroupKey) {
-        self.0
+        self.entries
             .retain(|entry| entry.id != *key.id() || entry.relay != *key.relay());
     }
 
-    pub fn to_builder(&self) -> EventBuilder {
-        let mut tags: Vec<Tag> = Vec::with_capacity(self.0.len() * 2);
+    /// The raw private section of the list event, if any.
+    pub(crate) fn content(&self) -> Option<&str> {
+        self.content.as_deref()
+    }
+
+    pub(crate) fn content_readable(&self) -> bool {
+        self.readable
+    }
+
+    pub(crate) fn set_content(&mut self, content: Option<String>, readable: bool) {
+        self.content = content;
+        self.readable = readable;
+    }
+
+    pub(crate) fn has_private(&self) -> bool {
+        self.entries.iter().any(|entry| entry.private)
+    }
+
+    /// Mark the private section as readable after a successful decrypt.
+    pub(crate) fn mark_readable(&mut self) {
+        self.readable = true;
+    }
+
+    /// Add decrypted private entries; the public listing wins on collision.
+    pub(crate) fn merge_private(&mut self, entries: Vec<GroupListEntry>) {
+        for entry in entries {
+            let public = self.entries.iter().any(|existing| {
+                !existing.private && existing.id == entry.id && existing.relay == entry.relay
+            });
+
+            if !public {
+                self.upsert(entry);
+            }
+        }
+    }
+
+    /// The tags of the public section of the list event.
+    pub(crate) fn public_tags(&self) -> Vec<Tag> {
+        let mut tags = Vec::with_capacity(self.entries.len() * 2);
+
+        for entry in &self.entries {
+            if entry.private {
+                continue;
+            }
 
-        for entry in &self.0 {
             let mut values = vec![
                 entry.id.as_str().to_owned(),
                 entry.relay.as_str().to_owned(),
@@ -715,8 +784,68 @@ impl GroupList {
             tags.push(Tag::custom("r", [entry.relay.as_str()]));
         }
 
-        EventBuilder::new(Kind::SimpleGroups, "").tags(tags)
+        tags
     }
+
+    /// The private entries encoded as a tag array, ready for encryption.
+    pub(crate) fn encode_private(&self) -> Option<String> {
+        let tags: Vec<Vec<String>> = self
+            .entries
+            .iter()
+            .filter(|entry| entry.private)
+            .map(|entry| {
+                let mut values = vec![
+                    entry.id.as_str().to_owned(),
+                    entry.relay.as_str().to_owned(),
+                ];
+
+                if let Some(name) = &entry.name {
+                    values.push(name.clone());
+                }
+
+                values
+            })
+            .collect();
+
+        if tags.is_empty() {
+            None
+        } else {
+            serde_json::to_string(&tags).ok()
+        }
+    }
+}
+
+/// Parse a decrypted private section; `None` when it isn't a tag array.
+pub(crate) fn parse_private_section(plaintext: &str) -> Option<Vec<GroupListEntry>> {
+    let tags = serde_json::from_str::<Vec<Vec<String>>>(plaintext).ok()?;
+
+    let mut entries = Vec::new();
+
+    for tag in tags {
+        if tag.first().map(String::as_str) != Some("group") {
+            continue;
+        }
+
+        let (Some(id), Some(relay)) = (tag.get(1), tag.get(2)) else {
+            continue;
+        };
+
+        let Ok(id) = GroupId::new(id) else {
+            continue;
+        };
+        let Ok(relay) = RelayUrl::parse(relay) else {
+            continue;
+        };
+
+        entries.push(GroupListEntry {
+            id,
+            relay,
+            name: tag.get(3).cloned(),
+            private: true,
+        });
+    }
+
+    Some(entries)
 }
 
 #[derive(Debug, Clone, PartialEq, Eq)]