backend/src/app.rs

@@ -66,6 +66,8 @@ pub fn build_app(state: AppState) -> Router {
             get(handlers::list_shares).post(handlers::create_share),
         )
         .route("/api/profiles/:id/shares/:recipient", delete(handlers::delete_share))
+        // Hard revoke / rotate the profile DEK (Phase C). Owner-only.
+        .route("/api/profiles/:id/rekey", post(handlers::rekey_profile))
         // Session management (Phase 2.6)
         .route("/api/sessions", get(handlers::get_sessions))
         .route("/api/sessions/:id", delete(handlers::revoke_session))

backend/src/handlers/mod.rs

@@ -26,7 +26,7 @@ pub use medications::{
 pub use profile::{create_profile, delete_profile, get_profile, list_profiles, update_profile};
 pub use profile_share::{
     create_share, delete_share, get_profile_shared_aware, get_public_key, list_shared_with_me,
-    list_shares,
+    list_shares, rekey_profile,
 };
 pub use sessions::{get_sessions, revoke_all_sessions, revoke_session};
 pub use users::{

backend/src/handlers/profile_share.rs

@@ -511,3 +511,198 @@ pub async fn get_public_key(
         identity_public_key: pk,
     }))
 }
+
+// ---------------------------------------------------------------------------
+// POST /api/profiles/:id/rekey — hard revoke / rotate the profile DEK (Phase C).
+//
+// The owner's client has already (a) generated a fresh profile DEK, (b)
+// re-encrypted all the profile's data under it (client-side), and (c) wrapped
+// the new DEK to its own account DEK + to each still-valid recipient's identity
+// public key via fresh ECDH envelopes. This call commits the rotation: it
+// stores the new owner-wrapped DEK, upserts each submitted recipient envelope,
+// and hard-deletes any current recipient NOT in the submitted list (the
+// hard-revoke). The server stores only opaque blobs + public keys.
+// ---------------------------------------------------------------------------
+
+#[derive(Debug, Deserialize)]
+pub struct RecipientEnvelope {
+    pub recipient_user_id: String,
+    pub ephemeral_public_key: String,
+    pub wrapped_profile_dek: String,
+    pub wrapped_profile_dek_iv: String,
+}
+
+#[derive(Debug, Deserialize)]
+pub struct RekeyRequest {
+    /// The NEW profile DEK, wrapped under the owner's account DEK. Opaque.
+    pub new_wrapped_profile_dek: String,
+    pub new_wrapped_profile_dek_iv: String,
+    /// One fresh ECDH envelope per recipient the owner wants to KEEP. Any
+    /// current recipient not listed here is hard-revoked.
+    #[serde(default)]
+    pub recipient_envelopes: Vec<RecipientEnvelope>,
+}
+
+#[derive(Debug, Serialize)]
+pub struct RekeyResponse {
+    pub profile_id: String,
+    pub wrapped_profile_dek: String,
+    pub wrapped_profile_dek_iv: String,
+    /// The recipients still sharing this profile after the rotation.
+    pub retained_recipient_user_ids: Vec<String>,
+}
+
+pub async fn rekey_profile(
+    State(state): State<AppState>,
+    Extension(claims): Extension<Claims>,
+    Path(profile_id): Path<String>,
+    Json(req): Json<RekeyRequest>,
+) -> Result<(StatusCode, Json<RekeyResponse>), (StatusCode, Json<serde_json::Value>)> {
+    // 1. Owner-only. (Admin-tier rekey is reserved for a later phase; the
+    //    handler is owner-only for now.)
+    let profiles = profile_repo(&state);
+    let owner = match profiles
+        .find_by_profile_id_owned(&profile_id, &claims.sub)
+        .await
+    {
+        Ok(Some(p)) => p.owner_account_id,
+        Ok(None) => {
+            return Err((
+                StatusCode::NOT_FOUND,
+                Json(serde_json::json!({ "error": "profile not found" })),
+            ));
+        }
+        Err(e) => {
+            tracing::error!("rekey profile lookup failed: {}", e);
+            return Err((
+                StatusCode::INTERNAL_SERVER_ERROR,
+                Json(serde_json::json!({ "error": "database error" })),
+            ));
+        }
+    };
+
+    // 2. Validate each submitted envelope: the owner can only rotate envelopes
+    //    for recipients who ALREADY have an active share. (Adding a new share
+    //    goes through POST /profiles/:id/shares, not rekey.) This prevents
+    //    smuggling in a brand-new recipient via the rekey call.
+    let shares = share_repo(&state);
+    let active_shares = match shares.find_active_for_profile(&profile_id).await {
+        Ok(v) => v,
+        Err(e) => {
+            tracing::error!("rekey active-share lookup failed: {}", e);
+            return Err((
+                StatusCode::INTERNAL_SERVER_ERROR,
+                Json(serde_json::json!({ "error": "database error" })),
+            ));
+        }
+    };
+    let active_recipient_ids: std::collections::HashSet<&str> = active_shares
+        .iter()
+        .map(|s| s.recipient_user_id.as_str())
+        .collect();
+    for env in &req.recipient_envelopes {
+        if !active_recipient_ids.contains(env.recipient_user_id.as_str()) {
+            return Err((
+                StatusCode::BAD_REQUEST,
+                Json(serde_json::json!({
+                    "error": "recipient_envelope references a recipient with no active share; use POST /profiles/:id/shares to add a share",
+                    "recipient_user_id": env.recipient_user_id,
+                })),
+            ));
+        }
+    }
+
+    // 3. Rotate the owner share (store the new account-wrapped profile DEK).
+    // update_wrapped_dek uses find_one_and_update, which returns the PRE-image
+    // by default — so we don't read the new values back from it; we echo the
+    // request values (exactly what was stored) in the response below.
+    match profiles
+        .update_wrapped_dek(
+            &profile_id,
+            &owner,
+            &req.new_wrapped_profile_dek,
+            &req.new_wrapped_profile_dek_iv,
+        )
+        .await
+    {
+        Ok(Some(_)) => {}
+        Ok(None) => {
+            return Err((
+                StatusCode::NOT_FOUND,
+                Json(serde_json::json!({ "error": "profile not found" })),
+            ));
+        }
+        Err(e) => {
+            tracing::error!("rekey owner-share rotation failed: {}", e);
+            return Err((
+                StatusCode::INTERNAL_SERVER_ERROR,
+                Json(serde_json::json!({ "error": "database error" })),
+            ));
+        }
+    }
+
+    // 4. Upsert each submitted recipient envelope (fresh ECDH-wrapped DEK +
+    //    ephemeral pubkey, replacing the old envelope). Preserve the original
+    //    share's permissions / expires_at by reading them from the active share.
+    let now = DateTime::now();
+    for env in &req.recipient_envelopes {
+        let original = active_shares
+            .iter()
+            .find(|s| s.recipient_user_id == env.recipient_user_id);
+        let permissions = original
+            .map(|s| s.permissions.clone())
+            .unwrap_or_else(|| vec!["read".to_string()]);
+        let expires_at = original.and_then(|s| s.expires_at);
+        let new_share = ProfileShare {
+            id: None,
+            profile_id: profile_id.clone(),
+            owner_user_id: owner.clone(),
+            recipient_user_id: env.recipient_user_id.clone(),
+            ephemeral_public_key: env.ephemeral_public_key.clone(),
+            wrapped_profile_dek: env.wrapped_profile_dek.clone(),
+            wrapped_profile_dek_iv: env.wrapped_profile_dek_iv.clone(),
+            permissions,
+            expires_at,
+            created_at: now,
+            active: true,
+        };
+        if let Err(e) = shares.upsert(&new_share).await {
+            tracing::error!("rekey recipient upsert failed: {}", e);
+            return Err((
+                StatusCode::INTERNAL_SERVER_ERROR,
+                Json(serde_json::json!({ "error": "database error" })),
+            ));
+        }
+    }
+
+    // 5. Hard-revoke any current recipient NOT in the submitted list. Their
+    //    cached old DEK no longer matches the rotated profile DEK, AND the
+    //    server stops serving them.
+    let keep: Vec<String> = req
+        .recipient_envelopes
+        .iter()
+        .map(|e| e.recipient_user_id.clone())
+        .collect();
+    if let Err(e) = shares
+        .delete_for_profile_excluding(&profile_id, &keep)
+        .await
+    {
+        tracing::error!("rekey hard-revoke delete failed: {}", e);
+        return Err((
+            StatusCode::INTERNAL_SERVER_ERROR,
+            Json(serde_json::json!({ "error": "database error" })),
+        ));
+    }
+
+    Ok((
+        StatusCode::OK,
+        Json(RekeyResponse {
+            profile_id,
+            // Echo the request values (exactly what was stored). Avoids the
+            // find_one_and_update pre-image gotcha.
+            wrapped_profile_dek: req.new_wrapped_profile_dek,
+            wrapped_profile_dek_iv: req.new_wrapped_profile_dek_iv,
+            retained_recipient_user_ids: keep,
+        }),
+    ))
+}

backend/src/models/profile.rs

@@ -152,6 +152,31 @@ impl ProfileRepository {
             .await
     }
 
+    /// Rotate the profile's wrapped DEK (owner share) — Phase C hard revoke.
+    /// Stores the new account-wrapped profile DEK verbatim, keyed by
+    /// (profile_id, owner). Returns the updated profile or None if it doesn't
+    /// exist / isn't owned by `owner`. The server stores the opaque blob
+    /// verbatim and cannot decrypt it.
+    pub async fn update_wrapped_dek(
+        &self,
+        profile_id: &str,
+        owner: &str,
+        new_wrapped_profile_dek: &str,
+        new_wrapped_profile_dek_iv: &str,
+    ) -> mongodb::error::Result<Option<Profile>> {
+        self.collection
+            .find_one_and_update(
+                doc! { "profileId": profile_id, "ownerAccountId": owner },
+                doc! { "$set": {
+                    "wrappedProfileDek": new_wrapped_profile_dek,
+                    "wrappedProfileDekIv": new_wrapped_profile_dek_iv,
+                    "updatedAt": DateTime::now()
+                }},
+                None,
+            )
+            .await
+    }
+
     /// Delete a profile keyed by (profile_id, owner). Returns true if a doc
     /// was deleted, false if it didn't exist or wasn't owned by `owner`.
     pub async fn delete_profile(

backend/src/models/profile_share.rs

@@ -142,6 +142,49 @@ impl ProfileShareRepository {
         self.collection.find_one(filter, None).await
     }
 
+    /// All currently-active shares for a profile (Phase C rekey needs the full
+    /// recipient list to validate submitted envelopes and hard-delete omitted
+    /// recipients). "Active" = `active==true` and not past `expires_at`.
+    pub async fn find_active_for_profile(
+        &self,
+        profile_id: &str,
+    ) -> mongodb::error::Result<Vec<ProfileShare>> {
+        let now = DateTime::now();
+        let filter = doc! {
+            "profileId": profile_id,
+            "active": true,
+            "$or": [
+                { "expiresAt": { "$exists": false } },
+                { "expiresAt": null },
+                { "expiresAt": { "$gt": now } },
+            ],
+        };
+        let mut cursor = self.collection.find(filter, None).await?;
+        let mut out = Vec::new();
+        while let Some(s) = cursor.next().await {
+            out.push(s?);
+        }
+        Ok(out)
+    }
+
+    /// Hard-delete every share for the profile whose recipient is NOT in
+    /// `keep_recipient_ids` — the hard-revoke action in Phase C rekey. Recipients
+    /// omitted from the rekey call lose access at the key level (their cached
+    /// old DEK won't match the rotated one) AND the server stops serving them.
+    /// Returns the number deleted.
+    pub async fn delete_for_profile_excluding(
+        &self,
+        profile_id: &str,
+        keep_recipient_ids: &[String],
+    ) -> mongodb::error::Result<u64> {
+        let mut filter = doc! { "profileId": profile_id };
+        if !keep_recipient_ids.is_empty() {
+            filter.insert("recipientUserId", doc! { "$nin": keep_recipient_ids });
+        }
+        let res = self.collection.delete_many(filter, None).await?;
+        Ok(res.deleted_count)
+    }
+
     /// Hard-delete (soft-revoke) the (profile, recipient) share. Returns true
     /// if a doc was deleted.
     pub async fn delete(

backend/tests/rekey_tests.rs

@@ -0,0 +1,382 @@
+//! Hard-revoke / re-key integration tests (Phase C).
+//!
+//! Verifies POST /api/profiles/:id/rekey: rotating the profile's wrapped DEK,
+//! upserting submitted recipient envelopes (fresh ECDH wraps), and hard-
+//! deleting any current recipient NOT in the submitted list. Wire-level only
+//! (opaque blobs — the server never inspects them, so the tests don't need
+//! real crypto).
+//!
+//! Requires a live MongoDB; skips gracefully otherwise.
+
+mod common;
+
+use serde_json::{json, Value};
+
+macro_rules! require_app {
+    ($app:expr) => {
+        match $app {
+            Some(x) => x,
+            None => {
+                eprintln!("[integration] skipped (MongoDB unavailable)");
+                return;
+            }
+        }
+    };
+}
+
+fn unique_email() -> String {
+    format!("test_{}@example.com", uuid::Uuid::new_v4())
+}
+
+/// Register a fully-set-up user (identity key + default self profile).
+async fn register_full(app: &axum::Router, email: &str) -> Value {
+    let (status, body) = common::send_json(
+        app,
+        "POST",
+        "/api/auth/register",
+        Some(json!({
+            "email": email,
+            "username": email,
+            "password": "supersecret",
+            "identity_public_key": format!("pub-{email}"),
+            "default_profile_name_data": "n",
+            "default_profile_name_iv": "i",
+            "default_wrapped_profile_dek": "owner-dek-v1",
+            "default_wrapped_profile_dek_iv": "owner-dek-iv-v1",
+        })),
+        None,
+    )
+    .await;
+    assert_eq!(status, 201, "register_full failed, body: {body}");
+    body
+}
+
+fn token(body: &Value) -> String {
+    body["token"].as_str().unwrap().to_string()
+}
+
+fn self_profile_id(body: &Value) -> String {
+    format!("profile_{}", body["user_id"].as_str().unwrap())
+}
+
+/// Owner shares profile to recipient_email; returns the recipient's user_id
+/// (looked up from the share listing afterward).
+async fn share_to(
+    app: &axum::Router,
+    owner_token: &str,
+    profile_id: &str,
+    recipient_email: &str,
+) -> String {
+    let (status, _) = common::send_json(
+        app,
+        "POST",
+        &format!("/api/profiles/{profile_id}/shares"),
+        Some(json!({
+            "recipient_email": recipient_email,
+            "ephemeral_public_key": format!("eph-{recipient_email}"),
+            "wrapped_profile_dek": format!("wrap-{recipient_email}"),
+            "wrapped_profile_dek_iv": "iv",
+            "permissions": ["read"],
+        })),
+        Some(owner_token),
+    )
+    .await;
+    assert_eq!(status, 201, "share_to failed");
+    // Look up the recipient's user_id from the listing.
+    let (_, listing) = common::send_json(
+        app,
+        "GET",
+        &format!("/api/profiles/{profile_id}/shares"),
+        None,
+        Some(owner_token),
+    )
+    .await;
+    listing
+        .as_array()
+        .unwrap()
+        .iter()
+        .find(|s| s["recipient_email"] == recipient_email)
+        .unwrap()["recipient_user_id"]
+        .as_str()
+        .unwrap()
+        .to_string()
+}
+
+#[tokio::test]
+async fn rekey_rotates_owner_share_and_keeps_listed_recipients() {
+    let (app, db_name) = require_app!(common::app_for_test().await);
+    let owner_body = register_full(&app, &unique_email()).await;
+    let owner_token = token(&owner_body);
+    let profile_id = self_profile_id(&owner_body);
+
+    let recipient_b = unique_email();
+    let recipient_c = unique_email();
+    register_full(&app, &recipient_b).await;
+    register_full(&app, &recipient_c).await;
+    let b_uid = share_to(&app, &owner_token, &profile_id, &recipient_b).await;
+    let _c_uid = share_to(&app, &owner_token, &profile_id, &recipient_c).await;
+
+    // Owner rekeys: keeps B (fresh envelope), omits C (hard-revoke).
+    let (status, body) = common::send_json(
+        &app,
+        "POST",
+        &format!("/api/profiles/{profile_id}/rekey"),
+        Some(json!({
+            "new_wrapped_profile_dek": "owner-dek-v2",
+            "new_wrapped_profile_dek_iv": "owner-dek-iv-v2",
+            "recipient_envelopes": [{
+                "recipient_user_id": b_uid,
+                "ephemeral_public_key": "eph-b-v2",
+                "wrapped_profile_dek": "wrap-b-v2",
+                "wrapped_profile_dek_iv": "iv-v2",
+            }],
+        })),
+        Some(&owner_token),
+    )
+    .await;
+    assert_eq!(status, 200, "rekey should return 200, body: {body}");
+    // Owner share rotated.
+    assert_eq!(body["wrapped_profile_dek"], "owner-dek-v2");
+    assert_eq!(body["wrapped_profile_dek_iv"], "owner-dek-iv-v2");
+    // Retained = [B].
+    let retained: Vec<&str> = body["retained_recipient_user_ids"]
+        .as_array()
+        .unwrap()
+        .iter()
+        .map(|v| v.as_str().unwrap())
+        .collect();
+    assert_eq!(retained, vec![b_uid.as_str()]);
+
+    // The profile's stored owner-share reflects v2.
+    let (_, profile_body) = common::send_json(
+        &app,
+        "GET",
+        &format!("/api/profiles/{profile_id}"),
+        None,
+        Some(&owner_token),
+    )
+    .await;
+    assert_eq!(profile_body["wrapped_profile_dek"], "owner-dek-v2");
+
+    common::drop_test_db(&db_name).await;
+}
+
+#[tokio::test]
+async fn rekey_hard_revokes_omitted_recipient() {
+    let (app, db_name) = require_app!(common::app_for_test().await);
+    let owner_body = register_full(&app, &unique_email()).await;
+    let owner_token = token(&owner_body);
+    let profile_id = self_profile_id(&owner_body);
+
+    let recipient_b = unique_email();
+    let recipient_c = unique_email();
+    let b_body = register_full(&app, &recipient_b).await;
+    let c_body = register_full(&app, &recipient_c).await;
+    let b_token = token(&b_body);
+    let c_token = token(&c_body);
+    let b_uid = share_to(&app, &owner_token, &profile_id, &recipient_b).await;
+    let _c_uid = share_to(&app, &owner_token, &profile_id, &recipient_c).await;
+
+    // Before rekey: both recipients see the profile in shared-with-me.
+    let (_, shared_before) = common::send_json(
+        &app,
+        "GET",
+        "/api/profiles/shared-with-me",
+        None,
+        Some(&c_token),
+    )
+    .await;
+    assert_eq!(
+        shared_before.as_array().unwrap().len(),
+        1,
+        "C should see the shared profile before rekey"
+    );
+
+    // Rekey keeping only B.
+    let (status, _) = common::send_json(
+        &app,
+        "POST",
+        &format!("/api/profiles/{profile_id}/rekey"),
+        Some(json!({
+            "new_wrapped_profile_dek": "owner-dek-v2",
+            "new_wrapped_profile_dek_iv": "owner-dek-iv-v2",
+            "recipient_envelopes": [{
+                "recipient_user_id": b_uid,
+                "ephemeral_public_key": "eph-b-v2",
+                "wrapped_profile_dek": "wrap-b-v2",
+                "wrapped_profile_dek_iv": "iv-v2",
+            }],
+        })),
+        Some(&owner_token),
+    )
+    .await;
+    assert_eq!(status, 200);
+
+    // B (kept) still sees it, with the rotated envelope.
+    let (_, shared_b) = common::send_json(
+        &app,
+        "GET",
+        "/api/profiles/shared-with-me",
+        None,
+        Some(&b_token),
+    )
+    .await;
+    let arr_b = shared_b.as_array().unwrap();
+    assert_eq!(arr_b.len(), 1, "B sees exactly the one shared profile");
+    assert_eq!(
+        arr_b[0]["wrapped_profile_dek"], "wrap-b-v2",
+        "B's envelope rotated"
+    );
+
+    // C (omitted) no longer sees it.
+    let (_, shared_c) = common::send_json(
+        &app,
+        "GET",
+        "/api/profiles/shared-with-me",
+        None,
+        Some(&c_token),
+    )
+    .await;
+    assert_eq!(
+        shared_c.as_array().unwrap().len(),
+        0,
+        "C must be hard-revoked from shared-with-me"
+    );
+    // And the share-gate 404s C on direct read.
+    let (status, _) = common::send_json(
+        &app,
+        "GET",
+        &format!("/api/profiles/{profile_id}"),
+        None,
+        Some(&c_token),
+    )
+    .await;
+    assert_eq!(
+        status, 404,
+        "C must be denied by the gate after hard revoke"
+    );
+
+    common::drop_test_db(&db_name).await;
+}
+
+#[tokio::test]
+async fn rekey_rejects_envelope_for_recipient_with_no_share() {
+    let (app, db_name) = require_app!(common::app_for_test().await);
+    let owner_body = register_full(&app, &unique_email()).await;
+    let owner_token = token(&owner_body);
+    let profile_id = self_profile_id(&owner_body);
+
+    // A recipient who was never shared with.
+    let stranger_body = register_full(&app, &unique_email()).await;
+    let stranger_uid = stranger_body["user_id"].as_str().unwrap().to_string();
+
+    let (status, body) = common::send_json(
+        &app,
+        "POST",
+        &format!("/api/profiles/{profile_id}/rekey"),
+        Some(json!({
+            "new_wrapped_profile_dek": "owner-dek-v2",
+            "new_wrapped_profile_dek_iv": "owner-dek-iv-v2",
+            "recipient_envelopes": [{
+                "recipient_user_id": stranger_uid,
+                "ephemeral_public_key": "x",
+                "wrapped_profile_dek": "y",
+                "wrapped_profile_dek_iv": "z",
+            }],
+        })),
+        Some(&owner_token),
+    )
+    .await;
+    assert_eq!(
+        status, 400,
+        "envelope for a recipient with no share must be rejected: {body}"
+    );
+
+    common::drop_test_db(&db_name).await;
+}
+
+#[tokio::test]
+async fn rekey_rejects_non_owner() {
+    let (app, db_name) = require_app!(common::app_for_test().await);
+    let owner_body = register_full(&app, &unique_email()).await;
+    let profile_id = self_profile_id(&owner_body);
+
+    let other_token = token(&register_full(&app, &unique_email()).await);
+
+    let (status, _) = common::send_json(
+        &app,
+        "POST",
+        &format!("/api/profiles/{profile_id}/rekey"),
+        Some(json!({
+            "new_wrapped_profile_dek": "x",
+            "new_wrapped_profile_dek_iv": "y",
+            "recipient_envelopes": [],
+        })),
+        Some(&other_token),
+    )
+    .await;
+    assert_eq!(status, 404, "non-owner rekey must be rejected");
+
+    // Profile is unchanged.
+    let (_, profile_body) = common::send_json(
+        &app,
+        "GET",
+        &format!("/api/profiles/{profile_id}"),
+        None,
+        Some(token(&owner_body).as_str()),
+    )
+    .await;
+    assert_eq!(profile_body["wrapped_profile_dek"], "owner-dek-v1");
+
+    common::drop_test_db(&db_name).await;
+}
+
+#[tokio::test]
+async fn rekey_with_empty_envelopes_revokes_all_recipients() {
+    // Keeping nobody = hard-revoke everyone (e.g. suspected compromise).
+    let (app, db_name) = require_app!(common::app_for_test().await);
+    let owner_body = register_full(&app, &unique_email()).await;
+    let owner_token = token(&owner_body);
+    let profile_id = self_profile_id(&owner_body);
+
+    let recipient_b = unique_email();
+    register_full(&app, &recipient_b).await;
+    share_to(&app, &owner_token, &profile_id, &recipient_b).await;
+
+    let (status, body) = common::send_json(
+        &app,
+        "POST",
+        &format!("/api/profiles/{profile_id}/rekey"),
+        Some(json!({
+            "new_wrapped_profile_dek": "owner-dek-v2",
+            "new_wrapped_profile_dek_iv": "owner-dek-iv-v2",
+            "recipient_envelopes": [],
+        })),
+        Some(&owner_token),
+    )
+    .await;
+    assert_eq!(
+        status, 200,
+        "rekey with no envelopes should succeed: {body}"
+    );
+    assert_eq!(
+        body["retained_recipient_user_ids"]
+            .as_array()
+            .unwrap()
+            .len(),
+        0
+    );
+
+    // The shares listing is now empty.
+    let (_, listing) = common::send_json(
+        &app,
+        "GET",
+        &format!("/api/profiles/{profile_id}/shares"),
+        None,
+        Some(&owner_token),
+    )
+    .await;
+    assert_eq!(listing.as_array().unwrap().len(), 0);
+
+    common::drop_test_db(&db_name).await;
+}

web/normogen-web/src/components/profile/ProfileSharing.tsx

@@ -15,6 +15,7 @@ import {
 } from '@mui/material';
 import PersonAddIcon from '@mui/icons-material/PersonAdd';
 import PersonRemoveIcon from '@mui/icons-material/PersonRemove';
+import KeyIcon from '@mui/icons-material/Key';
 import { useProfileStore } from '../../store/useStore';
 
 /** Owner-side sharing UI for a single owned profile: lists the recipients the
@@ -27,6 +28,7 @@ export const ProfileSharing: FC<{ profileId: string }> = ({ profileId }) => {
     loadProfileShares,
     shareProfile,
     revokeShare,
+    rekeyProfile,
     error,
     clearError,
   } = useProfileStore();
@@ -66,6 +68,36 @@ export const ProfileSharing: FC<{ profileId: string }> = ({ profileId }) => {
     }
   };
 
+  const handleHardRevoke = async () => {
+    // Hard revoke = rotate the profile DEK. All currently-listed recipients
+    // are KEPT (re-wrapped to the new DEK); the owner removes specific
+    // recipients via the per-row revoke button above first if they want them
+    // gone at the key level. Expensive (re-encrypts all the profile's data),
+    // but resume-safe — partial runs can be retried.
+    const ok = confirm(
+      'Rotate this profile\'s encryption key?\n\n' +
+        'This re-encrypts ALL the profile\'s data (medications, appointments, ' +
+        'health stats) under a new key — it may take a moment. All currently-' +
+        'listed recipients keep access (re-wrapped to the new key). Anyone who ' +
+        'previously had access and was removed, or any cached copy of the old ' +
+        'key, will stop working.\n\nUse this if you suspect a key was compromised.',
+    );
+    if (!ok) return;
+    setBusy(true);
+    setLocalError('');
+    try {
+      const keepIds = shares.map((s) => s.recipient_user_id);
+      await rekeyProfile(profileId, keepIds);
+    } catch (e: any) {
+      setLocalError(
+        (e?.message || 'Re-key failed') +
+          ' — you can retry; rows already re-encrypted are skipped.',
+      );
+    } finally {
+      setBusy(false);
+    }
+  };
+
   return (
     <Box>
       <Typography variant="subtitle1" sx={{ mb: 1 }}>
@@ -133,6 +165,23 @@ export const ProfileSharing: FC<{ profileId: string }> = ({ profileId }) => {
       <Typography variant="caption" color="text.secondary" sx={{ mt: 1, display: 'block' }}>
         The recipient must have a Normogen account. They'll see this profile in their switcher.
       </Typography>
+
+      <Box sx={{ mt: 3, pt: 2, borderTop: 1, borderColor: 'divider' }}>
+        <Button
+          size="small"
+          color="warning"
+          variant="outlined"
+          startIcon={<KeyIcon />}
+          disabled={busy}
+          onClick={handleHardRevoke}
+        >
+          {busy ? <CircularProgress size={20} /> : 'Rotate encryption key (hard revoke)'}
+        </Button>
+        <Typography variant="caption" color="text.secondary" sx={{ display: 'block', mt: 1 }}>
+          Generates a new key and re-encrypts this profile's data. Use if a key
+          may have been compromised. Resume-safe — you can retry on failure.
+        </Typography>
+      </Box>
     </Box>
   );
 };

web/normogen-web/src/services/api.ts

@@ -24,6 +24,8 @@ import {
   CreateProfileShareRequest,
   ProfileShareListing,
   PublicKeyResponse,
+  RekeyRequest,
+  RekeyResponse,
   HealthStatWireResponse,
   UpdateHealthStatRequest,
   EncryptedFieldWire,
@@ -308,6 +310,18 @@ class ApiService {
     await this.client.delete(`/profiles/${profileId}/shares/${recipientUserId}`);
   }
 
+  /** Owner: hard revoke / rotate the profile DEK (Phase C). The client has
+   *  already re-encrypted the data under a new DEK (client-side) and wrapped
+   *  it to the owner account DEK + each kept recipient. Recipients omitted
+   *  from `recipient_envelopes` are hard-revoked. */
+  async rekeyProfile(profileId: string, req: RekeyRequest): Promise<RekeyResponse> {
+    const response = await this.client.post<RekeyResponse>(
+      `/profiles/${profileId}/rekey`,
+      req,
+    );
+    return response.data;
+  }
+
   // ---- Medications (zero-knowledge: opaque encrypted blobs) ----
 
   async getMedications(profileId?: string): Promise<MedicationWireResponse[]> {

web/normogen-web/src/store/useStore.ts

@@ -41,6 +41,9 @@ import {
   AdherenceStats,
   Profile,
   ProfileShareListing,
+  MedicationWireResponse,
+  AppointmentWireResponse,
+  HealthStatWireResponse,
   Appointment,
   CreateAppointmentRequest,
   UpdateAppointmentRequest,
@@ -153,6 +156,14 @@ interface ProfileState {
   /** Shares the current user has created for a profile (for the owner UI). */
   profileShares: Record<string, ProfileShareListing[]>;
   loadProfileShares: (profileId: string) => Promise<void>;
+  /** Owner: hard revoke / rotate the profile DEK. Re-encrypts all the
+   *  profile's data under a fresh DEK (client-side), then commits the
+   *  rotation server-side. Recipients not in `keepRecipientUserIds` are
+   *  hard-revoked (lose access at the key level). Expensive: O(data size). */
+  rekeyProfile: (
+    profileId: string,
+    keepRecipientUserIds: string[],
+  ) => Promise<void>;
   clearError: () => void;
 }
 
@@ -1121,6 +1132,127 @@ export const useProfileStore = create<ProfileState>()(
       }
     },
 
+    rekeyProfile: async (profileId, keepRecipientUserIds) => {
+      // Phase C hard revoke. Re-encrypts all the profile's data client-side
+      // under a fresh DEK, then commits the rotation. Resume-safe per-row:
+      // if a row was already re-encrypted on a prior partial run, decrypt-
+      // with-old fails and we try decrypt-with-new; if that succeeds, the
+      // row is already on the new DEK and we skip it.
+      const accountDek = getEncKey();
+      const oldDek = getProfileDek(profileId);
+      const myIdentityPrivate = getIdentityPrivate();
+      if (!accountDek || !oldDek) {
+        set({ error: 'Unlock the profile first (no account/profile key)' });
+        throw new Error('No keys');
+      }
+      set({ isLoading: true, error: null });
+      try {
+        const newDek = await generateProfileDek();
+
+        // 3a. Re-encrypt every data row under the new DEK.
+        //   medications + appointments: POST /:id with the new blob.
+        //   health-stats: PUT /:id with the new blob.
+        const reencryptRow = async (
+          getBlob: () => Promise<{ data: string; iv: string } | null>,
+          reencrypt: (newBlob: { data: string; iv: string }) => Promise<void>,
+        ) => {
+          const blob = await getBlob();
+          if (!blob) return;
+          let plaintext: string;
+          try {
+            plaintext = await decryptRaw(blob, oldDek);
+          } catch {
+            // Maybe already re-encrypted on a prior partial run — verify with
+            // the new DEK, and skip if so.
+            try {
+              await decryptRaw(blob, newDek);
+              return; // already on newDek
+            } catch {
+              throw new Error('row could not be decrypted with old or new DEK');
+            }
+          }
+          const newBlob = await encryptRaw(plaintext, newDek);
+          await reencrypt(newBlob);
+        };
+
+        const meds: MedicationWireResponse[] = await apiService.getMedications(profileId);
+        for (const m of meds) {
+          await reencryptRow(
+            async () => (m.encrypted_data?.data ? m.encrypted_data : null),
+            async (newBlob) => {
+              await apiService.updateMedication(m.medication_id, {
+                encrypted_data: newBlob,
+              });
+            },
+          );
+        }
+        const appts: AppointmentWireResponse[] = await apiService.getAppointments(
+          undefined,
+          profileId,
+        );
+        for (const a of appts) {
+          await reencryptRow(
+            async () => (a.encrypted_data?.data ? a.encrypted_data : null),
+            async (newBlob) => {
+              await apiService.updateAppointment(a.appointment_id, { encrypted_data: newBlob });
+            },
+          );
+        }
+        const stats: HealthStatWireResponse[] = await apiService.getHealthStats(profileId);
+        for (const s of stats) {
+          await reencryptRow(
+            async () => (s.encrypted_data?.data ? s.encrypted_data : null),
+            async (newBlob) => {
+              await apiService.updateHealthStat(s.id, { encrypted_data: newBlob });
+            },
+          );
+        }
+
+        // 3b. Build a fresh ECDH envelope per kept recipient.
+        const recipientEnvelopes = [];
+        if (myIdentityPrivate) {
+          const shares = get().profileShares[profileId] ?? [];
+          for (const s of shares) {
+            if (!keepRecipientUserIds.includes(s.recipient_user_id)) continue;
+            const { identity_public_key: recipientPub } = await apiService.getUserPublicKey(
+              s.recipient_email,
+            );
+            const env = await wrapProfileDekToRecipient(
+              newDek,
+              recipientPub,
+              myIdentityPrivate,
+            );
+            recipientEnvelopes.push({
+              recipient_user_id: s.recipient_user_id,
+              ephemeral_public_key: env.ephemeralPublicKey,
+              wrapped_profile_dek: env.wrappedProfileDek.data,
+              wrapped_profile_dek_iv: env.wrappedProfileDek.iv,
+            });
+          }
+        }
+
+        // 3c. Commit: rotate the owner share (new DEK wrapped under the account
+        //     DEK) + recipient envelopes, hard-delete omitted recipients.
+        const ownerWrap = await wrapProfileDek(newDek, accountDek);
+        await apiService.rekeyProfile(profileId, {
+          new_wrapped_profile_dek: ownerWrap.data,
+          new_wrapped_profile_dek_iv: ownerWrap.iv,
+          recipient_envelopes: recipientEnvelopes,
+        });
+
+        // 3d. Swap the in-memory DEK and refresh the share listing.
+        setProfileDek(profileId, newDek);
+        await get().loadProfileShares(profileId);
+        set({ isLoading: false });
+      } catch (error: any) {
+        set({
+          error: error.message || 'Re-key failed (you can retry — already-re-encrypted rows are skipped)',
+          isLoading: false,
+        });
+        throw error;
+      }
+    },
+
     clearError: () => set({ error: null }),
   })),
 );

web/normogen-web/src/types/api.ts

@@ -408,6 +408,29 @@ export interface ProfileShareListing {
   active: boolean;
 }
 
+// Phase C hard revoke: one fresh ECDH envelope per recipient the owner keeps.
+export interface RecipientEnvelope {
+  recipient_user_id: string;
+  ephemeral_public_key: string;
+  wrapped_profile_dek: string;
+  wrapped_profile_dek_iv: string;
+}
+
+// Request body for POST /profiles/:id/rekey (hard revoke / rotate the DEK).
+export interface RekeyRequest {
+  new_wrapped_profile_dek: string;
+  new_wrapped_profile_dek_iv: string;
+  recipient_envelopes: RecipientEnvelope[];
+}
+
+// Response from POST /profiles/:id/rekey.
+export interface RekeyResponse {
+  profile_id: string;
+  wrapped_profile_dek: string;
+  wrapped_profile_dek_iv: string;
+  retained_recipient_user_ids: string[];
+}
+
 // Response from GET /users/public-key?email=...
 export interface PublicKeyResponse {
   user_id: string;