diff --git a/AGENTS.md b/AGENTS.md
index f9e4289..e8bb264 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -17,7 +17,8 @@
 - I2 is not blanket anti-centralization: shared coordination (identity, admission, contract) is centralized in the MA because common state is cheaper held once; decisions that consume local information (matching, relevance, sharing, retention) stay local. Off-wire conduct (link handling, retention, gating) is contract, not conformance.
 
 ## Implementation notes
-- Draft 0.5 specifies JCS (RFC 8785) envelope signing over `{type, from, key, ts, nonce, body}` with `from` = MA-hosted identifier and `key` = pubkey. The code still signs the provisional `FRX/0.4` scheme (`src/crypto.rs`) until Phase B lands — never present current code as interoperable.
+- Wire format matches Draft 0.5: envelope `{type, from, key, ts, nonce, body, sig}` with `from` = identifier, `key` = pubkey; signatures cover the JCS canonical form of the unsigned envelope under prefix `FRX/0.5` (`src/crypto.rs`). Our `canonical_json` is JCS-compatible only for the restricted schema (ASCII keys, integers, no floats) — golden vectors in `tests/conformance.rs` pin the bytes and signature; revisit before claiming interop with non-Rust stacks.
+- Relay addresses transport mailboxes by `key` (unicast `to` = recipient pubkey; queues keyed by pubkey); the identifier is protocol identity only. Registry binding checks `map[key].id == from`.
 - Built: envelope/query/response, Tantivy index, aggregates, member directory. Not built: dashboard UI, directory watching, TLS, lineage/delegation. Responses travel relay-mediated unicast; transport is HTTP long-poll, not SSE.
 - Economics is out of protocol scope (I4: aggregates advise, contracts govern): no receipt, citation, pricing, or settlement fields or message types exist or may be added.
 - Relay verifies signatures and ±300s timestamp skew, carries only `query` broadcasts, holds no history (queue drained on poll), and returns 429 + Retry-After under backpressure — never silent drops. Mailbox polls require proof of key possession: `GET /v1/challenge` then a signed single-use nonce, so knowing a pubkey is not enough to drain its queue.
@@ -45,4 +46,4 @@
 - frxd modes (one binary, config toggles, no code required of publishers): querier (broadcast/local-first search), responder (match incoming queries against shared collections, sign), local index (watch dirs, extract text, explicit shared marking per I9). Use RFC terms querier/responder, not "subscriber/publisher".
 - Roles are not exclusive: a single node may issue queries and answer them concurrently (I5, §3 "any member"). Implement querier/responder as independent enable flags — never an exclusive mode enum or fixed deployment role.
 - Matching accuracy is a project-health concern: start lexical (Tantivy), plan a hybrid cheap lexical gate + optional local embedding rerank (two-stage ingestion, Appendix A); embedding model stays local and replaceable (I2/I5).
-- Identity/registry (RFC Draft 0.5 §4/§6): MA-hosted FQDN identifiers first (`<label>.frx.<ma-domain>`, no DNS needed by users), signed versioned registry snapshot with the MA key pinned; envelope `from` = identifier, `key` = pubkey; registry outage fails static. Member-hosted identities, MA anchor rollover, and unicast confidentiality are §10 open. Implementation phases: A = signed registry snapshot with the current wire format (built and tested, no wire change); B = identifier + `key` + JCS on the wire. Prioritize frictionless onboarding (users may be department-level and cannot create DNS).
+- Identity/registry (RFC Draft 0.5 §4/§6): MA-hosted FQDN identifiers first (`<label>.frx.<ma-domain>`, no DNS needed by users), signed versioned registry snapshot with the MA key pinned; envelope `from` = identifier, `key` = pubkey; registry outage fails static. Member-hosted identities, MA anchor rollover, and unicast confidentiality are §10 open. Implementation phases: A (signed registry snapshot) and B (identifier + `key` + JCS on the wire) are built and tested. Prioritize frictionless onboarding (users may be department-level and cannot create DNS).
diff --git a/src/crypto.rs b/src/crypto.rs
index 0dd4447..fbf2693 100644
--- a/src/crypto.rs
+++ b/src/crypto.rs
@@ -121,20 +121,19 @@ pub fn verify_signature(public_hex: &str, message: &[u8], sig_hex: &str) -> Resu
 }
 
 pub fn signing_bytes(envelope: &Envelope) -> Vec<u8> {
-    format!(
-        "{}\n{}\n{}\n{}\n{}\n{}",
-        PROTOCOL,
-        envelope.msg_type,
-        envelope.from,
-        envelope.ts,
-        envelope.nonce,
-        canonical_json(&envelope.body)
-    )
-    .into_bytes()
+    let unsigned = serde_json::json!({
+        "type": envelope.msg_type,
+        "from": envelope.from,
+        "key": envelope.key,
+        "ts": envelope.ts,
+        "nonce": envelope.nonce,
+        "body": envelope.body,
+    });
+    format!("{}\n{}", PROTOCOL, canonical_json(&unsigned)).into_bytes()
 }
 
 pub fn verify_envelope(envelope: &Envelope) -> Result<()> {
-    verify_signature(&envelope.from, &signing_bytes(envelope), &envelope.sig)
+    verify_signature(&envelope.key, &signing_bytes(envelope), &envelope.sig)
 }
 
 pub fn now_ts() -> u64 {
@@ -160,14 +159,24 @@ mod tests {
     #[test]
     fn envelope_sign_verify_roundtrip() {
         let key = Keypair::generate();
-        let env = Envelope::new(&key, crate::message::TYPE_QUERY, json!({"text": "hello"}));
+        let env = Envelope::new(
+            &key,
+            "alice.example",
+            crate::message::TYPE_QUERY,
+            json!({"text": "hello"}),
+        );
         verify_envelope(&env).unwrap();
     }
 
     #[test]
     fn tampered_body_fails_verification() {
         let key = Keypair::generate();
-        let mut env = Envelope::new(&key, crate::message::TYPE_QUERY, json!({"text": "hello"}));
+        let mut env = Envelope::new(
+            &key,
+            "alice.example",
+            crate::message::TYPE_QUERY,
+            json!({"text": "hello"}),
+        );
         env.body = json!({"text": "hello", "extra": true});
         assert!(verify_envelope(&env).is_err());
     }
diff --git a/src/lib.rs b/src/lib.rs
index 1d57826..43ce497 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -10,4 +10,4 @@ pub mod relay;
 pub mod render;
 
 pub const VERSION: &str = env!("CARGO_PKG_VERSION");
-pub const PROTOCOL: &str = "FRX/0.4";
+pub const PROTOCOL: &str = "FRX/0.5";
diff --git a/src/message.rs b/src/message.rs
index 11de106..26939f1 100644
--- a/src/message.rs
+++ b/src/message.rs
@@ -22,6 +22,7 @@ pub struct Envelope {
     #[serde(rename = "type")]
     pub msg_type: String,
     pub from: String,
+    pub key: String,
     pub ts: u64,
     pub nonce: String,
     pub body: Value,
@@ -29,10 +30,11 @@ pub struct Envelope {
 }
 
 impl Envelope {
-    pub fn new(key: &Keypair, msg_type: &str, body: Value) -> Self {
+    pub fn new(key: &Keypair, identifier: &str, msg_type: &str, body: Value) -> Self {
         let mut envelope = Self {
             msg_type: msg_type.to_string(),
-            from: key.public_hex(),
+            from: identifier.to_string(),
+            key: key.public_hex(),
             ts: now_ts(),
             nonce: random_nonce(),
             body,
@@ -183,7 +185,7 @@ mod tests {
     #[test]
     fn envelope_rejects_wrong_type() {
         let key = Keypair::generate();
-        let envelope = Envelope::new(&key, TYPE_RESPONSE, json!({}));
+        let envelope = Envelope::new(&key, "bob.example", TYPE_RESPONSE, json!({}));
         assert!(require_type(&envelope, TYPE_QUERY).is_err());
     }
 }
diff --git a/src/node.rs b/src/node.rs
index 93781fc..f048327 100644
--- a/src/node.rs
+++ b/src/node.rs
@@ -284,6 +284,14 @@ impl Node {
         self.index.doc_count()
     }
 
+    pub fn identifier(&self) -> String {
+        self.config
+            .node
+            .id
+            .clone()
+            .unwrap_or_else(|| self.key.public_hex())
+    }
+
     pub fn sent(&self) -> u64 {
         self.sent.load(Ordering::SeqCst)
     }
@@ -359,7 +367,12 @@ impl Node {
                 let mut aggregates = self.aggregates.lock().expect("aggregates lock");
                 *aggregates.sent.entry(current_period()).or_default() += 1;
             }
-            let envelope = Envelope::new(&self.key, TYPE_QUERY, serde_json::to_value(&query)?);
+            let envelope = Envelope::new(
+                &self.key,
+                &self.identifier(),
+                TYPE_QUERY,
+                serde_json::to_value(&query)?,
+            );
             self.publish(&envelope).await;
             let timeout = Duration::from_millis(timeout_ms.unwrap_or(self.config.query.timeout_ms));
             let deadline = Instant::now() + timeout;
@@ -450,19 +463,19 @@ impl Node {
                 .as_ref()
                 .map(|signed| authorized_keys(signed, now_ts()));
             match authorized {
-                Some(map) => {
-                    let entry = map.get(&envelope.from);
-                    (entry.map(|(_, class)| class.clone()), entry.is_some())
-                }
+                Some(map) => match map.get(&envelope.key) {
+                    Some((id, class)) if id == &envelope.from => (Some(class.clone()), true),
+                    _ => (None, false),
+                },
                 None => (None, false),
             }
         } else {
             let members = self.members.read().expect("members lock");
-            let class = self.member_class(&members, &envelope.from);
+            let class = self.member_class(&members, &envelope.key);
             let listed = if members.is_empty() {
                 self.config.node.dev_bootstrap
             } else {
-                class.is_some()
+                class.is_some() && envelope.from == envelope.key
             };
             (class, listed)
         };
@@ -471,7 +484,7 @@ impl Node {
         }
         match envelope.msg_type.as_str() {
             TYPE_QUERY => {
-                if envelope.from == self.key.public_hex() || !self.config.node.responder {
+                if envelope.from == self.identifier() || !self.config.node.responder {
                     return;
                 }
                 let Ok(query) = envelope.parse_body::<QueryBody>() else {
@@ -491,7 +504,7 @@ impl Node {
                 }
                 let node = self.clone();
                 let relay = relay.to_string();
-                let querier = envelope.from.clone();
+                let querier = envelope.key.clone();
                 tokio::spawn(async move {
                     if let Err(error) = node.respond(&query, &querier, &relay).await {
                         eprintln!("responder failed: {error}");
@@ -535,10 +548,12 @@ impl Node {
                 }
                 let node = self.clone();
                 let period = period.to_string();
-                let requester = envelope.from.clone();
+                let requester_id = envelope.from.clone();
+                let requester_key = envelope.key.clone();
                 let relay = relay.to_string();
                 tokio::spawn(async move {
-                    node.serve_aggregate(&period, &requester, &relay).await;
+                    node.serve_aggregate(&period, &requester_id, &requester_key, &relay)
+                        .await;
                 });
             }
             _ => {}
@@ -552,7 +567,12 @@ impl Node {
             return Ok(());
         }
         let body = build_response(&query.qid, response_items(&hits), total, max);
-        let envelope = Envelope::new(&self.key, TYPE_RESPONSE, serde_json::to_value(&body)?);
+        let envelope = Envelope::new(
+            &self.key,
+            &self.identifier(),
+            TYPE_RESPONSE,
+            serde_json::to_value(&body)?,
+        );
         self.send_unicast(querier, envelope, relay).await
     }
 
@@ -572,7 +592,12 @@ impl Node {
             .first()
             .ok_or_else(|| anyhow!("no relays configured"))?
             .clone();
-        let envelope = Envelope::new(&self.key, TYPE_AGGREGATE, json!({ "period": period }));
+        let envelope = Envelope::new(
+            &self.key,
+            &self.identifier(),
+            TYPE_AGGREGATE,
+            json!({ "period": period }),
+        );
         self.send_unicast(to, envelope, &relay).await?;
         let key = (to.to_string(), period.to_string());
         let deadline = Instant::now()
@@ -594,13 +619,19 @@ impl Node {
         }
     }
 
-    async fn serve_aggregate(&self, period: &str, requester: &str, relay: &str) {
-        let body = self.aggregate_for(period, Some(requester));
+    async fn serve_aggregate(
+        &self,
+        period: &str,
+        requester_id: &str,
+        requester_key: &str,
+        relay: &str,
+    ) {
+        let body = self.aggregate_for(period, Some(requester_id));
         let Ok(value) = serde_json::to_value(&body) else {
             return;
         };
-        let envelope = Envelope::new(&self.key, TYPE_AGGREGATE, value);
-        if let Err(error) = self.send_unicast(requester, envelope, relay).await {
+        let envelope = Envelope::new(&self.key, &self.identifier(), TYPE_AGGREGATE, value);
+        if let Err(error) = self.send_unicast(requester_key, envelope, relay).await {
             eprintln!("aggregate reply failed: {error}");
         }
     }
diff --git a/src/relay.rs b/src/relay.rs
index d3472e0..f18d298 100644
--- a/src/relay.rs
+++ b/src/relay.rs
@@ -72,7 +72,7 @@ impl Relay {
                 Ok(1)
             }
             None => {
-                let from = envelope.from.clone();
+                let from = envelope.key.clone();
                 inner.members.entry(from).or_default();
                 let mut delivered = 0;
                 for queue in inner.members.values_mut() {
diff --git a/tests/common/mod.rs b/tests/common/mod.rs
index 604e151..e883995 100644
--- a/tests/common/mod.rs
+++ b/tests/common/mod.rs
@@ -59,9 +59,18 @@ pub fn free_port() -> u16 {
     listener.local_addr().unwrap().port()
 }
 
-pub fn query_envelope(key: &Keypair, text: &str, max_results: usize) -> Envelope {
+pub fn query_envelope(key: &Keypair, identifier: &str, text: &str, max_results: usize) -> Envelope {
     let body = QueryBody::new(text, max_results);
-    Envelope::new(key, TYPE_QUERY, serde_json::to_value(&body).unwrap())
+    Envelope::new(
+        key,
+        identifier,
+        TYPE_QUERY,
+        serde_json::to_value(&body).unwrap(),
+    )
+}
+
+pub fn test_envelope(key: &Keypair, msg_type: &str, body: Value) -> Envelope {
+    Envelope::new(key, &key.public_hex(), msg_type, body)
 }
 
 pub async fn challenge(client: &reqwest::Client, relay_url: &str, member: &str) -> Option<String> {
diff --git a/tests/concurrency.rs b/tests/concurrency.rs
index bbd7d76..98d13bc 100644
--- a/tests/concurrency.rs
+++ b/tests/concurrency.rs
@@ -103,7 +103,7 @@ async fn multi_relay_deduplicates_and_responds_once() {
     let alice = Keypair::generate();
     register(&http, &relay_one, &alice).await;
     register(&http, &relay_two, &alice).await;
-    let envelope = query_envelope(&alice, "rust", 5);
+    let envelope = query_envelope(&alice, &alice.public_hex(), "rust", 5);
     assert!(
         publish(&http, &relay_one, &envelope)
             .await
@@ -192,7 +192,7 @@ async fn poll_returns_queued_batch_in_one_call() {
     let member = Keypair::generate();
     register(&http, &relay_url, &member).await;
     for index in 0..3 {
-        let envelope = query_envelope(&member, &format!("query {index}"), 5);
+        let envelope = query_envelope(&member, &member.public_hex(), &format!("query {index}"), 5);
         assert!(
             publish(&http, &relay_url, &envelope)
                 .await
diff --git a/tests/conformance.rs b/tests/conformance.rs
index 0599479..c108203 100644
--- a/tests/conformance.rs
+++ b/tests/conformance.rs
@@ -7,7 +7,7 @@ use std::time::{Duration, Instant};
 
 use common::{
     ask, challenge, client, collection, config_for, messages_of_type, poll, poll_messages, publish,
-    query_envelope, register, spawn_relay, spawn_relay_with_capacity, unicast,
+    query_envelope, register, spawn_relay, spawn_relay_with_capacity, test_envelope, unicast,
 };
 use frxd::crypto::Keypair;
 use frxd::index::LocalIndex;
@@ -87,7 +87,7 @@ async fn raw_query(
     timeout_ms: u64,
 ) -> Vec<Value> {
     register(http, relay_url, asker).await;
-    let envelope = query_envelope(asker, text, 5);
+    let envelope = query_envelope(asker, &asker.public_hex(), text, 5);
     assert!(
         publish(http, relay_url, &envelope)
             .await
@@ -100,13 +100,14 @@ async fn raw_query(
 #[test]
 fn envelope_field_set_is_fixed() {
     let key = Keypair::generate();
-    let envelope = Envelope::new(&key, TYPE_QUERY, json!({"qid": "q", "text": "t"}));
+    let envelope = test_envelope(&key, TYPE_QUERY, json!({"qid": "q", "text": "t"}));
     let value = serde_json::to_value(&envelope).unwrap();
     assert_eq!(
         keys(&value),
         BTreeSet::from([
             "body".to_string(),
             "from".to_string(),
+            "key".to_string(),
             "nonce".to_string(),
             "sig".to_string(),
             "ts".to_string(),
@@ -337,7 +338,7 @@ async fn entities_are_optional_hints() {
         "entities": ["Q999999", "not-a-real-entity"],
         "budget": {"max_results": 5}
     });
-    let envelope = Envelope::new(&alice, TYPE_QUERY, body);
+    let envelope = test_envelope(&alice, TYPE_QUERY, body);
     assert!(
         publish(&http, &relay_url, &envelope)
             .await
@@ -384,7 +385,7 @@ async fn member_directory_filters_senders() {
     assert_eq!(trusted.len(), 1, "trusted member got no response");
 
     register(&http, &relay_url, &untrusted).await;
-    let envelope = query_envelope(&untrusted, "rust", 5);
+    let envelope = query_envelope(&untrusted, &untrusted.public_hex(), "rust", 5);
     assert!(
         publish(&http, &relay_url, &envelope)
             .await
@@ -424,7 +425,7 @@ async fn rotated_keys_are_accepted_through_previous_listing() {
 
     let http = client();
     register(&http, &relay_url, &old_key).await;
-    let envelope = query_envelope(&old_key, "rust", 5);
+    let envelope = query_envelope(&old_key, &old_key.public_hex(), "rust", 5);
     assert!(
         publish(&http, &relay_url, &envelope)
             .await
@@ -436,7 +437,7 @@ async fn rotated_keys_are_accepted_through_previous_listing() {
 
     tokio::time::sleep(Duration::from_millis(20)).await;
     frxd::config::save_members(&config.members_path(), &listing(Vec::new())).unwrap();
-    let envelope = query_envelope(&old_key, "rust", 5);
+    let envelope = query_envelope(&old_key, &old_key.public_hex(), "rust", 5);
     assert!(
         publish(&http, &relay_url, &envelope)
             .await
@@ -453,7 +454,7 @@ async fn stale_envelopes_are_rejected() {
     let http = client();
     let key = Keypair::generate();
 
-    let mut envelope = query_envelope(&key, "stale", 5);
+    let mut envelope = query_envelope(&key, &key.public_hex(), "stale", 5);
     envelope.ts = frxd::crypto::now_ts().saturating_sub(3600);
     envelope.sig = key.sign(&frxd::crypto::signing_bytes(&envelope));
     assert_eq!(
@@ -461,7 +462,7 @@ async fn stale_envelopes_are_rejected() {
         reqwest::StatusCode::BAD_REQUEST
     );
 
-    let mut response = Envelope::new(
+    let mut response = test_envelope(
         &key,
         TYPE_RESPONSE,
         json!({"qid": "q1", "results": [], "truncated": false, "more_available": 0, "cursor": null}),
@@ -484,12 +485,12 @@ async fn backpressure_is_visible_and_recoverable() {
     let publisher = Keypair::generate();
     register(&http, &relay_url, &member).await;
 
-    let first = query_envelope(&publisher, "one", 5);
+    let first = query_envelope(&publisher, &publisher.public_hex(), "one", 5);
     assert_eq!(
         publish(&http, &relay_url, &first).await.status(),
         reqwest::StatusCode::ACCEPTED
     );
-    let second = query_envelope(&publisher, "two", 5);
+    let second = query_envelope(&publisher, &publisher.public_hex(), "two", 5);
     let response = publish(&http, &relay_url, &second).await;
     assert_eq!(response.status(), reqwest::StatusCode::TOO_MANY_REQUESTS);
     assert_eq!(
@@ -511,7 +512,7 @@ async fn backpressure_is_visible_and_recoverable() {
         1
     );
 
-    let third = query_envelope(&publisher, "three", 5);
+    let third = query_envelope(&publisher, &publisher.public_hex(), "three", 5);
     assert_eq!(
         publish(&http, &relay_url, &third).await.status(),
         reqwest::StatusCode::ACCEPTED
@@ -527,7 +528,7 @@ async fn unicast_is_need_to_know() {
     register(&http, &relay_url, &alice).await;
     register(&http, &relay_url, &bob).await;
 
-    let query = query_envelope(&alice, "rust", 5);
+    let query = query_envelope(&alice, &alice.public_hex(), "rust", 5);
     assert!(
         publish(&http, &relay_url, &query)
             .await
@@ -535,7 +536,7 @@ async fn unicast_is_need_to_know() {
             .is_success()
     );
 
-    let response = Envelope::new(
+    let response = test_envelope(
         &bob,
         TYPE_RESPONSE,
         json!({"qid": "q1", "results": [], "truncated": false, "more_available": 0, "cursor": null}),
@@ -561,7 +562,7 @@ async fn unicast_to_unknown_member_is_visible() {
     let relay_url = spawn_relay().await;
     let http = client();
     let sender = Keypair::generate();
-    let response = Envelope::new(
+    let response = test_envelope(
         &sender,
         TYPE_RESPONSE,
         json!({"qid": "q1", "results": [], "truncated": false, "more_available": 0, "cursor": null}),
@@ -580,12 +581,12 @@ async fn tampered_envelopes_are_rejected() {
     let relay_url = spawn_relay().await;
     let http = client();
     let key = Keypair::generate();
-    let mut envelope = query_envelope(&key, "rust", 5);
+    let mut envelope = query_envelope(&key, &key.public_hex(), "rust", 5);
     envelope.body = json!({"qid": "q1", "text": "forged", "budget": {"max_results": 5}});
     let publish_response = publish(&http, &relay_url, &envelope).await;
     assert_eq!(publish_response.status(), reqwest::StatusCode::BAD_REQUEST);
 
-    let mut response = Envelope::new(
+    let mut response = test_envelope(
         &key,
         TYPE_RESPONSE,
         json!({"qid": "q1", "results": [], "truncated": false, "more_available": 0, "cursor": null}),
@@ -854,7 +855,7 @@ async fn aggregates_are_unicast_only_and_ignored_by_nodes() {
     let sender = Keypair::generate();
     register(&http, &relay_url, &bob.node.key).await;
 
-    let broadcast = Envelope::new(
+    let broadcast = test_envelope(
         &sender,
         TYPE_AGGREGATE,
         json!({"period": "2026-03", "sent": 1, "passed": 0}),
@@ -865,7 +866,7 @@ async fn aggregates_are_unicast_only_and_ignored_by_nodes() {
         "aggregates must not travel the broadcast channel"
     );
 
-    let unicast_envelope = Envelope::new(
+    let unicast_envelope = test_envelope(
         &sender,
         TYPE_AGGREGATE,
         json!({"period": "2026-03", "sent": 1, "passed": 0}),
@@ -927,7 +928,7 @@ async fn duplicate_delivery_is_answered_once() {
     let alice = Keypair::generate();
     let http = client();
     register(&http, &relay_url, &alice).await;
-    let envelope = query_envelope(&alice, "rust", 5);
+    let envelope = query_envelope(&alice, &alice.public_hex(), "rust", 5);
     assert!(
         publish(&http, &relay_url, &envelope)
             .await
@@ -1000,7 +1001,8 @@ async fn multiple_responders_merge_with_provenance() {
 fn canonical_signing_bytes_are_stable() {
     let mut envelope = Envelope {
         msg_type: TYPE_QUERY.to_string(),
-        from: "aa".repeat(32),
+        from: "alice.frx.example".to_string(),
+        key: "aa".repeat(32),
         ts: 1_700_000_000,
         nonce: "00112233445566778899aabbccddeeff".to_string(),
         body: json!({"text": "rust", "qid": "q1", "budget": {"max_results": 5}, "entities": []}),
@@ -1011,9 +1013,15 @@ fn canonical_signing_bytes_are_stable() {
         json!({"entities": [], "budget": {"max_results": 5}, "qid": "q1", "text": "rust"});
     let second = frxd::crypto::signing_bytes(&envelope);
     assert_eq!(first, second);
+    let key = frxd::crypto::Keypair::from_hex(&"00".repeat(32)).unwrap();
+    let signature = key.sign(&first);
     assert_eq!(
         String::from_utf8(first).unwrap(),
-        "FRX/0.4\nquery\naaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\n1700000000\n00112233445566778899aabbccddeeff\n{\"budget\":{\"max_results\":5},\"entities\":[],\"qid\":\"q1\",\"text\":\"rust\"}"
+        "FRX/0.5\n{\"body\":{\"budget\":{\"max_results\":5},\"entities\":[],\"qid\":\"q1\",\"text\":\"rust\"},\"from\":\"alice.frx.example\",\"key\":\"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa\",\"nonce\":\"00112233445566778899aabbccddeeff\",\"ts\":1700000000,\"type\":\"query\"}"
+    );
+    assert_eq!(
+        signature,
+        "2d5df0f85b5ea6b97d5dbc53d316b410c848d52e407583f9740d10889ba5a40fbcf03a930fa7d351689aa657884e3a32e0c6941ff11653a71d75dea58b3e9b09"
     );
 }
 
@@ -1033,7 +1041,7 @@ async fn query_body_without_entities_parses() {
     let alice = Keypair::generate();
     let http = client();
     register(&http, &relay_url, &alice).await;
-    let envelope = Envelope::new(
+    let envelope = test_envelope(
         &alice,
         TYPE_QUERY,
         json!({"qid": "min", "text": "rust", "budget": {"max_results": 5}}),
diff --git a/tests/phase1.rs b/tests/phase1.rs
index a639b0f..60b2a52 100644
--- a/tests/phase1.rs
+++ b/tests/phase1.rs
@@ -2,9 +2,9 @@ mod common;
 
 use std::fs;
 
-use common::{ask, client, collection, config_for, publish, spawn_relay};
+use common::{ask, client, collection, config_for, publish, spawn_relay, test_envelope};
 use frxd::index::LocalIndex;
-use frxd::message::{EXPOSURE_FULL, Envelope, TYPE_RESPONSE};
+use frxd::message::{EXPOSURE_FULL, TYPE_RESPONSE};
 use frxd::node::Node;
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 4)]
@@ -106,7 +106,7 @@ async fn two_node_broadcast_query_flow() {
 async fn relay_rejects_non_query_broadcasts() {
     let relay_url = spawn_relay().await;
     let key = frxd::crypto::Keypair::generate();
-    let envelope = Envelope::new(
+    let envelope = test_envelope(
         &key,
         TYPE_RESPONSE,
         serde_json::json!({"qid": "x", "results": []}),
diff --git a/tests/purges.rs b/tests/purges.rs
index 7278cfc..9524236 100644
--- a/tests/purges.rs
+++ b/tests/purges.rs
@@ -3,11 +3,11 @@ mod common;
 use std::collections::BTreeSet;
 use std::fs;
 
-use common::{client, collection, config_for, poll, publish, spawn_relay, unicast};
+use common::{client, collection, config_for, poll, publish, spawn_relay, test_envelope, unicast};
 use frxd::crypto::Keypair;
 use frxd::index::LocalIndex;
 use frxd::message::{
-    AggregateBody, Envelope, QueryBody, ResponseItem, TYPE_AGGREGATE, TYPE_QUERY, TYPE_RESPONSE,
+    AggregateBody, QueryBody, ResponseItem, TYPE_AGGREGATE, TYPE_QUERY, TYPE_RESPONSE,
     build_response,
 };
 use frxd::node::{self, Node};
@@ -39,7 +39,7 @@ fn no_bounty_winner_selection_or_slashing() {
     let query = serde_json::to_value(QueryBody::new("rust", 5)).unwrap();
     assert_exact_keys(&query, &["qid", "text", "entities", "budget"]);
     assert_exact_keys(query.get("budget").unwrap(), &["max_results"]);
-    let envelope = Envelope::new(&Keypair::generate(), TYPE_QUERY, query.clone());
+    let envelope = test_envelope(&Keypair::generate(), TYPE_QUERY, query.clone());
     let envelope = serde_json::to_value(&envelope).unwrap();
     for value in [&query, &envelope] {
         assert_absent_fields(
@@ -64,7 +64,7 @@ async fn no_in_protocol_citation_accounting_or_settlement() {
     let key = Keypair::generate();
 
     for msg_type in ["receipt", "settlement", "citation", "invoice"] {
-        let envelope = Envelope::new(&key, msg_type, serde_json::json!({}));
+        let envelope = test_envelope(&key, msg_type, serde_json::json!({}));
         assert_eq!(
             publish(&http, &relay_url, &envelope).await.status(),
             reqwest::StatusCode::BAD_REQUEST,
@@ -126,7 +126,7 @@ async fn no_protocol_query_dedup() {
     let relay_url = spawn_relay().await;
     let http = client();
     let key = Keypair::generate();
-    let envelope = Envelope::new(
+    let envelope = test_envelope(
         &key,
         TYPE_QUERY,
         serde_json::json!({"qid": "q1", "text": "rust"}),
@@ -225,7 +225,7 @@ async fn no_aggregate_appeals() {
     let sender = Keypair::generate();
     let member = Keypair::generate();
 
-    let dispute = Envelope::new(
+    let dispute = test_envelope(
         &sender,
         "dispute",
         serde_json::json!({"about": "counter", "reason": "unfair"}),
@@ -245,7 +245,7 @@ async fn no_aggregate_appeals() {
         poll(&http, &relay_url, &member, 30).await.status(),
         reqwest::StatusCode::NO_CONTENT
     );
-    let aggregate = Envelope::new(
+    let aggregate = test_envelope(
         &sender,
         TYPE_AGGREGATE,
         serde_json::to_value(AggregateBody {
@@ -304,7 +304,7 @@ async fn no_topic_channels() {
         poll(&http, &relay_url, &bob, 30).await.status(),
         reqwest::StatusCode::NO_CONTENT
     );
-    let envelope = Envelope::new(
+    let envelope = test_envelope(
         &alice,
         TYPE_QUERY,
         serde_json::json!({"qid": "q1", "text": "rust"}),
@@ -335,7 +335,7 @@ async fn no_broadcast_responses() {
     let http = client();
     let key = Keypair::generate();
     for msg_type in [TYPE_RESPONSE, "evidence", "commons", "broadcast_response"] {
-        let envelope = Envelope::new(&key, msg_type, serde_json::json!({}));
+        let envelope = test_envelope(&key, msg_type, serde_json::json!({}));
         assert_eq!(
             publish(&http, &relay_url, &envelope).await.status(),
             reqwest::StatusCode::BAD_REQUEST,
@@ -382,7 +382,7 @@ async fn no_supply_announce_firehose() {
     let http = client();
     let key = Keypair::generate();
     for msg_type in ["announce", "supply", "documents", "publish"] {
-        let envelope = Envelope::new(&key, msg_type, serde_json::json!({}));
+        let envelope = test_envelope(&key, msg_type, serde_json::json!({}));
         assert_eq!(
             publish(&http, &relay_url, &envelope).await.status(),
             reqwest::StatusCode::BAD_REQUEST,
@@ -404,7 +404,7 @@ async fn no_durable_replayable_broadcast_stream() {
     let relay_url = spawn_relay().await;
     let http = client();
     let key = Keypair::generate();
-    let envelope = Envelope::new(
+    let envelope = test_envelope(
         &key,
         TYPE_QUERY,
         serde_json::json!({"qid": "q1", "text": "rust"}),
diff --git a/tests/registry.rs b/tests/registry.rs
index e6647bc..631423a 100644
--- a/tests/registry.rs
+++ b/tests/registry.rs
@@ -78,11 +78,12 @@ async fn responses_for(
     http: &reqwest::Client,
     relay_url: &str,
     asker: &Keypair,
+    identifier: &str,
     text: &str,
     timeout_ms: u64,
 ) -> Vec<Value> {
     register(http, relay_url, asker).await;
-    let envelope = query_envelope(asker, text, 5);
+    let envelope = query_envelope(asker, identifier, text, 5);
     assert!(
         publish(http, relay_url, &envelope)
             .await
@@ -133,16 +134,24 @@ async fn registry_gates_membership_and_revocation_propagates() {
     .await;
     let http = client();
 
-    let accepted = responses_for(&http, &relay_url, &alice, "rust", 700).await;
+    let accepted = responses_for(&http, &relay_url, &alice, "alice.frx.example", "rust", 700).await;
     assert_eq!(accepted.len(), 1, "listed member got no response");
 
     let stranger = Keypair::generate();
-    let denied = responses_for(&http, &relay_url, &stranger, "rust", 400).await;
+    let denied = responses_for(
+        &http,
+        &relay_url,
+        &stranger,
+        &stranger.public_hex(),
+        "rust",
+        400,
+    )
+    .await;
     assert!(denied.is_empty(), "unlisted key was answered");
 
     tokio::time::sleep(Duration::from_millis(20)).await;
     registry::save_registry(&registry_path, &ma_registry(&ma, Vec::new(), 2)).unwrap();
-    let revoked = responses_for(&http, &relay_url, &alice, "rust", 500).await;
+    let revoked = responses_for(&http, &relay_url, &alice, "alice.frx.example", "rust", 500).await;
     assert!(revoked.is_empty(), "revoked member still answered");
 
     tokio::time::sleep(Duration::from_millis(20)).await;
@@ -155,7 +164,8 @@ async fn registry_gates_membership_and_revocation_propagates() {
         ),
     )
     .unwrap();
-    let rolled_back = responses_for(&http, &relay_url, &alice, "rust", 500).await;
+    let rolled_back =
+        responses_for(&http, &relay_url, &alice, "alice.frx.example", "rust", 500).await;
     assert!(
         rolled_back.is_empty(),
         "registry rollback re-admitted a revoked member"
@@ -188,7 +198,7 @@ async fn forged_or_wrong_key_snapshot_closes_the_registry() {
     )
     .await;
     let http = client();
-    let denied = responses_for(&http, &relay_url, &alice, "rust", 400).await;
+    let denied = responses_for(&http, &relay_url, &alice, "alice.frx.example", "rust", 400).await;
     assert!(
         denied.is_empty(),
         "snapshot signed by wrong key was trusted"
@@ -226,7 +236,7 @@ async fn expired_key_is_not_authorized() {
     )
     .await;
     let http = client();
-    let denied = responses_for(&http, &relay_url, &alice, "rust", 400).await;
+    let denied = responses_for(&http, &relay_url, &alice, "alice.frx.example", "rust", 400).await;
     assert!(denied.is_empty(), "expired key was answered");
 }
 
@@ -243,7 +253,7 @@ async fn fail_static_uses_last_validated_snapshot() {
     );
 
     let cached_dir = root.path().join("bob-cached");
-    let mut config = config_with_registry(
+    let config = config_with_registry(
         &cached_dir,
         "bob",
         &relay_url,
@@ -264,7 +274,7 @@ async fn fail_static_uses_last_validated_snapshot() {
     let _bob = Node::start(config.clone()).await.unwrap();
 
     let http = client();
-    let accepted = responses_for(&http, &relay_url, &alice, "rust", 700).await;
+    let accepted = responses_for(&http, &relay_url, &alice, "alice.frx.example", "rust", 700).await;
     assert_eq!(
         accepted.len(),
         1,
@@ -287,7 +297,7 @@ async fn fail_static_uses_last_validated_snapshot() {
             .unwrap();
     }
     let _bob2 = Node::start(fresh).await.unwrap();
-    let denied = responses_for(&http, &relay_url, &alice, "rust", 400).await;
+    let denied = responses_for(&http, &relay_url, &alice, "alice.frx.example", "rust", 400).await;
     assert!(
         denied.is_empty(),
         "unreachable registry without cache must close, not open"
@@ -337,7 +347,7 @@ async fn registry_can_be_served_over_http() {
 
     let _bob = bob_with_docs(root.path(), &relay_url, &registry_url, &ma.public_hex()).await;
     let http = client();
-    let accepted = responses_for(&http, &relay_url, &alice, "rust", 900).await;
+    let accepted = responses_for(&http, &relay_url, &alice, "alice.frx.example", "rust", 900).await;
     assert_eq!(
         accepted.len(),
         1,