Infer key log labels from secret kind

src/client/hs.rs

@@ -332,7 +332,6 @@ fn emit_client_hello_for_retry(sess: &mut ClientSessionImpl,
             .get_key_schedule()
             .derive_logged_secret(SecretKind::ClientEarlyTrafficSecret, &client_hello_hash,
                                   &*sess.config.key_log,
-                                  "CLIENT_EARLY_TRAFFIC_SECRET",
                                   &handshake.randoms.client);
         // Set early data encryption key
         sess.common

src/client/tls13.rs

@@ -214,7 +214,6 @@ pub fn start_handshake_traffic(sess: &mut ClientSessionImpl,
             .derive_logged_secret(SecretKind::ClientHandshakeTrafficSecret,
                                   &handshake.hash_at_client_recvd_server_hello,
                                   &*sess.config.key_log,
-                                  "CLIENT_HANDSHAKE_TRAFFIC_SECRET",
                                   &handshake.randoms.client);
         sess.common.set_message_encrypter(cipher::new_tls13_write(suite, &write_key));
         sess.common.get_mut_key_schedule().current_client_traffic_secret = Some(write_key);
@@ -224,7 +223,6 @@ pub fn start_handshake_traffic(sess: &mut ClientSessionImpl,
         .derive_logged_secret(SecretKind::ServerHandshakeTrafficSecret,
                               &handshake.hash_at_client_recvd_server_hello,
                               &*sess.config.key_log,
-                              "SERVER_HANDSHAKE_TRAFFIC_SECRET",
                               &handshake.randoms.client);
     sess.common.set_message_decrypter(cipher::new_tls13_read(suite, &read_key));
     sess.common.get_mut_key_schedule().current_server_traffic_secret = Some(read_key);
@@ -405,7 +403,6 @@ impl hs::State for ExpectEncryptedExtensions {
                         SecretKind::ClientHandshakeTrafficSecret,
                         &self.handshake.hash_at_client_recvd_server_hello,
                         &*sess.config.key_log,
-                        "CLIENT_HANDSHAKE_TRAFFIC_SECRET",
                         &self.handshake.randoms.client);
                 sess.common.set_message_encrypter(cipher::new_tls13_write(suite, &write_key));
                 sess.common.get_mut_key_schedule()
@@ -833,7 +830,6 @@ impl hs::State for ExpectFinished {
                     SecretKind::ClientHandshakeTrafficSecret,
                     &st.handshake.hash_at_client_recvd_server_hello,
                     &*sess.config.key_log,
-                    "CLIENT_HANDSHAKE_TRAFFIC_SECRET",
                     &st.handshake.randoms.client);
             Some(key)
         } else {
@@ -853,7 +849,6 @@ impl hs::State for ExpectFinished {
                 SecretKind::ServerApplicationTrafficSecret,
                 &handshake_hash,
                 &*sess.config.key_log,
-                "SERVER_TRAFFIC_SECRET_0",
                 &st.handshake.randoms.client);
         sess.common.set_message_decrypter(cipher::new_tls13_read(suite, &read_key));
         sess.common
@@ -865,7 +860,6 @@ impl hs::State for ExpectFinished {
             .derive_logged_secret(SecretKind::ExporterMasterSecret,
                                   &handshake_hash,
                                   &*sess.config.key_log,
-                                  "EXPORTER_SECRET",
                                   &st.handshake.randoms.client);
         sess.common
             .get_mut_key_schedule()
@@ -901,7 +895,6 @@ impl hs::State for ExpectFinished {
             .derive_logged_secret(SecretKind::ClientApplicationTrafficSecret,
                                   &handshake_hash,
                                   &*sess.config.key_log,
-                                  "CLIENT_TRAFFIC_SECRET_0",
                                   &st.handshake.randoms.client);
         sess.common.set_message_encrypter(cipher::new_tls13_write(suite, &write_key));
         sess.common

src/key_schedule.rs

@@ -34,6 +34,19 @@ impl SecretKind {
             SecretKind::DerivedSecret => b"derived",
         }
     }
+
+    fn log_label(self) -> Option<&'static str> {
+        use self::SecretKind::*;
+        Some(match self {
+            ClientEarlyTrafficSecret => "CLIENT_EARLY_TRAFFIC_SECRET",
+            ClientHandshakeTrafficSecret => "CLIENT_HANDSHAKE_TRAFFIC_SECRET",
+            ServerHandshakeTrafficSecret => "SERVER_HANDSHAKE_TRAFFIC_SECRET",
+            ClientApplicationTrafficSecret => "CLIENT_TRAFFIC_SECRET_0",
+            ServerApplicationTrafficSecret => "SERVER_TRAFFIC_SECRET_0",
+            ExporterMasterSecret => "EXPORTER_SECRET",
+            _ => { return None; }
+        })
+    }
 }
 
 /// This is the TLS1.3 key schedule.  It stores the current secret,
@@ -91,9 +104,10 @@ impl KeySchedule {
     }
 
     pub fn derive_logged_secret(&self, kind: SecretKind, hs_hash: &[u8],
-                                key_log: &dyn KeyLog, log_label: &str, client_random: &[u8; 32])
+                                key_log: &dyn KeyLog, client_random: &[u8; 32])
         -> hkdf::Prk
     {
+        let log_label = kind.log_label().expect("not a loggable secret");
         if key_log.will_log(log_label) {
             let secret = self.derive::<PayloadU8, _>(PayloadU8Len(self.algorithm.len()), kind, hs_hash)
                 .into_inner();
@@ -370,7 +384,7 @@ mod test {
             }
         }
         let log = Log(expected_traffic_secret);
-        let traffic_secret = ks.derive_logged_secret(kind, &hash, &log, "", &[0; 32]);
+        let traffic_secret = ks.derive_logged_secret(kind, &hash, &log, &[0; 32]);
 
         // Since we can't test key equality, we test the output of sealing with the key instead.
         let aead_alg = &aead::AES_128_GCM;

src/server/tls13.rs

@@ -164,7 +164,6 @@ impl CompleteClientHelloHandling {
                             SecretKind::ClientEarlyTrafficSecret,
                             &client_hello_hash,
                             &*sess.config.key_log,
-                            "CLIENT_EARLY_TRAFFIC_SECRET",
                             &self.handshake.randoms.client);
                     // If 0-RTT should be rejected, this will be clobbered by ExtensionProcessing
                     // before the application can see.
@@ -181,7 +180,6 @@ impl CompleteClientHelloHandling {
             SecretKind::ServerHandshakeTrafficSecret,
             &handshake_hash,
             &*sess.config.key_log,
-            "SERVER_HANDSHAKE_TRAFFIC_SECRET",
             &self.handshake.randoms.client);
         sess.common.set_message_encrypter(cipher::new_tls13_write(suite, &write_key));
 
@@ -189,7 +187,6 @@ impl CompleteClientHelloHandling {
             SecretKind::ClientHandshakeTrafficSecret,
             &handshake_hash,
             &*sess.config.key_log,
-            "CLIENT_HANDSHAKE_TRAFFIC_SECRET",
             &self.handshake.randoms.client);
         sess.common.set_message_decrypter(cipher::new_tls13_read(suite, &read_key));
 
@@ -416,7 +413,6 @@ impl CompleteClientHelloHandling {
             .derive_logged_secret(SecretKind::ServerApplicationTrafficSecret,
                                   &self.handshake.hash_at_server_fin,
                                   &*sess.config.key_log,
-                                  "SERVER_TRAFFIC_SECRET_0",
                                   &self.handshake.randoms.client);
         let suite = sess.common.get_suite_assert();
         sess.common.set_message_encrypter(cipher::new_tls13_write(suite, &write_key));
@@ -439,7 +435,6 @@ impl CompleteClientHelloHandling {
             .derive_logged_secret(SecretKind::ExporterMasterSecret,
                                   &self.handshake.hash_at_server_fin,
                                   &*sess.config.key_log,
-                                  "EXPORTER_SECRET",
                                   &self.handshake.randoms.client);
         sess.common
             .get_mut_key_schedule()
@@ -849,7 +844,6 @@ impl hs::State for ExpectFinished {
             .derive_logged_secret(SecretKind::ClientApplicationTrafficSecret,
                                   &self.handshake.hash_at_server_fin,
                                   &*sess.config.key_log,
-                                  "CLIENT_TRAFFIC_SECRET_0",
                                   &self.handshake.randoms.client);
 
         let suite = sess.common.get_suite_assert();