diff --git a/quic/core/handshaker_delegate_interface.h b/quic/core/handshaker_delegate_interface.h
index 03b3af9..0e8e045 100644
--- a/quic/core/handshaker_delegate_interface.h
+++ b/quic/core/handshaker_delegate_interface.h
@@ -30,9 +30,14 @@
       EncryptionLevel level,
       std::unique_ptr<QuicEncrypter> encrypter) = 0;
 
-  // Called to set default encryption level to |level|.
+  // Called to set default encryption level to |level|. Only used in QUIC
+  // crypto.
   virtual void SetDefaultEncryptionLevel(EncryptionLevel level) = 0;
 
+  // Called when both 1-RTT read and write keys are available. Only used in TLS
+  // handshake.
+  virtual void OnOneRttKeysAvailable() = 0;
+
   // Called to discard old decryption keys to stop processing packets of
   // encryption |level|.
   virtual void DiscardOldDecryptionKey(EncryptionLevel level) = 0;
diff --git a/quic/core/http/quic_spdy_session.cc b/quic/core/http/quic_spdy_session.cc
index 8467797..d545b05 100644
--- a/quic/core/http/quic_spdy_session.cc
+++ b/quic/core/http/quic_spdy_session.cc
@@ -764,6 +764,11 @@
   SendInitialData();
 }
 
+void QuicSpdySession::OnOneRttKeysAvailable() {
+  QuicSession::OnOneRttKeysAvailable();
+  SendInitialData();
+}
+
 // True if there are open HTTP requests.
 bool QuicSpdySession::ShouldKeepConnectionAlive() const {
   if (!VersionUsesHttp3(transport_version())) {
diff --git a/quic/core/http/quic_spdy_session.h b/quic/core/http/quic_spdy_session.h
index e7fa037..d1136ff 100644
--- a/quic/core/http/quic_spdy_session.h
+++ b/quic/core/http/quic_spdy_session.h
@@ -323,6 +323,7 @@
       QuicReferenceCountedPointer<QuicAckListenerInterface> ack_listener);
 
   void SetDefaultEncryptionLevel(quic::EncryptionLevel level) override;
+  void OnOneRttKeysAvailable() override;
 
   // Optional, enables instrumentation related to go/quic-hpack.
   void SetHpackEncoderDebugVisitor(
diff --git a/quic/core/http/quic_spdy_session_test.cc b/quic/core/http/quic_spdy_session_test.cc
index b14db0b..a7c36d7 100644
--- a/quic/core/http/quic_spdy_session_test.cc
+++ b/quic/core/http/quic_spdy_session_test.cc
@@ -105,7 +105,12 @@
     }
     EXPECT_THAT(error, IsQuicNoError());
     session()->OnConfigNegotiated();
-    session()->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
+    if (session()->connection()->version().handshake_protocol ==
+        PROTOCOL_TLS1_3) {
+      session()->OnOneRttKeysAvailable();
+    } else {
+      session()->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
+    }
     session()->DiscardOldEncryptionKey(ENCRYPTION_INITIAL);
   }
 
diff --git a/quic/core/http/quic_spdy_stream_test.cc b/quic/core/http/quic_spdy_stream_test.cc
index 707964c..eef43cd 100644
--- a/quic/core/http/quic_spdy_stream_test.cc
+++ b/quic/core/http/quic_spdy_stream_test.cc
@@ -89,7 +89,12 @@
     }
     EXPECT_THAT(error, IsQuicNoError());
     session()->OnConfigNegotiated();
-    session()->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
+    if (session()->connection()->version().handshake_protocol ==
+        PROTOCOL_TLS1_3) {
+      session()->OnOneRttKeysAvailable();
+    } else {
+      session()->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
+    }
     session()->DiscardOldEncryptionKey(ENCRYPTION_INITIAL);
   }
 
diff --git a/quic/core/quic_session.cc b/quic/core/quic_session.cc
index 32e01cb..468bdec 100644
--- a/quic/core/quic_session.cc
+++ b/quic/core/quic_session.cc
@@ -1334,6 +1334,7 @@
 }
 
 void QuicSession::SetDefaultEncryptionLevel(EncryptionLevel level) {
+  DCHECK_EQ(PROTOCOL_QUIC_CRYPTO, connection_->version().handshake_protocol);
   QUIC_DVLOG(1) << ENDPOINT << "Set default encryption level to "
                 << EncryptionLevelToString(level);
   connection()->SetDefaultEncryptionLevel(level);
@@ -1353,19 +1354,8 @@
     case ENCRYPTION_HANDSHAKE:
       break;
     case ENCRYPTION_FORWARD_SECURE:
-      if (connection_->version().handshake_protocol == PROTOCOL_TLS1_3) {
-        QUIC_BUG_IF(!GetCryptoStream()->crypto_negotiated_params().cipher_suite)
-            << ENDPOINT
-            << "Handshake confirmed without cipher suite negotiation.";
-      }
       QUIC_BUG_IF(!config_.negotiated())
           << ENDPOINT << "Handshake confirmed without parameter negotiation.";
-      if (connection()->version().HasHandshakeDone() &&
-          perspective_ == Perspective::IS_SERVER) {
-        // Server sends HANDSHAKE_DONE to signal confirmation of the handshake
-        // to the client.
-        control_frame_manager_.WriteOrBufferHandshakeDone();
-      }
       if (!GetQuicReloadableFlag(quic_bw_sampler_app_limited_starting_value)) {
         connection_->ResetHasNonAppLimitedSampleAfterHandshakeCompletion();
       }
@@ -1376,6 +1366,27 @@
   }
 }
 
+void QuicSession::OnOneRttKeysAvailable() {
+  DCHECK_EQ(PROTOCOL_TLS1_3, connection_->version().handshake_protocol);
+  QUIC_DVLOG(1) << ENDPOINT << "Set default encryption level to "
+                << EncryptionLevelToString(ENCRYPTION_FORWARD_SECURE);
+  connection()->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
+
+  QUIC_BUG_IF(!GetCryptoStream()->crypto_negotiated_params().cipher_suite)
+      << ENDPOINT << "Handshake completes without cipher suite negotiation.";
+  QUIC_BUG_IF(!config_.negotiated())
+      << ENDPOINT << "Handshake completes without parameter negotiation.";
+  if (connection()->version().HasHandshakeDone() &&
+      perspective_ == Perspective::IS_SERVER) {
+    // Server sends HANDSHAKE_DONE to signal confirmation of the handshake
+    // to the client.
+    control_frame_manager_.WriteOrBufferHandshakeDone();
+  }
+  if (!GetQuicReloadableFlag(quic_bw_sampler_app_limited_starting_value)) {
+    connection_->ResetHasNonAppLimitedSampleAfterHandshakeCompletion();
+  }
+}
+
 void QuicSession::DiscardOldDecryptionKey(EncryptionLevel level) {
   if (!connection()->version().KnowsWhichDecrypterToUse()) {
     return;
diff --git a/quic/core/quic_session.h b/quic/core/quic_session.h
index 37c00f7..06dfd0a 100644
--- a/quic/core/quic_session.h
+++ b/quic/core/quic_session.h
@@ -242,6 +242,7 @@
       EncryptionLevel level,
       std::unique_ptr<QuicEncrypter> encrypter) override;
   void SetDefaultEncryptionLevel(EncryptionLevel level) override;
+  void OnOneRttKeysAvailable() override;
   void DiscardOldDecryptionKey(EncryptionLevel level) override;
   void DiscardOldEncryptionKey(EncryptionLevel level) override;
   void NeuterUnencryptedData() override;
diff --git a/quic/core/quic_session_test.cc b/quic/core/quic_session_test.cc
index e3289e9..25237c4 100644
--- a/quic/core/quic_session_test.cc
+++ b/quic/core/quic_session_test.cc
@@ -91,7 +91,12 @@
     }
     EXPECT_THAT(error, IsQuicNoError());
     session()->OnConfigNegotiated();
-    session()->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
+    if (session()->connection()->version().handshake_protocol ==
+        PROTOCOL_TLS1_3) {
+      session()->OnOneRttKeysAvailable();
+    } else {
+      session()->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
+    }
     session()->DiscardOldEncryptionKey(ENCRYPTION_INITIAL);
   }
 
diff --git a/quic/core/tls_client_handshaker.cc b/quic/core/tls_client_handshaker.cc
index 4600986..3782ab5 100644
--- a/quic/core/tls_client_handshaker.cc
+++ b/quic/core/tls_client_handshaker.cc
@@ -400,7 +400,7 @@
   crypto_negotiated_params_->peer_signature_algorithm =
       SSL_get_peer_signature_algorithm(ssl());
 
-  handshaker_delegate()->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
+  handshaker_delegate()->OnOneRttKeysAvailable();
 }
 
 enum ssl_verify_result_t TlsClientHandshaker::VerifyCert(uint8_t* out_alert) {
diff --git a/quic/core/tls_server_handshaker.cc b/quic/core/tls_server_handshaker.cc
index 346e872..715a200 100644
--- a/quic/core/tls_server_handshaker.cc
+++ b/quic/core/tls_server_handshaker.cc
@@ -310,7 +310,7 @@
     app_data_read_secret_.clear();
   }
 
-  handshaker_delegate()->SetDefaultEncryptionLevel(ENCRYPTION_FORWARD_SECURE);
+  handshaker_delegate()->OnOneRttKeysAvailable();
   handshaker_delegate()->DiscardOldEncryptionKey(ENCRYPTION_HANDSHAKE);
   handshaker_delegate()->DiscardOldDecryptionKey(ENCRYPTION_HANDSHAKE);
 }
diff --git a/quic/quartc/quartc_session.cc b/quic/quartc/quartc_session.cc
index 6715ee2..a93f410 100644
--- a/quic/quartc/quartc_session.cc
+++ b/quic/quartc/quartc_session.cc
@@ -185,6 +185,18 @@
   }
 }
 
+void QuartcSession::OnOneRttKeysAvailable() {
+  QuicSession::OnOneRttKeysAvailable();
+  // On the server, handshake confirmed is the first time when you can start
+  // writing packets.
+  DCHECK(IsEncryptionEstablished());
+  DCHECK(OneRttKeysAvailable());
+
+  DCHECK(session_delegate_);
+  session_delegate_->OnConnectionWritable();
+  session_delegate_->OnCryptoHandshakeComplete();
+}
+
 void QuartcSession::CancelStream(QuicStreamId stream_id) {
   ResetStream(stream_id, QuicRstStreamErrorCode::QUIC_STREAM_CANCELLED);
 }
diff --git a/quic/quartc/quartc_session.h b/quic/quartc/quartc_session.h
index 7d0c773..db988a0 100644
--- a/quic/quartc/quartc_session.h
+++ b/quic/quartc/quartc_session.h
@@ -75,6 +75,7 @@
   }
 
   void SetDefaultEncryptionLevel(EncryptionLevel level) override;
+  void OnOneRttKeysAvailable() override;
 
   // QuicConnectionVisitorInterface overrides.
   void OnCongestionWindowChange(QuicTime now) override;
diff --git a/quic/quic_transport/quic_transport_client_session.cc b/quic/quic_transport/quic_transport_client_session.cc
index ae15371..a35d084 100644
--- a/quic/quic_transport/quic_transport_client_session.cc
+++ b/quic/quic_transport/quic_transport_client_session.cc
@@ -104,6 +104,11 @@
   }
 }
 
+void QuicTransportClientSession::OnOneRttKeysAvailable() {
+  QuicSession::OnOneRttKeysAvailable();
+  SendClientIndication();
+}
+
 QuicTransportStream*
 QuicTransportClientSession::AcceptIncomingBidirectionalStream() {
   if (incoming_bidirectional_streams_.empty()) {
diff --git a/quic/quic_transport/quic_transport_client_session.h b/quic/quic_transport/quic_transport_client_session.h
index e4cc15d..56b29e4 100644
--- a/quic/quic_transport/quic_transport_client_session.h
+++ b/quic/quic_transport/quic_transport_client_session.h
@@ -95,6 +95,7 @@
   }
 
   void SetDefaultEncryptionLevel(EncryptionLevel level) override;
+  void OnOneRttKeysAvailable() override;
   void OnMessageReceived(quiche::QuicheStringPiece message) override;
 
   // Return the earliest incoming stream that has been received by the session