diff --git a/connections/implementation/proto/offline_wire_formats.proto b/connections/implementation/proto/offline_wire_formats.proto
index 084c3e58..ea3a1224 100644
--- a/connections/implementation/proto/offline_wire_formats.proto
+++ b/connections/implementation/proto/offline_wire_formats.proto
@@ -43,6 +43,7 @@ message V1Frame {
     KEEP_ALIVE = 5;
     DISCONNECTION = 6;
     PAIRED_KEY_ENCRYPTION = 7;
+    AUTHENTICATION_MESSAGE = 8;
   }
   optional FrameType type = 1;
 
@@ -54,6 +55,7 @@ message V1Frame {
   optional KeepAliveFrame keep_alive = 6;
   optional DisconnectionFrame disconnection = 7;
   optional PairedKeyEncryptionFrame paired_key_encryption = 8;
+  optional AuthenticationMessageFrame authentication_message = 9;
 }
 
 message ConnectionRequestFrame {
@@ -318,6 +320,14 @@ message PairedKeyEncryptionFrame {
   optional bytes signed_data = 1;
 }
 
+// Nearby Connections authentication frame, contains the bytes format of a
+// DeviceProvider's authentication message.
+message AuthenticationMessageFrame {
+  // An auth message generated by DeviceProvider.
+  // To be sent to the remote device for verification during connection setups.
+  optional bytes auth_message = 1;
+}
+
 message MediumMetadata {
   // True if local device supports 5GHz.
   optional bool supports_5_ghz = 1;