diff --git a/nugget/proto/nugget/app/keymaster/keymaster.options b/nugget/proto/nugget/app/keymaster/keymaster.options
index b960049..2081eaf 100644
--- a/nugget/proto/nugget/app/keymaster/keymaster.options
+++ b/nugget/proto/nugget/app/keymaster/keymaster.options
@@ -5,3 +5,7 @@
 nugget.app.keymaster.SetBootStateRequest.public_key max_size:32
 nugget.app.keymaster.ComputeSharedHmacRequest.hmac_sharing_params max_count:3
 nugget.app.keymaster.ComputeSharedHmacResponse.sharing_check max_size:32
+nugget.app.keymaster.DTupHandshakeRequest.nonce_client max_size:32
+nugget.app.keymaster.DTupHandshakeResponse.nonce_citadel max_size:32
+nugget.app.keymaster.DTupHandshakeResponse.signature max_size:32
+nugget.app.keymaster.DTupFetchInputEventResponse.signature max_size:32
diff --git a/nugget/proto/nugget/app/keymaster/keymaster.proto b/nugget/proto/nugget/app/keymaster/keymaster.proto
index 256031b..c85af6e 100644
--- a/nugget/proto/nugget/app/keymaster/keymaster.proto
+++ b/nugget/proto/nugget/app/keymaster/keymaster.proto
@@ -85,6 +85,12 @@
    */
   rpc GetHmacSharingParameters (GetHmacSharingParametersRequest) returns (GetHmacSharingParametersResponse);
   rpc ComputeSharedHmac (ComputeSharedHmacRequest) returns (ComputeSharedHmacResponse);
+
+  /*
+   * DTup input session methods.
+   */
+  rpc HandshakeDTup (DTupHandshakeRequest) returns (DTupHandshakeResponse);
+  rpc FetchDTupInputEvent (DTupFetchInputEventRequest) returns (DTupFetchInputEventResponse);
 }
 
 /*
@@ -323,3 +329,21 @@
   ErrorCode error_code = 1;
   bytes sharing_check = 2;
 }
+
+message DTupHandshakeRequest {
+  bytes nonce_client = 1;
+}
+
+message DTupHandshakeResponse {
+  DTupError error_code = 1;
+  bytes nonce_citadel = 2;
+  bytes signature = 3;
+}
+
+message DTupFetchInputEventRequest {}
+
+message DTupFetchInputEventResponse {
+  DTupError error_code = 1;
+  DTupKeyEvent event = 2;
+  bytes signature = 3;
+}
diff --git a/nugget/proto/nugget/app/keymaster/keymaster_defs.proto b/nugget/proto/nugget/app/keymaster/keymaster_defs.proto
index c3fbbc8..5958838 100644
--- a/nugget/proto/nugget/app/keymaster/keymaster_defs.proto
+++ b/nugget/proto/nugget/app/keymaster/keymaster_defs.proto
@@ -263,3 +263,16 @@
   PKCS8 = 1;  /* for asymmetric key pair import */
   RAW = 3;    /* for symmetric key import and export*/
 }
+
+enum DTupError {
+  DTUP_OK = 0;
+  DTUP_NO_EVENT = 1;
+}
+
+/* matches Linux event device codes */
+enum DTupKeyEvent {
+    DTUP_RESERVED = 0;
+    DTUP_VOL_DOWN = 114;
+    DTUP_VOL_UP = 115;
+    DTUP_PWR = 116;
+}