diff --git a/codegen/auth_enclave/bindings.h b/codegen/auth_enclave/bindings.h
index eba213e9..9820e422 100644
--- a/codegen/auth_enclave/bindings.h
+++ b/codegen/auth_enclave/bindings.h
@@ -12,6 +12,8 @@
  */
 #define DATA_UPLOAD_RESPONSE_LEN (16 + (24 + 16))
 
+#define ARCHIVED_ENCLAVE_ID_SIZE 8
+
 #define SET_ACCESS_KEY_REQUEST_SIZE 40
 
 #define SET_ACCESS_KEY_RESPONSE_SIZE 1
diff --git a/codegen/data_enclave/bindings.h b/codegen/data_enclave/bindings.h
index e0c026ed..63570f99 100644
--- a/codegen/data_enclave/bindings.h
+++ b/codegen/data_enclave/bindings.h
@@ -12,6 +12,8 @@
  */
 #define DATA_UPLOAD_RESPONSE_LEN (16 + (24 + 16))
 
+#define ARCHIVED_ENCLAVE_ID_SIZE 8
+
 #define SET_ACCESS_KEY_REQUEST_SIZE 40
 
 #define SET_ACCESS_KEY_RESPONSE_SIZE 1
diff --git a/codegen/exec_enclave/bindings.h b/codegen/exec_enclave/bindings.h
index eba213e9..9820e422 100644
--- a/codegen/exec_enclave/bindings.h
+++ b/codegen/exec_enclave/bindings.h
@@ -12,6 +12,8 @@
  */
 #define DATA_UPLOAD_RESPONSE_LEN (16 + (24 + 16))
 
+#define ARCHIVED_ENCLAVE_ID_SIZE 8
+
 #define SET_ACCESS_KEY_REQUEST_SIZE 40
 
 #define SET_ACCESS_KEY_RESPONSE_SIZE 1
diff --git a/rtc_types/src/enclave_messages/ffi_set_access_key.rs b/rtc_types/src/enclave_messages/ffi_set_access_key.rs
index 2c7b27b2..aed70674 100644
--- a/rtc_types/src/enclave_messages/ffi_set_access_key.rs
+++ b/rtc_types/src/enclave_messages/ffi_set_access_key.rs
@@ -13,6 +13,9 @@ use sgx_types::sgx_aes_gcm_128bit_tag_t;
 
 use super::{set_access_key, RecommendedAesGcmIv};
 
+// See enclave_messages::ARCHIVED_ENCLAVE_ID_SIZE
+pub const ARCHIVED_ENCLAVE_ID_SIZE: usize = 8;
+
 // Begin FFI types
 // (Keep these FFI type comments in sync between set_access_key and ffi_set_access_key, for diffing!)
 
@@ -24,7 +27,7 @@ pub const SET_ACCESS_KEY_REQUEST_SIZE: usize = 40;
 pub struct SetAccessKeyEncryptedRequest {
     pub tag: sgx_aes_gcm_128bit_tag_t,
     pub ciphertext: [u8; SET_ACCESS_KEY_REQUEST_SIZE],
-    pub aad: [u8; 0],
+    pub aad: [u8; ARCHIVED_ENCLAVE_ID_SIZE],
     pub nonce: RecommendedAesGcmIv,
 }
 
diff --git a/rtc_types/src/enclave_messages/set_access_key.rs b/rtc_types/src/enclave_messages/set_access_key.rs
index fdb40a3f..544e2935 100644
--- a/rtc_types/src/enclave_messages/set_access_key.rs
+++ b/rtc_types/src/enclave_messages/set_access_key.rs
@@ -24,7 +24,7 @@ pub struct Response {
 pub const REQUEST_SIZE: usize = mem::size_of::<ArchivedRequest>();
 
 // FFI type: EncryptedRequest
-pub type EncryptedRequest = EncryptedEnclaveMessage<REQUEST_SIZE, 0>;
+pub type EncryptedRequest = EncryptedEnclaveMessage<REQUEST_SIZE, ARCHIVED_ENCLAVE_ID_SIZE>;
 
 // FFI type: RESPONSE_SIZE
 pub const RESPONSE_SIZE: usize = mem::size_of::<ArchivedResponse>();