diff --git a/dap-sdk/crypto/include/dap_sign.h b/dap-sdk/crypto/include/dap_sign.h
index 85d4458dc238cc68960c6af82f9b83117a4dec9e..9182a7e10ba067e1c8e91394c99d601df78f3823 100755
--- a/dap-sdk/crypto/include/dap_sign.h
+++ b/dap-sdk/crypto/include/dap_sign.h
@@ -49,6 +49,7 @@ typedef union dap_sign_type {
 
 typedef struct dap_sign_hdr {
         dap_sign_type_t type; /// Signature type
+        uint16_t padding;
         uint32_t sign_size; /// Signature size
         uint32_t sign_pkey_size; /// Signature serialized public key size
 } DAP_ALIGN_PACKED dap_sign_hdr_t;