parse extension info in MC

fido2/ctap.h

@@ -181,6 +181,11 @@ struct rpId
     uint8_t name[RP_NAME_LIMIT];
 };
 
+typedef struct
+{
+    uint8_t hmac_secret;
+} CTAP_extensions;
+
 typedef struct
 {
     uint32_t paramsParsed;
@@ -201,6 +206,7 @@ typedef struct
     uint8_t pinAuth[16];
     uint8_t pinAuthPresent;
     int pinProtocol;
+    CTAP_extensions extensions;
 
 } CTAP_makeCredential;