Real-time electronic signature validation systems and methods

A method for real-time validation of an electronically signature generated onboard a mobile system. The method includes maintaining a ground mobile user account management (GMUAM) module user database to have up-to-date authorized user account information. The GMUAM is hosted by a stationary central computer system (CCS). The method additionally includes transferring the up-to-date authorized user account information stored on the GMUAM user database to a mobile user account management (MUAM) module user database, thereby updating the MUAM user data base with up-to-date authorized user account information. The MUAM module is included in an onboard computer system (OCS) hosted by the mobile system. The method further includes evoking a signature validator module communicatively connected to the MUAM module to access the MUAM database and verify whether user account information included in an electronic signature initiated by a secure data application (SDA) is authorized user account information. The SDA and the signature validator module hosted by the OCS.