A data encryption transmission system and associated methodology is provided including a data input site that compresses and encrypts data based on a shared encryption key and then transmits the compressed and encrypted data to an external network. A database server which is operably linked to the external network and stores, manages, transmits, and receives data. A removable storage stores an identification code, and a client site which is configured to receive the removable storage generates an encryption key based on the identification code, receives encrypted data from the external network, decrypts and expands the received data based on the shared encryption key, encrypts the data based on the encryption key and saves the encrypted data, and finally decrypts the encrypted data and outputs the data using the encryption key.