Research and Implementation of the Secure Database-Update Mechanism
For a safety critical computer, large-scale data like database which has to be transferred in an instant time cannot be voted directly. This paper proposes a database update algorithm for safety critical computer based on status vote,which is to vote the database status instead of database itself. This algorithm can solve the problem of voting too much data in a short time, and compare versions of database of different modules in real time. A Markov model is built to calculate the safety and reliability of this algorithm. The results show that this algorithm meets the update requirement of safety critical computer. 1. Communication protocol for database update 1.1 TFTP protocol TFTP is a simple protocol for transporting document. It usually uses the UDP protocol to realize but the TFTP does not require the specific agreement of implementation and can implement with TCP in special occasions. [This agreement is designed for small file transferring, so it doesn't have function many FTP usually does; it can only acquire or write the file from the server and not able tot list directory, not authenticate. It transfers 8 bits of data with three models: netascii, the eight-bit ASCII form; octet, the eight-bit source data type; mail, no longer supported, it returns the data back directly to the user rather than saved as a file. 1.2 SRTP Ethernet security real-time data transfer protocol