Abstract: Protocol fuzz testing can effectively detect vulnerabilities in network software,whereas when facing encryption and checksum mechanisms,existing approaches are hard to generate valid test data．A test case generation method based on “decomposition and reconstruction” was proposed．By means of detection technology on check point and decrypted memory,the valid decoded test data was decomposed at test side．A memory-backtracking algorithm was also proposed,which detects the memory none of the duplication of other memories at the other side,based on which the encoded test packet is reconstructed．Case study and comparison test demonstrate that the method can effectively generate test cases.

Key words: Fuzz testing,Taint analysis,Encryption mechanism,Authentication mechanism,Symbolic execution