  Till now, few work has been done to analyze the performances of joint
fingerprint embedding and decryption schemes. In this paper, the security of
the joint fingerprint embedding and decryption scheme proposed by Kundur et al.
is analyzed and improved. The analyses include the security against
unauthorized customer, the security against authorized customer, the
relationship between security and robustness, the relationship between
secu-rity and imperceptibility and the perceptual security. Based these
analyses, some means are proposed to strengthen the system, such as multi-key
encryp-tion and DC coefficient encryption. The method can be used to analyze
other JFD schemes. It is expected to provide valuable information to design JFD
schemes.
