Security vulnerability analysis of beep sound pattern in digital door lock

Nowadays, digital door look is very popular way for the security of home and office environment since it is easy-to-use and is believed to be safe. Since the sequential numeric input pattern is used as the key in digital door lock, users should remember it and be careful to keep it secure. On the other hand, many digital door locks make beep sound whenever touching a button to give an interactive feedback to the user and to reduce input error. In this paper, security vulnerability of digital door lock with beep sound is analyzed with 14 different test cases based on the assumption that users are enough skilled to their own sequential input pattern so that the speed of user’s fingertip movement is almost constant as the individual maximum speed during touching. The conclusion says that some cases may have relatively weak security level even though it has enough long length passcode. Therefore, the length of input pattern is not proportional to the security level, locally. But, the range of possible number of cases is exponentially proportional to the length of input pattern, globally.