for my project i produced a security locking device where a new code was generated every hour. it used a one way encryption alogithm, to scramble the time and key data producing a new password. it has a number of features including admin login to generate a new key which was saved in the EEPROM, also lockdown mode if a user had three 'wrong guesses.'' the project came complete with an iphone application with the same algorithm uploaded to the code could be revealed. the algorithm was a mixurture of bitwise and integer arithmatic,