However, withdrawal from caffeine is seldom dangerous, though it can make one uncomfortable for a few days. The most frequent symptom associated with this withdrawal is a moderate to severe headache. This can occur between 12 and 24 hours after last intake of caffeine.
Make sure you have cheats ON and say /give (player name) command_block. After you get in in your inventory place 5 in a row. Then you right click the first one and put the command /give @a 306. Then exit out of that command block and right click the next one.
You can now create passwords with command blocks, using /testforblock. Place a command block. This will be the one you put input in. Place another command block, and type in the command /testforblock (x,y,z of first command block) command_block 0 {Command:(input)}.