The Master lock company was founded in 1921, based on Harry Soref's new laminated padlock design, which featured layers of metal wafers riveted together to form the casing of the Master lock. Since then Master has grown to be the world's largest manufacturer of padlocks, supplying over 50 million padlocks in 2005! In America Master easily leads the market and claims to have near total brand recognition. This is largely due to the wide distribution of Master combination locks used in schools to secure student lockers, made possible by their affordability and ease of use.
The classic Master lock that most people will be familiar with, from the corridors of many of America 's schools, is the Master combination lock. This has a normal U-shackle that locks into a round casing which has a circular dial on the front with numbers printed 1 to 40. These have three numbers which the user dials in, rotating the dial two full revolutions to the first number then one full revolution to the second, in the opposite direction, then changing direction again, dialing directly to the third number. Theoretically this provides excellent security with 4 3 combinations: 64,000 unique 3-number combinations.
Unfortunately fact and theory are not the same thing. Due to the tolerance built into the lock one is able to step one number either side of the correct combination for each of the three numbers meaning that only every second number needs to be checked. Still, 32,000 combinations still doesn't sound too bad, right? Unfortunately the design flaws do not end there: Master lock picking is made easy by the fact that the third number - the first picked up by the dial when resetting the lock - can be "heard" while listening closely and manipulating the dial. With sufficient knowledge it is possible to hear the second number also, which leaves only 40 possibilities to try for the first number in the sequence. If you recall you only need to try every second number which means once you have your second two numbers in the sequence, you've only 20 combinations to try. Master lock picking can be completed in about 10 minutes, on average, with sufficient knowledge and practice. This is reduced further by the limited mathematical possibilities created by the internal design of the lock itself: By knowing only the third number which, as stated, is easily heard, it is possible to do a simple web search for the 100 different possible combinations available by just knowing that third number.
In public places like the corridors of a school you may be afforded some security by the fact that someone may not be allowed the ten minutes required to go through all the combinations and surprisingly few people know the technique. Unfortunately Master lock picking knows a third vulnerability: The locking dog of a Master lock can be easily forced open in about two or three seconds with a padlock shim! There are at least two other ways of bypassing the security on this design of lock but they are not within the scope of this brief examination. If you are wondering by now why these locks are used at all their main appeal comes from the fact that they usually retail for less than $15.
It should be noted that Master manufactures many different types of lock and it is only this most widely known one that is so vulnerable to so many different lines of attack. Master offers good product support also. If you are in the unfortunate position of having a lost combination Master lock has an established process for sending you the Master lock combination based on the serial number. Assuming of course you don't simply pick the lock yourself! Master also manufactures other products unrelated to locks at all, such as Master lock trailer balls and similar items.
