Safe-cracking is the process of opening a
Different procedures may be used to crack a safe, depending on its construction. Different procedures are required to open different safes so safe-crackers need to be aware of the differences.
Lock manipulation is the stereotypical safe cracking technique commonly portrayed in movies. It's a damage free combination recovery method, and a well known surreptitious bypass technique. Manipulation only requires fingers, eyes, and proper technique but it's a skill that takes years to develop and decades to master. Manipulation is a Group 2 mechanical lock bypass method. Expert practitioners of this art can open locks with speed and consistency. These professionals manually manipulate  the
Mechanical safe locks are manipulated primarily by feel and vision, with sound helping the process occasionally. To find the combination the operator uses the lock against itself by measuring internal movements with the dial numbers. More sophisticated locks use advanced mechanics to eliminate any feedback a technician could use to identify a combination. These group 1  locks were developed in response to group 2 lock manipulation and can be identified by the lack of feeling in the dial or by a push/turn dial. Wheels made from lightweight materials will reduce valuable sensory feedback, but are mainly manufactured as X-ray resistant locks.  Manipulation is often the preferred choice in lost-combination lockouts, since it requires no repairs or damage, but can be time consuming for an operator, the specific difficulty depends on the unique wheel shapes and where the gates rest in relation to them. A novice's opening time will be governed by these random inconsistencies, while some leading champions of this art show admirable consistency. There are also a number of tools on the market to assist safe engineers in manipulating a combination lock open in the field.
Nearly all combination locks allow some "slop" while entering a combination on the dial. On average expect 1% radial rotation in either direction from the center of the true combination number to allow the fence to fall despite slight deviation. so that for a given safe it may be necessary only to try a subset of the combinations. Such "slops" may allow for a margin of error of plus or minus two digits, which means that trying multiples of five would be sufficient in this case. This drastically reduces the time required to exhaust the number of meaningful combinations. A further reduction in solving time is obtained by trying all possible settings for the last wheel for a given setting of the first wheels before nudging the next-to-last wheel to its next meaningful setting, instead of zeroing the lock each time with a number of turns in one direction.
Safes may be compromised surprisingly often by simply guessing the combination. This results from the fact that manufactured safes often come with a manufacturer-set combination. These combinations (known as try-out combinations) are designed to allow owners initial access to the safes so that they may set their own new combinations. Sources exist which list manufacturers' try-out combinations.
Combinations are also unwittingly compromised by the owners of the safes by having the locks set to easy-to-guess combinations such as a birthdate, street address, or driver's license number.
A number of companies and groups have developed autodialing machines to open safes. Unlike fictional machines that can open any combination in a matter of seconds, such machines are usually specific to a particular type of lock and must cycle through thousands of combinations to open a device. A good example of such a device is a project completed by two students from the
There also exist computer-aided manipulation tools such as Mas Hamilton's SoftDrill (no longer in production) and Cygnus. These tools are like autodialers except they listen to the lock, and, with the aid of a computer, make logical decisions like a human manipulator would.
While some safes are hard to open, some are susceptible to compromise by
In observational attacks, the drill hole allows the safecracker to view the internal state of the combination lock. Drill-points are often located close to the axis of the dial on the combination lock, but observation may sometimes require drilling through the top, sides or rear of the safe. While observing the lock, the locksmith manipulates the dial to align the lock gates so that the fence falls and the bolt is disengaged.
Bypass attacks involve physical manipulation of the bolt mechanism directly, bypassing the combination lock.
All but the simplest safes are designed to protect against drilling attacks through the implementation of hardplate steel (extremely wear-resistant) or composite hardplate (a casting of metal such as cobalt-vanadium alloys with embedded
Drilling is an attractive method of safecracking for locksmiths, as it is usually quicker than manipulation, and drilled safes can generally be repaired and returned to service.
Punching, peeling and using a torch are other methods of compromising a safe. The punch system is widely used by criminals for rapid entry. Punching was developed by
Scoping a safe is the process of drilling a hole and inserting a
Other methods of cracking a safe generally involve damaging the safe so that it is no longer functional. These methods may involve
Most modern safes are fitted with 'relockers' (like the one described above) which are triggered by excessive force and will then lock the safe semi-permanently (a safe whose relocker has tripped must then be forced, the combination or key alone will no longer suffice). This is why a professional safe-technician will use manipulation rather than brute force to open a safe so they do not risk releasing the relocker.
Penetrating radiation such as
A number of inexpensive safes sold to households for under $100 use mechanical locking mechanisms that are vulnerable to bouncing. Many cheap safes use a magnetic locking pin to prevent lateral movement of an internal locking bolt, and use a