Safe-cracking is the process of opening a safe, generally without the authorisation or knowledge of the safe's owner. It may also refer to a computer hackers attempts to break into a secured computer system.

Physical safe-cracking

Different procedures may be used to crack a safe, depending on its construction.

Lock manipulation

The most surreptitious way of cracking a safe is to manipulate the lock in order to obtain the combination required to open the safe without actually damaging the safe. Some rotary combination locks can be manipulated by feel or sound in order to determine the combination required to open the safe.

Guessing or stealing the combination

A safe may be compromised suprisingly often by guessing the combination. This results from the fact that manufactured safes often come with a manufacturer-set combination. This combination is designed to allow the owner initial access to the safe so that they may set their own new combination. Often the new owner will not change the initial combination, so a knowledge of the manufacturer's set combinations may enable access to a safe.

Sources exist which list manufacturers' try-out combinations.

Another known way to obtain the combination is to steal it. A safe is only as secure as its combination.

Compromising a weak point on the safe (Drilling)

Most safes are susceptible to compromise by drilling or other physical methods. Manufacturers publish drill-point diagrams for specific models of safe. These are tightly guarded by both the manufacturers and locksmithing professionals. Drilling is usually aimed at gaining access to the safe by observation or bypass of the locking mechanism.

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 within the safe, protecting the locking mechanism. The use of hardplate ensures that conventional drilling is not successful when used against the safe. Drilling through hardplate requires the use of special-purpose diamond or tungsten-carbide drill-bits.

Some high security safes use what is called a glass relocker. It is a piece of tempered glass mounted between the safe door and the combination lock. It has wires attached to the edges. These wires lead to randomly located, spring-loaded bolts. If an attempt is made to penetrate the safe, the drill or torch breaks the glass allowing the bolts to fire. These bolts block the retraction of the main safe bolts. To drill a safe with a glass relocker side, top or rear drilling may be necessary.

Drilling is an attractive method of safecracking, 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.

Peeling involves removing the outer skin of the safe.

Plasma cutters and thermal lances are hotter than oxy-acetylene torches and can be used to burn through the metal on a safe.

Brute force methods

Other methods of cracking a safe generally involve damaging the safe so that it is no longer functional. These methods may involve explosives or other devices to inflict severe force and damage the safe so it may be opened. This method requires care as the contents of the safe may be damaged. Safe-crackers can use what are known as jam shots to blow off the safe's doors.

Tunnelling into bank vaults

Large bank vaults which are often located underground have been compromised by safe-crackers who have tunnelled in using digging equipment. This method of safe-cracking has been countered by building patrol-passages around the underground vaults. These patrol-passages allow early detection of any attempts to tunnel into a vault.

More modern safes are better designed and thus harder to crack.

Safe-cracking in movies

Movies often depict a safe-cracker determining the combination of a safe lock using their fingers or a sensitive listening device to determine the combination of a rotary combination lock.

Some of the more famous movies include:

• Safe Men
• Ocean's Eleven
• Hudson Hawk
• The Italian Job remake (2003)

See also

• Security engineering

External links

• How Safecracking works
• Matt Blaze's paper Safecracking for Computer Scientists draws analogies between physical safecracking and computer security
• How to crack house safes
• A lecture by Tim Hunkin on safe-cracking history and modern safe engineering