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Can You Lock a Lock After Picking it – Reverse Lockpicking

We often talk about picking locks open, but occasionally we are asked if locks can be locked using the same methods. Let's take a look and see what's possible.
reverse lock picking

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Lockpicking allows locks to be bypassed with relatively little evidence, but to truly leave the scene undisturbed, steps must be taken to resecure a lock.

Most common locks you will come across today can be easily relocked after they are opened without a key.  In some instances, locks will automatically reset once closed, while others may need to be picked once more to re-engage the locking mechanism. While in most cases, relocking is always a possibility, there are times where locks are unable to relock even when picked for a second time or when the correct key is used.  This is usually the result of damage caused to the locks during picking, which prevents the lock from turning normally. 

How to relock a picked lock

Locking mechanisms can be divided into three categories depending on how the mechanism is actuated.

One style of these locks, such as those found in most padlocks, uses a spring to return the core to its locked position.  In these locks, it is possible to insert the shackle into the lock and have the mechanism automatically engage and secure the lock in place.

Another popular style includes locks, such as those found in securing door deadbolts, that require the driver pins to be set for the core to rotate and actuate the locking mechanism. The pins must be set again above the shear line to resecure these locks using the correct key or manipulation (such as picking) and the core counter-rotated to relock the door or padlock. 

The final category of keyway is commonly found within bike locks.  These lack a spring mechanism and often will retain the key within the keyway until the lock is secured.  These are relatively easy to relock as the key retention mechanism prevents the pins from moving, meaning all that is required to actuate the lock is to rotate the core back to its original position.

How easy is it to reverse pick?

Reverse picking a lock is just as easy or as difficult as picking the lock open originally and follows an almost identical procedure; however, you will typically have to rotate the core in the opposite direction.

As the process of relocking the keyway requires each pin to be set again, the process is directly tied to the lock’s complexity.  This means cheaper lock cores, such as those produced by Master Lock, maybe resecured in only a few seconds while other locks such as ABUS and Kryptonite require a much more significant time investment.

The biggest challenge that may arise when reverse picking is having to tension the lock in the opposite direction than it was initially picked. This is why training is so essential as almost every lock you face in the real world will be awkwardly placed with limited access to the keyway, so it is essential to familiarize yourself with using picks in unusual positions.

Why is relocking not always possible?

We’ve seen how locks can typically be resecured with relative ease through reverse picking; however, there are times a relocking is not possible.

Lock picking relies on manipulating a keyway in a way that is not normally intended, meaning there is always the risk of the lock becoming damaged.  This risk is present both when opening and closing a lock and is why most lock pickers recommend not practicing on your own locks.

A damaged lock is the worst-case scenario when lock picking as it typically prevents the key from functioning, ultimately requiring the lock to be drilled out and replaced. 

Damage to the keyway can occur in many different ways, but most commonly comes in one of two forms.  The first can happen when too much tension is placed on the core, causing a pin to shatter and block the keyway from turning.  Alternatively, springs may become deformed, preventing the pin from resetting and again obstructing the shear line.

Events such as breaking a pin or spring are relatively rare, however the potential is always there, and it is crucial to be aware of when working in sensitive areas or with locks you rely on daily.

How to detect relocking and protect against it

It is easy to become slightly paranoid with how easy it is to resecure a lock once it has already been open.  What is there to stop someone from attacking a lock then leaving without a trace?

The best way to protect against relocking is by making your lock less of a target to lockpicking and also making your lock harder to pick, as we explored in an earlier article. A more robust lock, which includes security pins, can take considerably longer to pick often meaning a potential attacker will abandon the lock to prevent being caught or detected. 

It is important to realize though, a good lock does not guarantee that the lock cannot be bypassed, and mechanisms exist to detect when a lock has been tampered with and opened.

One of the oldest techniques was prevalent throughout the Soviet Union relied on signed punch cards, which were placed over the keyway.  If the lock was ever opened by a non-authorized person, they would be unable to replace the punch card and therefore leave evidence of tampering, even if the lock was successfully resecured. 

Although this style does prevent direct picking attacks, with the right tools, even this style can be bypassed relatively easily as the LockPickingLawyer demonstrates.

Although not keyed, modern smart-locks also provide a method of detecting tampering and protect against relocking by recording each access via an app. 

These locks still possess multiple vulnerabilities, especially when exposed to magnets; however, they are quickly becoming popular to secure both buildings and gear.

We often talk about picking locks open, but occasionally we are asked if locks can be locked using the same methods. Let's take a look and see if it's possible.

Why is it important to detect relocking?

Knowing how to resecure a lock and how to detect when a lock has been open without your knowledge is extremely valuable. 

From an attacker’s perspective, leaving the scene untouched can play a crucial role in when an attack is detected.  While from a security perspective, the sooner an attack can be identified, the greater the chance that evidence of the attack may be collected and the perpetrator identified.

Detecting tampering as soon as it occurs is of extreme importance as a trained lock picker can leave almost no trace when attacking a lock.  When attacks of this nature do occur, they can often only be proven through forensic lock picking, which involves detailed magnification of the keyway however can often only prove that a lock has been picked and not when and who by.

Clarifying terminology

We’ve thrown around the term reverse lockpicking a lot over this article in reference to the process of locking a previously opened lock; however, if you wish to look into this area more, you will likely come across another use of the term. 

Reverse lockpicking is frequently be used interchangeably with over picking, which is a practice of lock picking in which all pins are lifted above the shear line with heavy tension.  This tension is then gradually relieved, allowing pins to fall into position and ultimately allowing the core to rotate.

While this technique is not very prevalent, a fair amount of information exists online regarding its practice which can make finding information regarding relocking difficult. 

Conclusion

Reverse lock picking is an important skill to remember, particularly when attempting to conceal access to a lock, yet in many cases, it is a relatively straightforward process with many locks engaging automatically. 

Understanding such techniques not only can help when attacking a lock but is just as important when attempting to secure your own lock, as knowing what to look out for could be the difference between detecting an attack now or when it truly matters.

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