In the realm of door locks and deadbolts, there are those that give low lives and thieves pause. Medeco, Mul-T-Lock, Abloy—these names strike fear and despair into their very hearts.
High-security door locks are a different breed—separate from the typical locks you find littering the hardware stores with the words “high-security rating” plastered all over the box.
But that begs the question. What is a high-security door lock?
A true high-security door lock has the following:
- A Patented Keyway/Key Control: The duplication of keys is controlled. Each high-security lock has a special key design that is protected from unauthorized duplication by a patent. You can’t bring a high-security key to your local hardware store or Home Depot to be copied. Rather you’ll need a locksmith with the appropriate license and key machine to make you a copy. Additionally, for most high-security keys, you’ll need to present an ID card proving that you own that key and lock.
- Highly Resistant to Manipulation: High-security locks use a variety of methods to discourage lock manipulation tactics such as lock picking or lock bumping. This is typically accomplished through using additional locking systems (such as sidebars), security pins, rotating pins, tight tolerances, and restrictive keyways. In high-security locks, this can be represented by a UL437 rating.
- Drilling/Destructive Force Countermeasures: High-security locks use ball bearings, steel rods, and other hardened steel reinforcements to protect vital areas against drilling and other destructive attacks. In high-security locks, this can be represented by an ANSI Grade 1 (or sometimes a Grade 2) lock body.
In this guide, we'll dive into the best high-security door locks on the market—updated for 2023! I have hand selected each of the following products based on my own experience bypassing locks—as well as other characteristics such as the three criteria above.
If a true high-security lock is a little more than you need, consider checking out my guide covering the best deadbolts of 2023, where I review tamer options that still provide great home security!
Before we jump into the locks, it’s important to state that even the best door lock will provide poor security on a weak door.
What Are the Best High-Security Door Locks?
Sorting this list was a relatively difficult task. I did my best to keep the average consumer in mind and sorted them from best to worst based roughly upon strength, vulnerabilities, features, availability, and average price.
Here are the best high-security door locks on the market today!
Best High Security Door Lock Reviews
1. Mul-T-Lock MT5+ Hercular
Next up is the infamous Mul-T-Lock MT5+ Hecular. This high-security dimple lock is an absolute workhorse, and even in the vast world of lock picking, there are few elites that can open these locks.
It uses Mul-T-Lock’s patented MT5+ key cylinder, which is UL437 rated, offers intense pick resistance and key control, and has some unique master keying features.
The average price to copy an MT5+ key is about $30, and the patent for the keyway expires in 2025. Like all patented keyways, you'll have to provide an ID card proving you own the lock (which comes with the lock).
Mul-T-Lock's MT5+ cylinder can be used in other types of locks, including padlocks. So you can have all your locks keyed alike and protected with the same patented key.
- Patented Keyway: MT5+ (MTL800)
- Patent Expires: 2025
- Average Price to Duplicate Key: $30
- UL437 Rated: Yes
- ANSI Rating: Grade 1
Lock Body/Hardware Characteristics:
This door lock uses Mul-T-Lock’s Hecular deadbolt lock body and is ANSI grade 1 security rating—which is perfect for heavy-duty commercial use.
It has a 1“ reinforced bolt with an anti-drill ring and two hardened ball bearings on the end that grasp the strike and increase resistance to jimmying/prying.
The Hecular can be purchased as a single cylinder deadbolt or double cylinder.
- Adjustable backset: 2⅜" (60 mm) or 2¾" (70 mm)
- Door width: 1⅜" (35 mm) to 1¾" (45 mm)
Manipulation Resistance/Cylinder Features:
Where this lock truly shines it's patented MT5+, which is highly pick resistant and provides excellent key control.
Mul-T-Lock also has incredibly high standards and manufactures their locks with tight tolerances. This is important between extra space and slop between components generally makes exploiting locks eaiser.
On top of quality manufacturing, it utilizes a few additional security features.
- Telescopic pins: Pin-in-pin technology that aids in pick resistance. Can be counter-milled to seize up if under tension.
- Sidebar: In a nutshell, it's two locks in one! A sidebar is an additional locking mechanism 90 degrees perpendicular to the primary key pins. It uses side pins (also referred to as finger pins) that interact with a milled track on the side of the key.
- Countermilling: Increases pick resistance by threading the pin chambers to seize pins while being lifted under tension.
- Patented Alpha Spring: This is a moving component on the key and interacts with a pin at the rear of the keyway. This further restricts the possibility of unwanted duplicate keys.
It also uses Mul-T-Lock’s 3-in-1 keying feature, which allows you to quickly rekey a cylinder twice by simply turning the key.
Vulnerabilities and Points of Concern
There aren't any major vulnerabilities of the MT5+ Hecular. It can be picked, but all locks can, and this one, in particular, is a true challenge for even the best locksmiths and hobby pickers.
There are also a few known attacks that can disable the sidebar (such as a vibration attack). If the sidebar is compromised, the lock becomes significantly easier to bypass.
My main concern is the patent itself, which expires in 2025 with no known extension. At this point, key control becomes a major issue, and more vulnerabilities will likely arise.
Overall, MT5+ is a formidable lock that very few people have the skill to compromise.
What I Like / Dislike about the Mul-T-Lock MT5+ Hercular
Reasons to Buy:
- Patented Keyway
- UL437 rated and ANSI Grade 1
- Highly resistant to picking
- MT5+ utilizes sidebars, telescopic pins, countermilling, and a patented alpha spring
- MT5+ cylinder can be used in multiple types of locks, including padlocks. So you can have all your locks keyed alike
- Supports large and complex master key systems
Reasons to Avoid:
- The patent expires in 2025
2. Medico M4
The Medeco M4 is the newest patented cylinder from ASSA ABLOY and is a welcome upgrade to one of the most used high-security locks in the world, the M3.
This beast is secured by two primary locking mechanisms, a sidebar, and a moveable element on the key that further protects the lock against cloned or 3D printed keys. More on that below.
Medeco 4 keys cost on average $35 USD to duplicate, and the patent expires in 2040, giving the key control for this lock a long life.
The M4 cylinder is also available in other formats—including padlocks—so you can use a single key for multiple applications.
Buying Note: At the time of writing this, the M4 isn't for sale online, and you’ll have to acquire one through an authorized dealer—which you can find through the Medeco website here.
- Patented Keyway: M4
- Patent Expires: 2040
- Average Price to Duplicate Key: $35
- UL437 Rated: Yes
- ANSI Rating: Grade 1
Lock Body/Hardware Characteristics:
The Medeco M4 door lock is an ANSI Grade 1 deadbolt with a re-inforced anti-drill faceplate to protect vital areas such as the keyway, pin stacks, and mounting screws.
It has a 1“ hardend steel bolt that is virtually sawprof and a steel shrouding to protect it against ice pick and prying attacks.
The Maxum is easy to install and can be installed like any other regular deadbolt.
- Adjustable Backset: 2⅜" (60 mm) or 2¾" (70 mm)
- Door Width: 1⅜" (35 mm) to 1¾" (45 mm)
Manipulation Resistance/Cylinder Features:
The Medeco M4 is UL 437 listed; giving it great protection against drilling, picking, and other common physical attacks.
Its resistance to manipulation and excellent key control is a result of features including:
- Biaxial Pins: The internal pins have chiseled angles that, when met with the correct key, rotate pins left or right while lifting them. Meanwhile, the pins in traditional lock cylinders only have to be lifted. Biaxial pins add significant complexity to picking and are common in Medeco locks.
- Secondary Sliders: The M4 uses a secondary set of pins (called sliders) that interact with a groove on the side of the key.
- Sidebar: The secondary set of pins have gates (notches) on them. When the slider pins are lifted to the correct heights, the sidebar is allowed to retract and the lock to open.
- Shuttle Pin: A moveable stainless steel element on the side of the key that interacts with the slider pins and protects the lock against 3D copied keys and other types of clones.
Each of the above features has variations that can be used, which results in an insane nine million possible key combinations. The average house lock has 100,000 possible combinations.
Vulnerabilities and Points of Concern
While the M4 is ANSI Grade 1 and UL 437 listed, it is not impervious to picking, and it’s certainly not the top dog on this list for strength or manipulation resistance.
That being said, this lock is extremely hard to pick and requires a level of skill that 99.9% of lockpickers never reach.
I don’t have any true concerns over the Medeco 4. It’s a quality lock and a great entry-level option from a company that has an excellent reputation for listening to feedback and fixing known issues—as they did in their M3 cylinder.
If at any time a fatal flaw is discovered, I’ll be sure to update this accordingly.
What I Like / Dislike about the Medico M4
Reasons to Buy:
- Patented Keyway; expires 2040
- UL437 rated and ANSI Grade 1
- Highly resistant to picking
- Utilizes biaxial pins, secondary sliders, a sidebar, and a movable element on the key (shuttle pin)
- Can be used in multiple types of locks, including padlocks. So you can have all your locks keyed alike
- Supports large and complex master key systems
Reasons to Avoid:
- Not the strongest or most pick-resistant high-security lock
- Relatively new and harder to acquire
3. Mul-T-Lock Interactive+ Cronus
The Mul-T-Lock Interactive+ Cronus is the predecessor of the MP5+ (#3 lock on this list). However, unlike the MP5+, the Interactive cylinder contains no sidebar or alpha pin.
The lack of these features makes it a less secure and cheaper option than the newer MP5+ model, but it's still a highly resilient lock that will give many of the best lock pickers and security exploiters a run for their money.
The average price to copy an Interactive key is about $20 USD, and the keyway patent expires in 2025 with no known extension. This cylinder has recently been rebranded, so you might find also find it under the name MTL600.
- Patented Keyway: Interactive+ (MTL600)
- Patent Expires: 2025
- Average Price to Duplicate Key: $20
- UL437 Rated: No
- ANSI Rating: Grade 2
Lock Body/Hardware Characteristics:
The Interactive+ deadbolt uses Mul-T-Lock’s Grade 2 Cronus lock body, which isn't ideal for commercial use. However, it's still an impressively reinforced deadbolt that's perfect for high-security residential use.
It has a steel rosette with a hardened anti-drill plate and a full 1“ bolt which is reinforced with a hardened steel insert.
- Adjustable Backset: 2⅜" (60 mm) or 2¾" (70 mm)
- Door Width: 1⅜" (35 mm) to 1¾" (45 mm)
Manipulation Resistance/Cylinder Features:
While the interactive cylinder is not pick-proof (no lock is) nor bump-proof, it is still a formidable opponent against even the best and most skilled lock pickers.
Mul-T-Lock also has incredibly high standards and manufactures their locks with tight tolerances.
On top of quality manufacturing, it utilizes a few additional security and key control features.
- Telescopic pins: Pin-in-pin technology that aids in pick resistance. Can be counter-milled to seize up if under tension.
- Countermilling: Increases pick resistance by threading the pin chambers to seize pins while being lifted under tension.
One benefit of Mul-T-Lock’s cylinders is their adaptability. They can easily be thrown into other types of locks, including padlocks—giving you the ability to run all of your locks off a single key.
Vulnerabilities and Points of Concern
My main concern with the Mul-T-Lock Interactive+ Cronus is the ANSI Grade 2 deadbolt lock. While this is one of the best door locks for home security, it should not be used commercially. I would recommend the new Grade 1 Hecular for commercial utility over this one.
It also has quite a few known vulnerabilities. It can be impressioned, bumped, and picked; however, it does take an incredible amount of skill to do so, and these vulnerabilities would only truly concern me if the lock was being used commercially.
Another point of concern is the patent which expires in 2025 with no known extension. When the patent expires, people will have free access to key blanks, and key control becomes an issue.
Overall, the Interactive+ Cronus high-security deadbolt is a great option to keep your home safe and sound!
What I Like / Dislike about the Mul-T-Lock Interactive+ Cronus
Reasons to Buy:
- Patented Keyway
- Highly resistant to picking
- Utilizes telescopic pins and countermilling
- Can be used in multiple types of locks, including padlocks.
- Supports large and complex master key systems
Reasons to Avoid:
- The patent expires in 2025
- ANSI Grade 2
