The term keyless locks refer to any of a range of styles and types of locks that can be opened without a conventional bitted key. Usually they take the form of a mechanical combination lock but can also include electronic keyless door locks such as key-card activated locks, electronic combination locks or biometric locks.
If you're after a mechanical combination lock there is a range of options available to you depending on what you need, and what your budget is. At the lower end of the price range, starting as low as US$15, you will be looking at combination padlocks. Popular styles include "sesamee" locks (Sesamee being the most popular brand), which feature three to five wheels on the bottom of the padlock, each with numbers 1-9 engraved in them. If the engineering and machining on a sesamee lock is poor they can be picked fairly easily. The key area to check with these is the gap between each of the wheels and the casing. If you are able to wobble the wheels much, insert a small paperclip into the gap, or a thin flat of metal (say, 0.5mm thickness), then the lock can be easily picked. Other examples of combination keyless locks include padlocks that have a dial with numbers 1-40 on the face, which the user rotates twice in one direction to the first number, once in the opposite direction to the next, and then directly to the third number. (The most popular brand being Master.) These keyless locks are particularly susceptible to cracking as the correct combination can be "heard" just by listening closely while manipulating the dial. These combination locks are not suitable for most applications as they work with a shackle, restricting their use as keyless entry locks to gates, lockers, and cabinets. Unless they are especially well made they can only guarantee a low level of security.
If you wish to go further up the scale keyless door locks can be bought for between $90 and $250. These usually feature a keypad of some sort where a user depresses the buttons in sequence to enter their combination and gain access. Some of these are quite good; however, you should never purchase a keyless door lock that does not allow you to change the combination. The default codes for some of these locks are easily available online, as are instructions for hacking them. One particular line of keyless entry locks which saw massively widespread use were the Simplex 900 series keyless locks. All 2164 default combinations for these locks have been available online for years, as a quick web search will show. Although Simplex has since released some good locks the 900 series was a joke and should be avoided at all costs.
Keyless locks are susceptible to all the same circumvention methods that can be employed against conventional locks, such as a brute force attack. Therefore with any keyless door lock it is important that the lock assembly has several good fasteners to the door frame and that the lock itself has a sturdy construction. Products described as keyless deadbolt locks usually perform well in this regard.
If you're willing to go even further still up the scale then you're entering the realm of electronic keyless door locks. There are a few types available with the two most popular configurations being electronic combination locks which can start as low as $150 - although you should expect to pay more for a good one - and can go far upwards of $400 for the premium quality models. With recent rapid advances in computing and decreasing prices of electronic hardware, biometric door locks are also becoming increasingly popular and affordable. These locks work by recording key parts of the fingerprint of authorized personnel and comparing it with the impression of scanned fingerprints. They are now reliable enough to be used for high security applications with the prices starting at less than $350 and going well over $1000. The feature set grows with the more expensive models. These are not widely enough used for empirical evidence of the difficulty in hacking these locks to exist, however the mere sight of a high-tech lock like this often serves as a deterrent in itself.
