Security through obscurity

Security through obscurity is a specific practice used in security engineering. It involves concealing the details or the internal mechanisms of a system to make it more secure. This approach relies on the principle of hiding things in plain sight. You can compare it to a magician using sleight of hand or a soldier using camouflage. Instead of using physical barriers like heavy locks, this method focuses on obscuring information. The goal is to make the system's workings less visible or harder to comprehend. This reduces the likelihood that someone will perform unauthorized access or manipulation.

The mechanism of obscurity works by making the path to a secret difficult to find. One method is disguising sensitive information within very common items. For example, a person might hide a secret note inside a regular book. In the digital world, this might involve spoofing a web browser's version number. Spoofing means changing digital footprints to make a device look like something else. This creates a layer of confusion for potential threats. However, this is not considered a standalone solution. It is most effective when it complements other, stronger security measures.

There are different ways to view the role of obscurity in design. Some people view it as an independent layer of defense. In this view, making things hard to find is a valid tool on its own. However, many experts prefer "security by design" or "open security." These methods focus on building strength into the system itself. There is also a modern approach called Moving Target Defense. This is an advanced version of obscurity used in cybersecurity. It works by constantly changing the system to stay ahead of attackers. Another method is cyber deception, which uses misleading information to trick threats.

History provides important lessons about the limits of hiding secrets. In 1851, a locksmith named Alfred Charles Hobbs challenged the idea of secret designs. He demonstrated to the public how to pick state-of-the-art locks. Hobbs believed that criminals were already very skilled at their jobs. He argued that thieves already knew more than designers could teach them. This event highlighted the danger of relying on secret mechanisms. Later, Kerckhoffs' doctrine was established in the nineteenth century. This doctrine states that a system's security should depend on its key. The design of the system should remain known and not be obscure.

Modern standards bodies strongly discourage using obscurity as a single defense. The National Institute of Standards and Technology, or NIST, provides clear guidance. They state that system security should not depend on the secrecy of its components. In the digital world, the Common Weakness Enumeration project labels this mistake as CWE-656. This means relying on obscurity is a recognized weakness in software. Many systems have tried to use this method and failed. This includes components of GSM and GPRS encryption. It also includes GMR encryption and various RFID encryption schemes. Even the Terrestrial Trunked Radio, or TETRA, system has been broken.

One common example of this practice is found in anti-malware software. These programs often use secret signatures to flag dangerous files. However, this often leads to a digital arms race. Attackers find new ways to avoid detection by the secret signatures. Then, defenders must create even more complex and secret signatures to catch them. This creates a single point of failure. If the secret method is discovered, the entire defense fails. This cycle shows why relying on hidden details is often a losing battle.

Understanding obscurity helps us see how different security fields connect. It relates to the study of steganography, which is hiding messages inside other data. It also connects to software obfuscation, which makes code difficult for humans to read. In the computing history of MIT, the term had a unique meaning. Users of the Incompatible Timesharing System, or ITS, used the term self-mockingly. They used it to describe their own poor documentation and obscure commands. This shows that obscurity can exist in both intentional security and accidental confusion. Whether intentional or not, obscurity changes how people interact with a system.