To help law enforcement officials reduce crime and return recovered property to rightful owners, the city’s Bike Theft Task Force encourages citizens to register their bicycles. The concept is simple: with a serial number, name, phone number, and address in a city database, police can quickly identify owners of recovered property who can then retrieve it.
In a sense, including serial numbers on bicycles or VIN numbers on automobiles is just a way of keeping track of things. Manufacturers want to know products are making it to market. Retailers need to account for the items they sell. Consumers want to return or exchange products, access services, and protect their purchases from damage or theft. The authorities, meanwhile, are interested in monitoring everything from what’s entering and exiting the country through ports to the components used to build airplanes.
The use of serial numbers, barcodes, and radio frequency (RF) identifiers as a means of tracking everything from shipping containers to pets is a time-tested practice. These methods, however, are not without their shortcomings. Barcodes and serial numbers are easy to recognize, alter, replace, or destroy. RF tags are susceptible to human errors in data entry and malfunctions. All three can be removed without causing much damage to the object itself.
At Portland State University, Computer Science Professor Dr. Suresh Singh has developed a method of tagging objects with identifying information that overcomes many of the drawbacks of the existing technologies. When an object is measured by a high-resolution terahertz laser scanner, an algorithm developed by Dr. Singh attributes unique numerical information to tiny bumps and hollows on the object’s surface creating a digital identification tag which can be stored in a database. The information in the tag is static and cannot be changed. Nor can it be read without access to a scanner and the image file in the database. The concept, Dr. Singh noted, was borrowed from the cryptographic practice called steganography wherein messages are “hidden in plain sight.”
Rather than stamping a serial number or barcode as an identification tag on a bicycle, manufacturers could add microscopic surface modifications imperceptible to the human eye somewhere in the frame. With the file identifying the bike uploaded into a cloud-based registry like Bike Index or Project529, consumers and the authorities would have access to information about the make, model, and ownership of any given bicycle.
Embedding identifying information into surface modulations generated during manufacture is one application of this technology. However, according to Dr. Singh, with a terahertz scanner and his algorithm, this method could be applied to anything with some surface depth to it.
“One of the attractive properties of terahertz radiation is that it can pass through objects like x-rays do, but without damaging the object,” Dr. Singh said. “And when you have objects with some depth to their surfaces, like a boutique handbag, an oil painting, or an engine block, a high-resolution terahertz scan at a particular frequency will reflect subtle changes in the layers of depth on the object’s surface. Those reflections are unique to the object, and even unique to the portion of the object scanned. They’re like a signature that we can represent as a series of identifying numbers embedded into an image file of the scan. We can then take these large high-resolution files and run them through cryptographic compression schemes, creating a small file containing the object’s unique signature.”
And just like that, Dr. Singh explained, we could create databases of compressed files containing the identifying information of nearly anything we might want to keep track of and avoid the shortcomings of serial numbers, barcodes, and RF identification tags.
This technology could increase the efficiency of scanning the more than 7 million containers that arrive in U.S. ports each year. With a high-resolution terahertz laser scanner museums, galleries, and private collectors could tag and identify the works in their collections. Fashion designers could turn the contours of a button, clasp, or fabric into an invisible brand that protects retailers and consumers from purchasing counterfeit clothing and apparel. And although the technology wouldn’t end bike theft, it could help Portland’s Bike Theft Task Force and the police return more of the thousands of bicycles they recover each year to their rightful owners.