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Tamper-evident describes a device or process that makes unauthorized access to the protected object easily detected. Seals, markings, or other techniques may be tamper indicating.
Tampering involves the deliberate altering or adulteration of information, a product, a package, or system. Solutions may involve all phases of product production, distribution, logistics, sale, and use. No single solution can be considered as "tamper proof". Often multiple levels of security need to be addressed to reduce the risk of tampering. [1]
Some considerations might include:
Tamper-evident designs have been a feature of letters since ancient times, often using wax, clay, or metal seals to signify that the letter had not been opened since it was written.
Similar practices continue today, [2] from examples such as envelopes to carefully designed packaging for payslips. In modern contract law, it is common to see each page of a contract individually initialled and numbered, so that any addition or removal of pages can be detected. Meanwhile, most checks have a variety of features to defeat both tampering and duplication (these are often listed on the back of the check).
Technicians at the National Security Agency developed anti-tamper holograph and prism labels that are difficult to duplicate. [3]
Tamper-evident design is perhaps most visible in the process of product packaging and labeling, where it can be vital to know that the product has not been altered since it left the manufacturer. [4] [5]
Cans of baby food were among the first high-profile cases, where manufacturers were extorted by persons claiming to have added various poisons to baby food and replaced them on supermarket shelves. The amount of stock which needed to be destroyed (because it was impossible to tell if a given item had been tampered with), and the threat of public fear, meant that tamper-evident design principles had the potential to save a lot of money in the future.
Jars of food items soon started appearing with a lid with a metal bubble in the center, commonly known as a "safety button", pulled down by vacuum in the top of the container, which—like the lid of a Mason jar—popped out if the jar had ever been opened and stayed flat if the jar was in pristine condition. These lids would also pop out if the jar was contaminated by potentially dangerous gas-producing bacteria. Customers were advised to never buy a product with a popped lid. In addition to the visible flat "button", an intact lid makes an audible "pop" when opened.
Newer jars of food tend to come with a plastic wrap around the edge of the lid, which is removed when opening, although the springy-cap designs are still in common use.
Tamper-evident packaging also extends to protect stores; there are some scale labels for meats and deli products that will tear if removed.
The 1982 Chicago Tylenol murders involved over-the-counter medications. Due to FDA regulations, many manufacturers of food and medicine (as well as other products) now use induction sealing and other special means to help provide evidence of tampering. Break-away components which cannot be reattached are useful. Custom seals, security tapes, labels, RFID tags, etc. are sometimes added.
The current epidemic of opioid abuse and drug abuse has led to a search for tamper-evident strategies to protect central vascular lines. Drug users who shoot drugs into their veins often acquire infections of the heart valves (endocarditis), liver, bones, lungs, and other organs. Treatment of these infections requires several weeks of intravenous antibiotics. During the treatment period, these patients can use the central intravenous line or peripherally inserted central line (PICC) to inject narcotics or other illicit drugs. Evidence exists that applying a tamper-evident device to the central line can deter illicit use of the line.
Security packaging is needed to contain evidence of crimes. Items must be kept in an unaltered state until they are submitted in a legal proceeding.
Packaging that tears open raggedly or otherwise cannot readily be resealed is sometimes used to help indicate tampering.
Often, multiple layers or redundant indicators are used because no single layer or device is "tamper-proof". Consideration should be given to unique custom indicators (which should be changed regularly because these are subject to counterfeiting).
People who open secure packaging can look out for signs of tampering, both at the primary means of entrance and at secondary or "back door" locations on a package.
In financial terms, tamper-evident design overlaps a lot with anti-forgery techniques, as ways to detect monetary tokens which are not what they seem.
Postage stamps, for example, may contain a layer of ultraviolet-reflective ink which changes state under pressure. The impact from a postmarking machine then leaves a UV-visible mark as well as an ink mark which identifies attempts to reuse stamps.
In a similar vein, asset-numbering labels on corporate equipment (PCs and the like) are often designed to leave an imprint of either the serial number, or the word "VOID" if the label is peeled off. However, this can easily be defeated by warming up the label using a blow dryer so it will be more flexible and forgiving to removal (and reapplication).
Road tax vignettes and price tags are often tamper-evident in the sense that they cannot be removed in one piece. This makes it difficult to move a vignette from one car to another, or to peel off a price tag from a cheaper article and reapply it to a more expensive one.
Money is tamper-evident in the sense that it should be difficult to produce a financial token without authorization, even if starting from a token of lower value. For example, forgers may attempt to clean the ink from a banknote and print the image of a higher-denomination note on it, giving them the carefully guarded "banknote paper" which is otherwise very difficult to obtain. This may be one of the reasons why many countries use banknotes of different size in ascending order of value. A British £5 banknote issued by Bank of England is much smaller than a £50 banknote, and therefore can't be used to create a £50 note.
Tamper-evident physical devices are common in sensitive computer installations. For example, network cabling can be run down transparent conduits and switches can be located in glass-fronted cabinets, allowing for any unusual device attached to the network tending to stand out in plain view.
Despite the easy availability of miniature (hardware) key loggers, tamper-evident design is not often used in personal computers. While transparent computer cases and keyboards are common, they are mainly used for the decorative effect rather than security. Many PCs do have a switch to detect opening of the case, and this provides a visual notification when the computer is next turned on that the case has recently been opened. In any case, it has long been possible to complicate the task of tampering with electronic devices by sealing them with tamper-evident tape or sealing wax. Alternatively, radio-controlled alarm-devices (which transmit a silent alarm) can be installed, or cases can be glued shut in such a manner that tampering attempts will distort or fracture the casing.
Fire alarms and other emergency switches are typically non-reversible, using a piece of glass which must be broken to activate the alarm. For example, panic buttons in burglar alarm systems might require a plastic key to reset the switch.
In very much the same manner as with fire alarms, many emergency handles and levers, or handles that are not meant to be opened regularly, are enclosed in a thin metal or plastic security seal. The seal is thin, so as not to prevent the handle from being used (in due time), but only to alert maintenance/security personnel that the handle was indeed used. Many times, large sea-going shipping containers have such a metal ring or seal attached to them at the source port. After traveling at sea (and perhaps by land as well), the containers reach their destination, where each container is checked to have the seal properly in place (against a list of doublets - container/seal).
In police work, tamper-evident techniques must often be used to guard access to evidence, providing means of storing items and samples in a way which can be used to prove that they were not altered after their collection. Special tamper-evident evidence bags are available, to be used following a strict protocol. [6] Video recordings can be protected to some degree against tampering by recording a timestamp.
Security seals are commonly employed on devices such as electronic voting machines in an attempt to detect tampering. However, testing by Argonne National Laboratory and others demonstrates that some existing seals can be quickly defeated by a trained person using low-tech methods. [7] They offer ideas on countermeasures, and are exploring the promising option of "anti-evidence" seals.
To prevent gas and electricity meters from being interfered with to show lower chargeable readings, they may be sealed with a lead or plastic seal with a government marking, typically fixed to a wire that passes through part of the meter housing. The meter cannot be opened without cutting the wire or damaging the seal. [8] [9]
In cryptographic terminology, cryptographic hash functions and cryptographic signatures are used to add a tamper-evident layer of protection to document, often referred to as an electronic signature.
Hardware-encrypted full disk drives utilise tamper-evident cases, so when it is retrieved the owner can be assured that the data has not been compromised, thus preventing costly further actions such as notifying the data owners. [10]
The document, email, or file to be protected is used to generate a signed hash, a number generated from the contents of the document. Any change to the document, no matter how trivial, such as changing a single bit from a 1 to a 0, will cause it to have a different hash, which will make the signature invalid. To alter a document while purposely maintaining the same hash, assuming the hash function and the program implementing it are properly designed, is extremely difficult .
Seal may refer to any of the following:
A screw cap or closure is a common type of closure for bottles, jars, and tubes.
A bottle cap or bottle top is a closure for the top opening of a bottle. A cap is sometimes colorfully decorated with the logo of the brand of contents. Plastic caps are used for plastic bottles, while metal with plastic backing is used for glass; plastic caps are commonly made from polyethylene or polypropylene, while metal caps are usually either steel or aluminum. Plastic caps may have a pour spout. Flip-Top caps like Flapper closures provide controlled dispensing of dry products. Caps for plastic bottles are often made of a different type of plastic from the bottle.
Packaging is the science, art and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of designing, evaluating, and producing packages. Packaging can be described as a coordinated system of preparing goods for transport, warehousing, logistics, sale, and end use. Packaging contains, protects, preserves, transports, informs, and sells. In many countries it is fully integrated into government, business, institutional, industrial, and personal use.
A closure is a device used to close or seal a container such as a bottle, jug, jar, tube, or can. A closure may be a cap, cover, lid, plug, liner, or the like. The part of the container to which the closure is applied is called the finish.
A lid, also known as a cover, is part of a container, and serves as the closure or seal, usually one that completely closes the object. Lids can be placed on small containers such as tubs as well as larger lids for open-head pails and drums. Some lids have a security strip or a tamper-evident band to hold the lid on securely until opening is desired or authorized. These are usually irreversible to indicate that the container has been opened. They can be made of varying materials ranging from plastic to metal.
A blister pack is any of several types of pre-formed plastic packaging used for small consumer goods, foods, and for pharmaceuticals.
Tamperproofing, conceptually, is a methodology used to hinder, deter or detect unauthorised access to a device or circumvention of a security system. Since any device or system can be foiled by a person with sufficient knowledge, equipment, and time, the term "tamperproof" is a misnomer unless some limitations on the tampering party's resources is explicit or assumed.
Induction sealing is the process of bonding thermoplastic materials by induction heating. This involves controlled heating an electrically conducting object by electromagnetic induction, through heat generated in the object by eddy currents.
Vacuum packing is a method of packaging that removes air from the package prior to sealing. This method involves placing items in a plastic film package, removing air from inside and sealing the package. Shrink film is sometimes used to have a tight fit to the contents. The intent of vacuum packing is usually to remove oxygen from the container to extend the shelf life of foods and, with flexible package forms, to reduce the volume of the contents and package.
Package pilferage is the theft of part of the contents of a package. It may also include theft of the contents but leaving the package, perhaps resealed with bogus contents. Small packages can be pilfered from a larger package such as a shipping container. Broader and related aspects of package theft may include taking the entire package, pallet load, truck load, shoplifting, etc. The theft may take place at any point in the parcel's journey from source to destination, including theft by rogue logistics employees and customs agents in international mail scenarios.
A tamper-evident band or security ring serves as a tamper resistant or tamper evident function to a screw cap, lid, or closure. The term tamper-proof is sometimes used but is considered a misnomer given that pilfering is still technically possible.
Security seals are tamper-evident mechanisms that seal valuable material in a room, cabinet, vehicle, or other storage facility. One common use is to seal cargo in transit shipping containers in a way that provides tamper evidence and some level of rudimentary security. Such seals can help to detect theft or contamination, either accidental or deliberate. Security seals are commonly used to secure truck trailers, vessel containers, chemical drums, airline duty-free trolleys, and utility meters. Typically they are considered an inexpensive way of providing tamper evidence of intrusion into sensitive spaces.
Pharmaceutical packaging is the packages and the packaging processes for pharmaceutical preparations. It involves all of the operations from production through drug distribution channels to the end consumer.
Currency packaging includes several forms of packing cash for easy handling and counting. Many systems use standard color-coding or are marked to indicate the amount in the package.
Packaging machinery is used throughout all packaging operations, involving primary packages to distribution packs. This includes many packaging processes: fabrication, cleaning, filling, sealing, combining, labeling, overwrapping, palletizing.
A security bag is a heavy duty bag used to contain high-value products or documents or legally sensitive items. Envelopes with security features are called security envelopes as well as security bags. Cash for deposit in a bank is often placed in a special deposit bag with security features. When used to contain items related to a crime, special evidence bags are used. Authentication of signatures and chain of custody are often required.
A pull-tight seal is a disposable tamper-evident seal which restricts access to closed objects for those who do not have access. The tightening seal is needed in cases where the use of more sophisticated security measures are impossible or impractical. The seal is not established for the physical protection of the object which is sealed, but for indicating attempts to interfere.
Security tape is a type of adhesive tape used to help reduce shipping losses due to pilfering and theft. It helps reduce tampering or product adulteration. Often it is a pressure sensitive tape or label with special tamper resistant or tamper evident features. It can be used as a ‘’security seal’’ in addition to a container closure or can be used as a security label. They are sometimes used as or with authentication products and can be an anti-pilferage seal.
Evidence packaging involves the specialized packaging methods and materials used for physical evidence. Items need to be collected at a crime scene or a fire scene, forwarded to a laboratory for forensic analysis, put in secure storage, and used in a courtroom, all while maintaining the chain of custody. Items might include DNA, drugs, hair samples, body parts, blood samples, sperm, knives, vomit, firearms, bullets, fire accelerants, computers, checkbooks, etc.
