Anti-tamper and security labels: how to specify the right level of protection
A secure label has one job: to make it obvious if someone has tried to remove or interfere with whatever the label is attached to. The bar moves depending on what is being protected – a sealed enclosure on a piece of regulated equipment is a different threat model to a warranty seal on a consumer product or a security label on a calibrated instrument.
This article sets out how to choose the right type of secure label for your application, and the language to use when specifying it to a manufacturer.
Three levels of security
Most security labels UK manufacturers produce sit in one of three categories. Picking the right one starts with deciding what level of evidence of tampering you need.
Level 1 - Tamper-evident (VOID labels)
The label is made from a face material engineered so that, when removed, a pattern (typically the word VOID, or a checkerboard, or a custom pattern) is left behind on the substrate. The label cannot be lifted cleanly and reapplied without leaving evidence.
Used for: warranty seals on consumer and industrial products, asset-control seals, calibration seals on instruments, basic tamper indication on packaging.
Note: a determined attacker with enough patience can sometimes peel a VOID label without triggering the pattern. For higher-stakes applications, step up a level.
Level 2 - Destructible / frangible
The face material is engineered to fracture on removal, so the label cannot be lifted in one piece. Removing it destroys it. There is no clean re-apply.
Used for: tamper-evident security labels on regulated equipment, control-loop seals, security labels tamper proof against opportunistic removal, asset seals that must not be moved between assets.
Level 3 - Tamper-evident with serialised security features
On top of a VOID or destructible base, add serialisation (typically a unique serial number, often with a 2D barcode or QR), plus additional security features – micro-text, holographic foils, security cuts, UV-reactive inks or covert features that only an inspector knows to look for.
Used for: regulated industries, defence supply chain, pharmaceutical packaging, high-value asset control. This is the category where “secure label” starts to mean something to an auditor.
How to specify a secure label
1. Decide what counts as a “tamper event”
Is it any disturbance of the seal? Is it a full removal? Is it removal-and-replacement? The threshold drives the choice of base material and adhesive.
2. Decide who has to detect it
Trained inspector, end customer, machine vision system? Visible tamper indication is enough for human inspection. Covert features (UV-reactive, micro-text) are for trained inspection only. Machine-readable serial numbers are needed where the seal is checked in software, not by eye.
3. Decide on the substrate the seal must sit on
Painted metal, polycarbonate housing, glass, anodised aluminium, textured polymer – each requires a different adhesive. A destructible label that won’t bond properly to the housing is no use to anyone.
4. Decide on the environment
Temperature, UV, humidity, cleaning regime, vibration. A secure label that fails before it has ever been tampered with is a worse outcome than no label at all.
5. Decide on the documentation
For regulated and defence work, the supplier should record the serial range, the production batch and (where applicable) chain of custody from production to delivery. Southern produces secure label runs under EN 9100 and ISO 9001 quality management, with Cyber Essentials-aligned handling of sensitive artwork and serialisation data.
Common mistakes
- Specifying a VOID label when the threat model needs destructible.
- Putting a destructible seal on a surface the adhesive can’t bond to.
- No serial range control – duplicate seals issued, no way to prove which is which.
- Visible-only tamper features in an environment where labels get scuffed in normal use (every scuff looks like tampering).
- Forgetting to consult the regulator – some sectors have specific anti-tamper requirements that constrain the design.
How Southern produces secure labels
Briefs are scoped against the threat model, not just the artwork. We confirm substrate, environment, serialisation and documentation upfront, supply a production proof for sign-off, and produce against EN 9100 and ISO 9001 quality management. For defence and regulated customers, Cyber Essentials certification covers how we handle the artwork and serialisation data behind the labels.
Next step
Send us the application, the host material, the environment and your tamper-evidence threshold. We will come back with a costed material and serialisation proposal – and, where appropriate, an NDA in advance of detailed discussion.