In Part 1 of this article, we gave you a little bit of a teaser as to what security seals are and how they can be used. In this article we’ll get a little more specific.


Types of Security Seals

A security seal is a tamper indicating device (TID) designed to leave noticeable evidence of unauthorized access or entry. Think of the footprint example in Part 1 of this article. Seals are not meant to restrict access, instead they are meant to record the fact that unauthorized access has taken place.

There are several types of seals. The most common types have been described below.

mechanical seal: a seal that does not rely on batteries or electrical power to monitor for tampering. A plastic security seal is a perfect example of this type of seal. The seal itself is not meant to prevent access but rather is meant to signal that access has been made if the seal is broken.

electronic seal:  an electronic seal uses batteries or electrical power to monitor for tampering.  Electronic seals are usually more expensive than mechanical seals, but are often reusable.

transponder seal:  a seal is not to be confused with an electronic seal.  The seal is briefly powered up by, or for the seal reader to check if tampering has occurred.  An example of this type of seal is an RFID seal.

barrier seal: this is a single security device that works both as a lock and a seal.  Despite its multiple applications, barrier seals are usually a compromise of the two and as a result are not as effective as having a lock and a seal.

Trap seal: a trap seal will indicate tampering covertly allowing for the administrator to monitor for tampering without “tipping-off” the attacker.

Other Terminology Related to Seals

Seal reader or seal verifier:  these devices may be used in combination with mechanical, electronic and transponder seals.  The readers check the seal for evidence of tampering.

inspecting a seal:  checking the seal for evidence of tampering.

defeating a seal: defeating a seal is the act of successfully tampering with a seal without being detected.

attacking a seal: performing actions that attempt to defeat a seals tamper indication properties.

backdoor attack: an attack where a person modifies the seal or the seal location prior to use to make it easier to defeat the seal at a later time.


In Part 3 of this article, we will discuss some misconceptions associated with security seals and why security seals are often better than locks when used for certain applications.


Start Protecting Your Stuff: Part 1 – Part 2 – Part 3