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. When used to contain items related to a crime, special evidence bags are used. Authentication of signatures and chain of custody are often required.
Security bags or envelopes may be specially designed plastic bags, paper bags, or fabric bags. Bags or envelopes can be made to be tamper resistant (TR); to make it difficult for unauthorized entry. Often it is more important for them to be tamper-evident (TE); to indicate when an unauthorized entry has occurred. No one security feature can be considered as "tamper proof". Layers of TR and TE features, as well as the broader security systems are needed to provide better assurance of security.
Bags and envelopes are often closed by an integral pressure sensitive adhesive on the closing flap; removal of a release liner allows convenient closing of the bag. Some adhesives, pressure sensitive tapes, an labels have special security features which are designed to irreversibly indicate opening. Tamper-indicating security seals employ a variety of mechanisms for operation, each with its own advantages and disadvantages.
Documentation such as labels for certified signatures for custody and chain-of-custody labels are frequently included.
- Rosette, J L, ”Improving Tamper-Evident Packaging: Problems, Tests and Solutions", 1992
- Yam, K.L., "Encyclopedia of Packaging Technology", John Wiley & Sons, 2009, ISBN 978-0-470-08704-6