Chapter 15 Unified Threat Management for FortiOS 5.0 : Data leak prevention : Data leak prevention concepts : Fingerprint
  
Fingerprint
Fingerprint scanning allows you to create a library of files for the FortiGate unit to examine. It will create checksum fingerprints so each file can be easily identified. Then, when files appear in network traffic, the FortiGate will generate a checksum fingerprint and compare it to those in the fingerprint database. A match triggers the configured action.