File extension is used by Pro/ENGINEER.
Contains ASCII armored private keys used for decrypting PGP (Pretty Good Privacy) encrypted files
Video container file used by SecPlayer, a video player for the GuinXell homebrew platform, which can be run on the Sony PSP; contains sequential M-JPEG video data and .MP3 data for audio; used for playing back video on GuinXell at resolutions up to 240x160 and frame rates up to 18 frames per second. SEC files can be transferred to a Sony PSP using Windows and a USB connection.
File extension is used by some applications for compressed archive file.
The .sec file extension is used as a special format of construction specification files. This is what the Army, Navy, and NASA uses to develop project specifications for construction projects using their Specsintact software.