A SAFE file is an encrypted file created by SIGLock, a file encryption application for Windows used to securely store and transfer files. It contains an encrypted version of a file, such as a .PDF or .XLSX file, that can only be decrypted by the SIGLock program. SAFE files also contain locking and unlocking data such as which users can open the file, where they can open it, and when they can open it.

To lock a file, therefore creating a SAFE file: Select File → Select File(s) to Lock, navigate to your file, and click Open. Specify unlocking conditions, click Lock (you can also choose Lock and Send to send to other persons). Name the file, choose the save location, click Save, and click OK. Your file's extension (.DOCX, .PPTX, etc.) is now replaced with the SAFE extension. You can also right-click the file you want to secure and select Create a SigLock File to begin the locking process. To unlock a SAFE file, select File → Select File to Unlock, select your file, click Open, and enter your password. You can also right-click the file you want to secure and select Open with SigLock and enter your password. NOTE: Before the SAFE file extension, SIGLock used the .SGZ extension for locked files. The SIGLock program is no longer developed.