What is a SIG file?
A .SIG file is a digital signature file. It acts as an electronic fingerprint. People use it to verify that a document or software package is authentic and unchanged. Many .SIG files are "detached" signatures. This means the signature lives in a separate file from the original data.
Because a .SIG file can belong to many different systems, you might not know what created it. Many are made by CryptoPro using specific cryptographic standards. Others are made by GnuPG (GPG) for secure email and file transfers. Even Epic Games Unreal Engine and Google Widevine use .SIG files to verify data integrity.
How to open SIG files?
To open a .SIG file on your computer, you need the right cryptographic software. If you are unsure what kind of signature you have, viewer.online/sig analyzes .SIG files to identify their exact format and creator software, shows which programs can open the file, and usually previews it.
Software and tools
For desktop verification, you can use CryptoPro CSP or GnuPG. On a command-line interface, developers often use commands like `gpg --verify` to read these files. If you are working with game files, the Unreal Engine manages them automatically behind the scenes.
Best practices and conversion
Never edit a .SIG file manually in a text editor. If you change a single character, the cryptographic signature will break and become useless. Sometimes you need to change how the signature is encoded (for example, from binary to text). We recommend file conversion to sensible target formats like .PEM or .CER on convert.guru.
Summary
Because .SIG files use the known certificate2 format, viewer.online/sig can safely open and display them online, eliminating compatibility problems.