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Signing & Verifying Files

GpgFrontend extends its utility from handling text-based operations to facilitating file operations with ease and security. The principle behind signing and verifying files mirrors that of text, leveraging the robust framework of digital signatures. However, a significant distinction lies in the nature of the input and output for file operations, which can be binary, accommodating a wider range of file types beyond simple text documents.

When signing a file using GpgFrontend, the software utilizes the private key of the user to create a digital signature. This process begins by computing a hash of the file’s contents, regardless of whether the file is a document, image, executable, or any other binary format. This hash serves as a compact representation of the file’s data. Subsequently, the hash is encrypted with the user’s private key, producing a digital signature unique to both the file and the key used. The resulting signature can either be attached to the file or stored separately, depending on the user’s preference and the requirements of the application.

Verifying a signed file with GpgFrontend involves the corresponding public key of the private key that was used for signing. The verification process decrypts the digital signature using this public key to extract the original hash value that was generated during the signing. Simultaneously, the software computes a new hash from the file that is purported to be authentic. By comparing these two hash values, GpgFrontend can determine if the file has been altered after it was signed. If the hashes match, it confirms the file’s integrity and authenticity, assuring the recipient of its untampered state and the signer’s identity.

This binary capability of file operations in GpgFrontend not only broadens the scope of digital signatures to encompass a variety of file types but also ensures that the integrity and authenticity verification process is not limited to text-based data. It provides a critical layer of security in digital communications, where files of all kinds are shared and exchanged with the expectation of privacy and trust.

The application of digital signatures to files through tools like GpgFrontend is especially relevant in scenarios where the authenticity of the file source and the integrity of its contents are paramount. This includes software distribution, where verifying the source and integrity of software packages is crucial to prevent malware distribution; document sharing in legal and financial contexts, where tampering could have serious implications; and multimedia content distribution, where copyright and ownership are significant concerns.

In summary, GpgFrontend’s support for signing and verifying files elevates the security of digital file exchanges by applying the principles of cryptography in a user-friendly manner. By accommodating binary file operations, it ensures that digital signatures are accessible and applicable across a broad spectrum of file types, reinforcing the pillars of trust and security in digital communications.

Introduction to File Extensions

For ASCII-formatted ciphertext, the filename suffix is usually “asc”, and these files can be opened directly with a text editor. However, if the ciphertext is binary, its file extension will be “sig” or “gpg”. Typically, binary ciphertext files are smaller than ASCII-formatted ones.

Prior to v2.0.4, the ciphertext files generated by GpgFrontend were all in ASCII format. But starting with v2.0.4, GpgFrontend defaults to generating binary-formatted ciphertext files. You can modify this setting in the settings.


File Browser

You can open the file browser (Ctrl/Command + B) via the top menu file option. After selecting a target directory at system navigator, you can get a new File browser tab. Using the file browser, navigate to your working directory. Then, right-click the file you wish to operate on, and select the desired operation from the pop-up menu.

File Browser

Two control buttons are located at the top of the file tab. The one on the left allows you to go up a level, and the one on the right enables you to enter or refresh the corresponding path in the input box on the left.

On the far right is a button offering useful options, such as displaying system files or hidden files.

File Browser 2


Through the right-click menu, you can rapidly sign a file. This operation will generate a file with a “sig” or “asc” suffix, which contains the signature content. In this scenario, you need to pass both this file and the original file to the other party to allow them to verify it.

Sign File


This operation requires you to select a file with a “gpg” suffix (this may be invalid for binary file ciphertext) or a file with a “sig” suffix for verification.

When selecting a file with the “sig” suffix, ensure that the source file is also present in this directory. This implies that the source file’s name is simply missing a “sig” suffix.

Verify File