When comparing Signal vs GNU Privacy Guard, the Slant community recommends GNU Privacy Guard for most people. In the question“What are the best tools/apps/extensions to help keep my data private?” GNU Privacy Guard is ranked 1st while Signal is ranked 5th. The most important reason people chose GNU Privacy Guard is:
GPG works on OS X, Linux, and Windows with [extensive selection of wrappers](https://www.gnupg.org/related_software/frontends.html).
Ranked in these QuestionsQuestion Ranking
Pro Provides security and privacy
Signal uses an advanced end to end encryption protocol that provides privacy for every message every time.
Pro Free and open source
Signal is free and open source software, enabling anyone to verify its security by auditing the code. It's the only private messenger that uses open source, peer-reviewed cryptographic protocols to keep your messages safe.
Pro SMS/MMS support
Signal can be your default SMS/MMS text messenger. Encryption is not possible when sending SMS to your contacts, however.
Pro Recommended by Edward Snowden
Edward Snowden uses this messenger and recommends it to everyone who is concerned about his privacy.
Pro Supports encrypted group chats
Pro Message mirroring on Signal Desktop
Signal Desktop is a Chrome extension that allows you to mirror messages from your phone, including replying.
Pro Supports sharing of various different media types
Signal supports: emoji, pictures, videos, audio, contacts, any location and GIF.
Pro You can easily view all media exchanged
You can easily view all media shared in the chat without scrolling back to when it was shared.
GPG works on OS X, Linux, and Windows with extensive selection of wrappers.
Pro Multiple types of encryption algorithms
GPG supports public key cryptography (RSA EIGamal, DSA), symmetrical key algorithms (Blowfish, AES, IDEA, etc), cryptographic hash functions (RIPEMD, SHA), and compression (ZIP, ZLIB, BZIP2).
Pro Volume and individual file encryption
With GPG you can encrypt you whole volume or files individually.
Pro Supports paired keys
Allows for encrypted communication.
Pro Supports expiring signatures
GPG keys by default expire after a set amount of time. The amount can be changed and this feature can be turned off.
Pro Both CLI and GUI versions available
GPG can be installed as a command line tool, or you can choose between several different GUI frontends available for it.
Con Single device
Signal can only be registered to one mobile device at a time. But you can link Signal to Signal Desktop.
Con Unreliable notifications
Sometimes messages won't be received if the Signal app has been closed for a long time or hasn't been opened after booting the device.
Con Needs access to your phone number and contacts to work
Con If SMS/MMS imported, other apps can't read SMS
For those using Join, Pushbullet, or similar apps to send and receive SMS/MMS from web or desktop, putting your SMS in Signal somehow breaks this functionally. The dev is aware but plans to remedy the situation have not been named a priority
Con Uses message mirroring
You phone must be on and connected to the internet for Signal Desktop to work.
Con It may be hard to find a GUI frontend that suits your needs
If you decide not to use the CLI version of GPG, it may be hard to find a GPG GUI version that suits your needs simply because of the sheer number of different versions available.