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 3rd while Signal is ranked 4th. 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).
Specs
Ranked in these QuestionsQuestion Ranking
Pros
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 Supports encrypted group chats
Pro Has a desktop app
Signal Desktop can be used on multiple devices and has most features of the Android version, although it still requires you to register with your phone.
Pro Supports sharing of various different media types
Signal supports: emoji, pictures, videos, audio, contacts, any location and GIF.
Pro Note to Self feature
Allows you to "send: messages to yourself and sync to desktop so you can use Signal as a kind of encrypted Pushbullet alternative
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.
Pro Annonymous Sender (Encrypted)
The sender credentials can be encrypted with the rest of the message, leaving only the recipient address readable by the Signal server. Even if Signal wanted they couldn't see who is talking with who by this mean.
Pro Works everywhere in every country
Unlike most messenger apps, Signal works reliably in all countries by securely circumventing internet censorship.
Pro Recommended by Edward Snowden
Edward Snowden uses this messenger and recommends it to everyone who is concerned about his privacy.
Pro Cross-platform
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 Excellent but...
Open source (the free version of openPgp), other similar products are offered for other platforms (Gpg4win for Windows for example). It is the most secure way to send emails today, close to military encryption. Some negative points: not all mail clients support it and when a key is not only on your hard disk but also on a server (pgp.mit.edu for example), it is complicated to remove it.
Last positive point: it can also be used other than for emails, to encrypt and sign documents. Bitcoin releases are signed with the GPG keys of the developers ;)
Pro Supports paired keys
Allows for encrypted communication.
Pro Volume and individual file encryption
With GPG you can encrypt you whole volume or files individually.
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.
Pro Open-source and battle-tested
GPG is the oldest and most reliable encryption software available.
Cons
Con Needs access to your phone number and contacts to work
Con Single device
Signal can only be registered to one mobile device at a time. But you can link Signal to Signal Desktop.
Con Servers hosted in the US
A security risk due to National Security letters, which require giving up data to the US state, and making it illegal to disclose that.
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 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.