Difference between GPG and PGP
Summary
PGP is proprietary encryption software created in 1991, while GPG is its free, open-source alternative. OpenPGP and LibrePGP are the standards that define how these tools interoperate.
Introduction #
When you look into email encryption or file signing, you will quickly encounter the terms PGP, GPG, OpenPGP, and LibrePGP. These names are related but refer to different things: some are software applications, others are standards. This article explains what each one is, how they differ, and how they relate to each other.
Pretty Good Privacy (PGP) #
Pretty Good Privacy (PGP) is an encryption program created by Phil Zimmermann in 1991. It was designed for encrypting and decrypting emails, files, and disk volumes using a combination of symmetric-key cryptography and public-key cryptography.
PGP was one of the first widely available programs that brought strong cryptographic tools to everyday users. After its initial release, PGP went through several ownership changes. Phil Zimmermann co-founded PGP Corporation in 2002, which Symantec acquired in 2010. Broadcom later acquired Symantec’s enterprise security division in 2019.
Today, PGP as a standalone product is no longer sold. Its technology lives on inside Broadcom’s enterprise security portfolio.
PGP advantages #
- PGP was the pioneering software that introduced public-key encryption to a broad audience.
- It supported both symmetric and asymmetric encryption, along with digital signatures and compression.
- PGP inspired the creation of the OpenPGP standard, which remains in use today.
PGP disadvantages #
- PGP is proprietary software. You cannot inspect or audit the source code.
- The standalone product is discontinued. You can only access PGP technology through Broadcom’s enterprise offerings.
- Licensing costs make PGP impractical for individual users or small organizations.
- Because the source code is closed, you have to trust the vendor regarding the absence of backdoors or vulnerabilities.
GnuPG (GPG) #
GNU Privacy Guard (GnuPG), commonly called GPG, is a free and open-source implementation of the OpenPGP standard. Werner Koch started the project in 1997, and the first stable version was released in 1999. The German Federal Ministry of Economics and Technology funded part of its early development.
GnuPG has moved to support LibrePGP rather than the latest OpenPGP (RFC 9580) standard, which may affect future interoperability.
GPG provides the same core functionality as PGP: encryption, decryption, and digital signatures. It is included in most Linux distributions by default and is available for Windows and macOS as well.
You can use GPG from the command line. For example, to encrypt a file:
gpg --encrypt --recipient user@example.com file.txt
To decrypt it:
gpg --decrypt file.txt.gpg
GPG advantages #
- GPG is free and open source, licensed under the GNU General Public License (GPL) version 3 or later.
- The source code is publicly available. Anyone can audit it for security vulnerabilities.
- GPG runs on Linux, macOS, Windows, and several other operating systems.
- It is actively maintained and receives regular updates.
- GPG integrates with many email clients and other software through plugins and libraries.
- It is the most widely used OpenPGP implementation.
GPG disadvantages #
- The command-line interface can be difficult for users who are not comfortable with a terminal.
- Key management (generating, distributing, revoking, and trusting keys) has a steep learning curve.
- Graphical front-ends for GPG exist, but they vary in quality and platform support.
- GnuPG has moved to support LibrePGP rather than the latest OpenPGP (RFC 9580) standard, which may affect future interoperability.
OpenPGP #
OpenPGP is not software. It is an open standard that defines the message formats, encryption algorithms, and procedures for encrypted communication. Phil Zimmermann and the Internet Engineering Task Force (IETF) published the original specification as Request for Comments (RFC) 2440 in 1998, based on PGP version 5. This was updated by RFC 4880 in 2007, and the latest version is RFC 9580, published in 2024.
Any developer or organization can implement the OpenPGP standard in their own software. This is what makes tools like GPG, OpenPGP.js, and Sequoia PGP possible.
OpenPGP advantages #
- OpenPGP is a vendor-neutral standard. No single company controls it.
- Multiple independent implementations exist, which promotes competition and choice.
- The IETF review process means the standard undergoes public scrutiny.
- RFC 9580 introduces modern cryptographic algorithms, including Authenticated Encryption with Associated Data (AEAD) and updated key derivation methods.
- OpenPGP enables interoperability between different software tools.
OpenPGP disadvantages #
- The standard has grown complex over decades of revisions, making new implementations difficult to write correctly.
- The transition from RFC 4880 to RFC 9580 has caused a split in the community (see LibrePGP below).
- Backward compatibility requirements limit how quickly older, weaker algorithms can be removed.
- OpenPGP does not provide forward secrecy by default, unlike protocols such as Signal.
LibrePGP #
LibrePGP is a specification that emerged from disagreements within the OpenPGP community during the development of RFC 9580. The GnuPG project and some other parties objected to certain design decisions in the new OpenPGP standard, particularly around AEAD mechanisms and version 6 key formats. In response, they created LibrePGP as a separate specification based on RFC 4880.
LibrePGP is maintained primarily by the GnuPG project. It aims to provide a more conservative update path that preserves compatibility with existing deployments.
LibrePGP advantages #
- LibrePGP prioritizes backward compatibility with the large base of existing GnuPG and RFC 4880 installations.
- It takes a more conservative approach to introducing new cryptographic mechanisms.
- Because GnuPG supports LibrePGP, a significant user base already works with this specification.
LibrePGP disadvantages #
- LibrePGP is not an IETF-endorsed standard. It lacks the formal review process that OpenPGP has.
- The specification is maintained by a smaller group compared to the OpenPGP working group.
- The existence of two competing specifications (OpenPGP and LibrePGP) fragments the ecosystem and creates confusion.
- Implementations following LibrePGP may not be fully compatible with those following RFC 9580.
Comparison table #
| PGP | GPG | OpenPGP | LibrePGP | |
|---|---|---|---|---|
| Type | Software | Software | Standard | Standard |
| First release | 1991 | 1999 | 1998 (RFC 2440) | 2023 |
| License | Proprietary | GPL-3.0-or-later | n/a | n/a |
| Maintainer | Broadcom | Werner Koch / GnuPG project | IETF OpenPGP working group | GnuPG project |
| Cost | Paid (enterprise) | Free | n/a | n/a |
| Interoperability | OpenPGP-compatible | OpenPGP / LibrePGP | Vendor-neutral standard | Based on RFC 4880 |
| Platforms | Windows, macOS | Linux, macOS, Windows, BSD | n/a | n/a |
FAQ's #
Most common questions and brief, easy-to-understand answers on the topic:
Is GPG the same as PGP?
No. PGP is proprietary software originally created by Phil Zimmermann. GPG (GnuPG) is a free, open-source implementation that follows the OpenPGP standard. Both provide encryption and digital signatures, but they differ in licensing, cost, and source code availability.
Can GPG and PGP exchange encrypted messages?
Yes. Because both GPG and PGP implement the OpenPGP standard (defined in RFC 4880), they are interoperable. A message encrypted with GPG can be decrypted with PGP and vice versa.
Is GPG free to use?
Yes. GnuPG (GPG) is free and open-source software released under the GNU GPL. You can download, use, and distribute it at no cost.
Is PGP still available?
The original standalone PGP product is no longer sold. Broadcom (formerly Symantec) acquired PGP Corporation in 2010 and integrated PGP technology into its enterprise security products.
What is OpenPGP?
OpenPGP is an open standard that defines the format and protocols for public-key encryption, digital signatures, and key management. It is defined in RFC 4880 and maintained by the IETF. Both PGP and GPG implement this standard.
Which should you use: PGP or GPG?
For most users, GPG (GnuPG) is the practical choice. It is free, actively maintained, available on all major operating systems, and fully compatible with PGP through the shared OpenPGP standard. Commercial PGP products offer additional enterprise features and vendor support.
What is the difference between OpenPGP and LibrePGP?
OpenPGP is the IETF standard defined in RFC 9580, maintained by the OpenPGP working group. LibrePGP is a separate specification forked from RFC 4880, maintained by the GnuPG project, which disagreed with some decisions in the newer OpenPGP draft.
Do I need to understand the difference between PGP and GPG to encrypt files or emails?
Not in day-to-day use. Most email clients and tools that support email encryption will use GPG under the hood and abstract away the details. Understanding the distinction matters mainly when evaluating software, reading security documentation, or troubleshooting compatibility issues.
Further readings #
Sources and recommended, further resources on the topic:
- GnuPG: Official website
- OpenPGP: Official website
- IETF: RFC 9580: OpenPGP
- IETF: RFC 4880: OpenPGP Message Format
- LibrePGP: Official website
- Wikipedia: Pretty Good Privacy
- Wikipedia: GNU Privacy Guard
- Wikipedia: OpenPGP
- GNU Privacy Guard (GPG) Cheat Sheet
Author
Jonas Jared Jacek (J15k)
Jonas works as project manager, web designer, and web developer since 2001. On top of that, he is a Linux system administrator with a broad interest in things related to programming, architecture, and design. See: https://www.j15k.com/License
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