OpenPGP vs PGP vs GPG - What's the Difference?
PGP, OpenPGP, and GPG are related but distinct. If you've ever wondered what the difference is between these terms - and how tools like Kleopatra, Gpg4win, ProtonMail and others fit in - this guide explains it clearly.
PGP (Pretty Good Privacy) - The original encryption software created by Phil Zimmermann in 1991. It was initially distributed as freeware, then commercialized, and is now owned by Broadcom (formerly Symantec). PGP the product is proprietary software primarily for enterprise use.
OpenPGP - The open standard (defined in RFC 4880, updated in RFC 9580) derived from PGP. It specifies how key formats, message encryption, signatures, and key exchange should work. OpenPGP is maintained by the IETF and is what virtually all modern 'PGP' tools implement.
GPG (GNU Privacy Guard) - A free, open-source implementation of the OpenPGP standard by the GNU Project. GPG is what most people install when they 'install PGP.' It's a command-line tool available on Windows, macOS, and Linux.
Kleopatra - A graphical key manager that provides a user-friendly interface for GPG on Windows (via Gpg4win). Kleopatra implements OpenPGP via GPG under the hood.
Kleopatra.app - A browser-based OpenPGP tool using OpenPGP.js - a JavaScript implementation of the OpenPGP standard. It's fully compatible with keys and messages from GPG, Kleopatra desktop, ProtonMail, and any other OpenPGP tool.
In practice: when someone says 'send me your PGP key,' they mean an OpenPGP public key. Any tool - GPG, Kleopatra, ProtonMail, Kleopatra.app - can generate and use compatible keys. The names 'PGP,' 'GPG,' and 'OpenPGP' are often used interchangeably in everyday conversation.
Privacy by design
For local OpenPGP workflows, supported cryptographic operations are performed client-side using the open-source OpenPGP.js library. Plaintext content and private key material used for these local operations do not need to be uploaded to Kleopatra Neo servers. Optional Online Sync is separate: when enabled, supported vault data is encrypted client-side before encrypted vault data is uploaded for synchronization.
Frequently Asked Questions
What is the difference between PGP and OpenPGP?
PGP is the original proprietary software. OpenPGP is the open standard derived from it. Today, virtually all PGP tools implement OpenPGP.
Is GPG the same as PGP?
GPG implements the OpenPGP standard - the open version of PGP. They are compatible and the terms are often used interchangeably, though they refer to different implementations.
Does Kleopatra use OpenPGP or PGP?
Kleopatra (both the desktop app and Kleopatra.app) implements the OpenPGP standard. Keys and messages are fully compatible with GPG, ProtonMail, and other OpenPGP tools.
What is RFC 4880?
RFC 4880 is the IETF standard that defines the OpenPGP message format. It's the technical specification that ensures all OpenPGP tools are compatible with each other.