// glossary / openpgp

OpenPGP.

The open standard for PGP-style encryption and signing — defined in RFC 4880 (the v4 key format from 2007) and RFC 9580 (the v6 key format from 2024). It's the interoperability contract between every PGP-compatible tool: GnuPG, GPG Suite, OpenKeychain, Mailvelope, FlowCrypt, PGPony, and others all produce and consume OpenPGP-format messages.

// definition

OpenPGP is the IETF standard that specifies the message format, algorithms, and protocols used by PGP-compatible cryptographic software. RFC 4880 (2007) defines v4 keys; RFC 9580 (2024) defines v6 keys with modern AEAD constructions and updated algorithms.

What it is.

Before OpenPGP, "PGP" referred specifically to Phil Zimmermann's original program from 1991 and its commercial successors. The codebase was proprietary; interoperability was inconsistent. In the late 1990s the IETF chartered the OpenPGP working group to publish an open standard derived from the PGP message format, which everyone could implement freely.

The result was a series of RFCs:

RFC 2440 (1998) — first OpenPGP standard.
RFC 4880 (2007) — the v4 key format used by GnuPG, GPG Suite, OpenKeychain, and PGPony today. Still the dominant format in 2026.
RFC 9580 (2024) — the v6 key format with modern AEAD encryption, SHA-256-based fingerprints, and updated algorithm selections. Adoption is gradual: tools like Sequoia and PGPony support it fully, while some others (notably current GnuPG) have not yet implemented it. More on OpenPGP v6 →

OpenPGP specifies everything needed for interop: key format (packets, structure, encoding), message format (encrypted, signed, clearsigned), supported algorithms (RSA, ECC, AES, hashes), and the wire format used to serialize all of these.

Why it matters.

OpenPGP is what makes "your PGP key works in every PGP tool" true. Generate a key in PGPony, export it, import into GnuPG on Linux, use it from GPG Suite on macOS — same key, same fingerprint, identical behavior everywhere. The portability is the whole point.

It also keeps the ecosystem competitive. Anyone can implement OpenPGP — PGPony is the new entrant in a field that includes 30+ years of GnuPG development. As long as the output is RFC-compliant, the implementations interoperate. No platform lock-in, no vendor-specific format.

The two key-format versions matter for compatibility decisions: v4 is universal in 2026, v6 is the future. PGPony supports both fully — it generates and uses v4 keys (universally interoperable) and OpenPGP v6 keys (modern crypto, Sequoia-class interop), with a picker so you choose per key. Pick v6 for the strongest guarantees, or v4 when you need to exchange with GnuPG users today.

// RFC references

RFC 4880 (2007): OpenPGP Message Format (v4 keys) https://www.rfc-editor.org/rfc/rfc4880 RFC 9580 (2024): OpenPGP (v6 keys, modern algorithms) https://www.rfc-editor.org/rfc/rfc9580 Older history: RFC 2440 (1998): Original OpenPGP standard RFC 3156 (2001): MIME Security with OpenPGP

// in PGPony PGPony's Settings → About surfaces the OpenPGP Standard version (RFC 4880 + 9580) so you know what the app supports. The Generate Key screen offers a v6 / v4 picker — v6 produces an Ed25519 primary with an Ed25519 signing subkey and an X25519 encryption subkey, verified against Sequoia and the RFC 9580 Appendix A test vectors; v4 remains available for GnuPG compatibility.

Related terms

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