# What is Pretty Good Privacy (PGP)?

> Pretty Good Privacy (PGP) began as a named cryptographic software product for encrypting and digitally signing files and messages.

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## Content

The label PGP is now also used loosely for OpenPGP-compatible implementations. OpenPGP is the interoperable message and key format standardized by the Internet Engineering Task Force (IETF), most recently in RFC 9580.

OpenPGP commonly uses hybrid cryptography: a randomly generated session key encrypts content, then public-key methods protect that session key for recipients. It can also attach digital signatures and key information. OpenPGP is a format and protocol family rather than one algorithm, application, or universal way to decide whether a key belongs to a person.

### Key points

- **Protection goal:** Choose encryption, signing, or both according to whether confidentiality, origin authentication, integrity, or a combination is required.
- **Identity and trust:** Verify key fingerprints or other binding evidence through an appropriate channel; possession of a key or a valid signature does not establish that an asserted identity is correct.
- **Lifecycle and interoperability:** Protect private keys, plan revocation and replacement, test recipient capabilities, and constrain legacy versions, algorithms, and optional features to a documented profile.
- **Important limitation:** OpenPGP does not protect compromised endpoints or content after an authorized recipient decrypts it. Message routing, participants, timing, and some headers may remain visible, while incorrect key verification or obsolete implementations can defeat the intended assurance.

### Related terms

[Encryption](<https://yellowcube.eu/glossary/encryption/>) · [Email encryption](<https://yellowcube.eu/glossary/email-encryption/>) · [Cryptography](<https://yellowcube.eu/glossary/cryptography/>) · [Public key infrastructure (PKI)](<https://yellowcube.eu/glossary/public-key-infrastructure/>) · [Certificate management](<https://yellowcube.eu/glossary/certificate-management/>)

### Sources

[RFC 9580, OpenPGP](https://www.rfc-editor.org/info/rfc9580/) · [RFC 3156, MIME Security with OpenPGP](https://www.rfc-editor.org/info/rfc3156/) · [RFC 9787, Guidance on End-to-End Email Security](https://www.rfc-editor.org/info/rfc9787/)

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