PGPs

PGP, or Pretty Good Privacy, is a suite of cryptographic software and a protocol for securing electronic communications. It provides confidentiality, authentication, and data integrity through a hybrid cryptosystem that uses public-key cryptography to exchange keys and symmetric-key cryptography to encrypt data. OpenPGP is the de facto standard for PGP-compatible implementations, defined in RFC 4880 and updated over time.

Developed by Phil Zimmermann in 1991, PGP became widely used for email privacy and digital signatures. Modern implementations, such as GNU Privacy Guard (GnuPG) and various commercial products, interoperate via OpenPGP. A typical workflow involves generating a public/private key pair, distributing public keys, protecting private keys with a passphrase, and sending a message by encrypting it with a session key that is itself encrypted with the recipient's public key and signed with the sender's private key.

Key management is central to PGP. Users maintain a keyring of public keys, optionally publish revocation certificates, and establish trust through signatures or a web of trust, or a centralized PKI. Key servers have historically facilitated discovery and distribution, though practices vary.

Security considerations include protecting private keys, choosing strong passphrases, and using up-to-date algorithms. While PGP remains a widely used option for personal and organizational encrypted communications, effective use depends on careful key management and verification of identities.