How PGP Works

What is PGP?
PGP is an encryption program that provides cryptographic privacy and authentication for data communication, primarily used for securing emails, files, and disk partitions.

Core Functions
Encryption/Decryption - Ensures only intended recipients can read messages

Digital Signatures - Verifies sender identity and message integrity

Authentication - Confirms who sent the message

Non-repudiation - Sender cannot later deny sending the message

How It Works (The Hybrid System)
PGP cleverly combines the best of both cryptographic worlds:

Step 1: Symmetric Encryption

Your actual message is encrypted using a fast algorithm (like AES)

Uses a one-time session key

Step 2: Asymmetric Encryption

The session key is encrypted using the recipient's public key

Only their private key can decrypt it

Key Components
Keys
Public Key: Shared with everyone, used to encrypt messages to you

Private Key: Kept secret, used to decrypt messages and create signatures

Web of Trust
PGP's decentralized trust model where users:

Sign each other's public keys

Vouch for the authenticity of keys

Build trust networks instead of relying solely on Certificate Authorities

Common Uses Today
Secure Email (via tools like GnuPG, Enigmail, Mailvelope)

File Encryption

Software Distribution (verifying package integrity)

Protecting sensitive documents

Whistleblower communications