Cryptography: The Pillar of Confidentiality
Cryptography is the mathematical science used to encrypt information and make it incomprehensible to prying eyes.
Symmetric cryptography uses a single secret key shared for both encryption and decryption of the text, resulting in speed.
Asymmetric cryptography uses a pair of keys: a public key for encryption and a private key for decryption.
Web Application Protocols
HTTP is the protocol at the base of the World Wide Web, but it transmits data in plain text, exposing users to interception attacks.
HTTPS resolves this weakness by wrapping HTTP sessions in an encrypted channel using TLS/SSL protocols.
FTP is the protocol dedicated to file transfer, often replaced by SFTP or FTPS to ensure credential security.
Email Protocols
Email management relies on three specialized application protocols that work in close synergy.
SMTP (Simple Mail Transfer Protocol) is responsible for sending emails from the client to the server and between different mail servers.
POP3 (Post Office Protocol v3) downloads messages from the server directly to the local machine, normally deleting them from the server.
IMAP (Internet Message Access Protocol) synchronizes emails, keeping them on the server, allowing management from multiple devices.
For privacy reasons, today these protocols are used almost exclusively with SSL/TLS encryption (SMTPS, IMAPS, POP3S).
Conclusions
The progressive adoption of strong cryptography in every application protocol has made the Internet an infinitely safer environment.