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Symmetric vs. Asymmetric Encryption

Encryption divides into two broad families. Symmetric encryption uses the same key for both encrypting and decrypting data. Algorithms like AES-256 are fast enough for bulk data encryption — disk encryption, VPN tunnels, and database-at-rest protection all use symmetric ciphers. The challenge is securely exchanging the shared key between parties who have never met.

Asymmetric encryption uses a mathematically linked key pair: a public key (shareable with anyone) and a private key (kept secret). Data encrypted with the public key can only be decrypted with the private key. RSA and elliptic-curve algorithms (ECDSA, X25519) are common. Asymmetric encryption is computationally slower than symmetric, so real-world systems use it only to negotiate and exchange symmetric session keys.

How TLS Combines Both

SSL/TLSSecure Sockets Layer / Transport Layer Security. Cryptographic protocols that provide encrypted, authenticated communication over a network. SSL is deprecated; modern implementations use TLS 1.2 or TLS 1.3. exemplifies the hybrid approach: asymmetric key exchange (using the server's SSL/TLS CertificateA digital document that binds a cryptographic key pair to an organization or domain, enabling encrypted HTTPS connections. Issued by Certificate Authorities (CAs) like Let's Encrypt, it proves a website's identity to browsers. public key or Diffie-Hellman) establishes a shared session key, then all subsequent data flows under fast symmetric encryption. This gives you the key-exchange security of asymmetric cryptography with the performance of symmetric ciphers.

Encryption in Transit vs. At Rest

Encryption in transit protects data moving across networks — HTTPSHTTP Secure. The encrypted version of HTTP that uses TLS to protect data in transit between a browser and a web server. Identified by the padlock icon in browsers and the https:// URL scheme., TLS-wrapped database connections, VPN tunnels. Encryption at rest protects stored data — encrypted disk volumes, database field encryption, encrypted backups. Both are necessary; an encrypted connection to a server that stores data in plaintext provides only partial protection. Use SSL Certificate Checker to verify that a website's TLS implementation is correctly encrypting traffic in transit.