VPN Encryption: AES-256, RSA, and Perfect Forward Secrecy

AES-256 Encryption

AES (Advanced Encryption Standard) with 256-bit keys is the gold standard of encryption. It is used by governments, militaries, and financial institutions worldwide. The 256-bit key means there are 2^256 possible combinations — more than the number of atoms in the observable universe. Brute-forcing AES-256 is mathematically impossible with current technology.

Key Exchange: RSA and Diffie-Hellman

Before encrypted communication begins, the VPN client and server must agree on encryption keys. This is done through key exchange protocols. RSA is the traditional method, while Elliptic Curve Diffie-Hellman (ECDH) is the modern replacement offering equivalent security with smaller keys and faster performance.

Perfect Forward Secrecy

Perfect Forward Secrecy (PFS) generates a unique session key for each VPN connection. Even if an attacker were to compromise the VPN server's private key, they could not decrypt past sessions because each session used a different, ephemeral key. WireGuard and modern OpenVPN configurations support PFS.

Authentication: SHA Hashing

SHA (Secure Hash Algorithm) verifies that data has not been tampered with during transmission. SHA-256 and SHA-512 are the current standards, replacing the deprecated SHA-1. HMAC (Hash-based Message Authentication Code) combines hashing with a secret key for additional security.