"Military-grade encryption" is an overused phrase, but few understand it. What actually happens to your passwords and bank details as they travel? The answer lives in an algorithm called AES-256, which protects all ProtonVPN traffic.
Encryption is not hiding data; it turns it into ciphertext that cannot be reversed without the key. That premise explains why AES-256 is trusted by governments and banks worldwide.
1. How symmetric encryption works
Symmetric encryption uses one key for both encryption and decryption. AES (Advanced Encryption Standard) was standardized by NIST in 2001, replacing DES.
In a VPN, your device and ProtonVPN's server negotiate a session key through a key exchange, then all data is encrypted with it. Anyone intercepting the packets only sees meaningless ciphertext.
2. Why 256-bit resists brute force
A 256-bit key means 2^256 possible combinations — roughly 1.15×10^77. Exhaustively trying every key would take longer than the age of the universe, even with all global computing power.
| Key length | Combinations | Brute force |
|---|---|---|
| 128-bit | ~3.4×10³⁸ | Currently infeasible |
| 192-bit | ~6.2×10⁵⁷ | Infeasible |
| 256-bit | ~1.15×10⁷⁷ | Theoretically infeasible |
Real attack paths target implementation flaws or side channels, not brute force. That is why ProtonVPN uses thoroughly audited crypto libraries and patches regularly.
3. AES-256 vs ChaCha20
ChaCha20 is another symmetric cipher that performs better on devices without AES hardware acceleration, especially mobile. ProtonVPN offers both so users can choose by device. Security-wise both are considered adequate today; the difference is performance, not strength.
Back to the question: how does your data get locked? A 256-bit key plus a correct implementation leaves any interceptor helpless. To feel it, start with a free vpn download from ProtonVPN and let the tunnel lock every bit.
