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How Reliable Is AES-256 Encryption: No Hand-Waving

proxyvpn Blog · ~5 min read

All traffic inside ProxyVPN is encrypted with AES-256 — this applies to every connection, including sessions over public, unsecured Wi-Fi in a café, airport, or hotel. Let's break down what's behind this abbreviation, why it's called the "gold standard," and where the confidence in its reliability actually comes from.

What AES-256 Actually Is

AES (Advanced Encryption Standard) is a symmetric encryption algorithm: the same key is used both to encrypt data and to decrypt it. The number 256 refers to the key length in bits. The algorithm was selected in 2001 by NIST, the US National Institute of Standards and Technology, following an open international competition — the winner was the Belgian cipher Rijndael, which showed the best combination of cryptographic strength and performance among roughly fifteen candidates from different countries.

Since then, AES-256 has become the de facto standard: banks use it to protect transactions, cloud services use it to store data, and government and military agencies in a number of countries, including the US, use it to encrypt information up to the TOP SECRET classification level.

Why Brute-Forcing the Key Is Impossible

An AES-256 key is a sequence of 256 bits, which means the number of possible combinations equals 2 to the power of 256. This number is so enormous that comparisons to anything on Earth stop being useful — so it's usually compared to the scale of the universe instead: physicists estimate the number of atoms in the observable universe at around 10^80, while 2^256 works out to roughly 10^77 combinations. In other words, brute-forcing every possible key is comparable in scale to counting a significant share of all the atoms around us.

Even assuming a fantastical amount of computing power — say, every supercomputer on Earth combined, running for billions of years — going from "the one correct key theoretically exists" to "that key has been found by brute force" remains physically unachievable within any reasonable timeframe. That's exactly why real attacks on AES-256 never target brute-forcing the key directly — it's a dead end.

The vulnerabilities that occasionally make headlines about "AES being cracked" almost always relate not to the algorithm itself, but to a flawed implementation of it: weak key generation, bugs in a specific piece of software, or side-channel attacks (for example, measuring execution time). The mathematical method behind AES-256 itself has not been compromised once in more than 20 years of public analysis.

Where the VPN Tunnel Fits In

Inside ProxyVPN, AES-256 encrypts the data traveling within the secure tunnel between your device and the server. That means even if someone intercepts the raw traffic — for example, on an open Wi-Fi network without a password — all they'll see is an unreadable encrypted stream, with no way to reconstruct the original content: which pages you're opening, what you're typing into forms, or what messages you're sending.

This is a separate layer of protection on top of what the connection protocol itself already provides (VLESS over Reality, more on that in our article on bypassing blocks): one protects the connection from being blocked and recognized by your provider, the other protects the content from being intercepted and read by outsiders.

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