Understanding Encryption: AES-256 vs ChaCha20
Both are used in modern VPNs, but they have very different performance characteristics. We explain when each excels and how Bit Iron chooses the right one.
VPN providers love to advertise "military-grade AES-256 encryption." It sounds impressive, and it is genuinely strong. But the second-most-common cipher in modern VPNs — ChaCha20 — is rarely mentioned in marketing materials, despite being just as secure and meaningfully faster in some environments. Here is the trade-off in plain language.
AES-256: the hardware champion
AES-256-GCM is the standard for almost everything on the modern internet. Its key strength is that virtually every desktop CPU and recent smartphone has dedicated AES hardware instructions. On these devices, AES is essentially free — encryption costs almost no CPU cycles.
The result: on laptops, desktops, and modern phones, AES-256 is often the fastest available option. It is also the most widely audited cipher in cryptographic history, with decades of public scrutiny behind it.
ChaCha20: the software champion
ChaCha20-Poly1305 was designed by Daniel Bernstein specifically for environments without AES acceleration. On older mobile devices, low-power IoT hardware, or pure-software implementations, ChaCha20 routinely outperforms AES by significant margins.
It is also genuinely secure: ChaCha20 has been adopted as a standard alongside AES by TLS 1.3 and is used by major systems including Google, Cloudflare, and the Linux kernel.
How Bit Iron chooses
Bit Iron's clients negotiate the cipher automatically based on the device profile. On hardware with AES acceleration, you get AES-256-GCM. On older or low-power devices, you get ChaCha20-Poly1305. You never need to think about this — but if you are curious, every Bit Iron client exposes the active cipher in its diagnostics panel.
Both options are equally secure for your traffic. The choice is purely about getting the best possible performance from your specific hardware.