Encrypt text or files locally with AES-256-GCM — your data never leaves your browser.
Both are authenticated encryption
AES-GCM and ChaCha20-Poly1305 are AEAD constructions: they encrypt data and authenticate it in one operation, so tampering is detected. Both are used in TLS 1.3 and modern protocols.
AES-GCM is standardized by NIST SP 800-38D; ChaCha20-Poly1305 is standardized by RFC 8439. Neither has a known practical break in 2026.
AES-GCM vs ChaCha20-Poly1305: which should you use?
Choose AES-256-GCM when the CPU has AES-NI or ARM crypto extensions — most current servers, laptops and phones do, and it is the AEAD the Web Crypto API exposes in browsers. Choose ChaCha20-Poly1305 on hardware without AES acceleration, or when you want constant-time software performance. Both are AEAD; neither has a practical break.
| Property | AES-256-GCM | ChaCha20-Poly1305 |
|---|---|---|
| Standard | NIST SP 800-38D | RFC 8439 |
| Hardware acceleration | Excellent with AES-NI | Not required |
| Software speed | Moderate without AES-NI | Fast, constant-time |
| Nonce size | 96 bits typical | 96 bits |
| Side-channel risk | GHASH without hardware | Low by design |
| Mobile performance | Fast on ARMv8 phones (AES instructions), slow on older ARM CPUs | Fast on every phone, including older ARM CPUs |
| Best for | Servers, browsers, TLS 1.3 defaults | CPUs without AES support, embedded systems, software-only stacks |
AES-GCM: fast when hardware helps
On CPUs with AES-NI or ARM Crypto Extensions, AES-GCM runs extremely fast because the block cipher is executed in hardware. That is why it is the default in browsers, servers, and TLS.
Its weak points are subtle: reusing a nonce with the same key is catastrophic, truncated tags weaken security, and on devices without hardware support, GHASH can be slow or side-channel sensitive.
ChaCha20-Poly1305: fast in pure software
ChaCha20 is an ARX cipher (add, rotate, xor) designed to be fast and constant-time in software, with no special hardware needed. Poly1305 authenticates the ciphertext.
It shines on mobile devices, embedded systems, and CPUs without AES-NI, and it avoids the GHASH side-channel pitfalls of GCM on such hardware.
What decides it
- Browsers and servers with AES-NI: AES-GCM is fast and battle-tested
- Mobile, embedded, or CPUs without crypto extensions: ChaCha20-Poly1305 is often the better choice
- TLS 1.3: let the stack negotiate; both are strong
- This site uses AES-256-GCM with PBKDF2 via the Web Crypto API, so encryption works natively in every modern browser
Warning: Whichever cipher you use, never reuse a nonce with the same key. A repeated nonce destroys both confidentiality and authentication for AES-GCM and ChaCha20-Poly1305 alike.
FAQ
Q.Is ChaCha20 more secure than AES?
A.Both are considered secure. ChaCha20 offers better software performance and simpler side-channel resistance; AES offers mature hardware acceleration. Choose by platform, not by perceived strength.
Q.Can I use ChaCha20-Poly1305 in the browser?
A.The Web Crypto API does not expose ChaCha20-Poly1305 in all browsers, which is why browser tools typically use AES-GCM. Native platforms can use both via libraries such as libsodium.
Q.Why does the ZeyroVault encryptor use AES-GCM?
A.AES-256-GCM is supported by the Web Crypto API in every modern browser, hardware-accelerated, and standardized. It keeps encryption native, fast, and zero-knowledge without extra libraries.
References
- RFC 8439 – ChaCha20 and Poly1305 for IETF Protocols: https://www.rfc-editor.org/rfc/rfc8439
- NIST SP 800-38D – Galois/Counter Mode (GCM): https://csrc.nist.gov/pubs/sp/800/38/d/final
Encrypt something locally
AES-256-GCM in your browser, no upload, no account.
Choose by platform
On servers and browsers with AES-NI, AES-GCM is fast and boring in the good way. On phones, embedded devices, and CPUs without crypto extensions, ChaCha20-Poly1305 usually wins.
Either way, never reuse a nonce under the same key. You can exercise AES-256-GCM locally with the AES-256-GCM Encryptor.
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