AES-256 Encryption Tool

About AES-256 Encryption Tool

AES (Advanced Encryption Standard) is the industry-standard symmetric encryption algorithm — the same encryption used to protect classified government data, secure HTTPS connections, and encrypt files across virtually every major operating system. 'Symmetric' means the same passphrase used to encrypt is also used to decrypt, unlike public-key systems that use separate keys for each direction.

This tool encrypts text using AES-256 in GCM mode (Galois/Counter Mode), a modern authenticated encryption mode that protects against tampering, not just eavesdropping — if the encrypted data is altered even slightly, decryption fails cleanly instead of silently returning corrupted garbage. Your passphrase is never used directly as the encryption key; it's run through PBKDF2 (250,000 iterations) first, which makes brute-forcing the passphrase itself dramatically slower for an attacker.

Every encryption operation runs entirely in your browser using the Web Crypto API — the same standardized, browser-vendor-audited cryptographic implementation used across the web platform, not a custom reimplementation. Your plaintext and passphrase are never transmitted anywhere; only you control both.

This is useful for encrypting sensitive text before storing it somewhere less trusted (a shared document, a notes app, a support ticket), sharing a secret with someone else via a separate secure channel for the passphrase, learning how authenticated encryption works hands-on, and any situation needing genuine client-side encryption without installing software.

How it works

1. Enter the text to encrypt. Any text — a message, a note, sensitive data.
2. Choose a strong passphrase. Run through PBKDF2 with 250,000 iterations to derive the actual encryption key.
3. Encrypt and share the result. Share the encrypted text and passphrase through separate channels.