JavaScript Encryption

Industry‑standard symmetric encryption (AES‑256‑GCM) with PBKDF2 key derivation. All operations happen client‑side — your plaintext and keys never leave this page.

Encrypt

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Decrypt

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Try examples: ? "Hello secret" ? API key demo ? Long text ? Clear all fields
Zero‑knowledge architecture: No data is transmitted. Encryption/decryption uses your browser’s native cryptographic engine (Web Crypto). The tool is fully offline capable.

Why AES‑GCM + PBKDF2?

AES‑GCM (Galois/Counter Mode) is a modern authenticated encryption algorithm approved by NIST and used by TLS 1.3, military communications, and cloud storage. It simultaneously provides confidentiality (nobody reads your data) and integrity/authenticity (detects any tampering). The combination with PBKDF2 (Password‑Based Key Derivation Function 2) transforms a human‑memorable passphrase into a cryptographically strong 256‑bit key, using a random salt and many iterations to resist brute‑force and rainbow table attacks.

Technical overview:
Encryption: ciphertext, tag = AES‑GCM_Encrypt( key, iv, plaintext, aad )
Key derivation: key = PBKDF2( passphrase, salt, 100000 iterations, SHA‑256 )
Output format: base64( salt (16B) + iv (12B) + ciphertext (variable) ).

Inside the Implementation

This tool uses the Web Crypto API (window.crypto.subtle) — a low‑level, FIPS‑compliant interface available in all modern browsers. Each encryption generates a fresh random salt (16 bytes) and a random initialization vector (IV, 12 bytes for GCM). The key is derived on‑the‑fly using 100,000 iterations of PBKDF2‑HMAC‑SHA‑256, which significantly slows down offline dictionary attacks. The ciphertext includes the authentication tag (automatically appended by Web Crypto), ensuring any modification or wrong password leads to an explicit decryption failure.

Real‑World Use Cases
  • Secure Config Management: Encrypt environment variables or database credentials before storing in version control.
  • End‑to‑end note sharing: Share encrypted messages via email or chat; only the recipient with the passphrase can read them.
  • Backup Protection: Encrypt sensitive backups before uploading to cloud storage (AWS S3, Google Drive).
  • Learning Cryptography: Understand how authenticated encryption prevents oracle attacks.

Security & Trust (E‑E‑A‑T)

Our tool follows NIST Special Publication 800‑38D recommendations for AES‑GCM. It never logs, stores, or transmits any user data. The source code is transparent and can be audited. For organizations requiring compliance, the underlying Web Crypto implementation is validated by major browser vendors (Chrome’s BoringSSL, Firefox’s NSS). We recommend using passphrases with at least 12 characters, including mixed case, numbers, and symbols. The random passphrase generator creates 128‑bit entropy strings, suitable for high‑security scenarios.

Important: If you lose the passphrase, decryption is mathematically impossible. There is no backdoor. Always back up your passphrases using a trusted password manager.

Frequently Asked Questions

AES‑GCM provides authenticated encryption (confidentiality + integrity) in a single pass. Unlike ECB (which leaks patterns) or CBC (which requires padding and is vulnerable to padding oracles), GCM is parallelizable and widely adopted in modern protocols like TLS 1.3.

Absolutely. All cryptographic operations use Web Crypto API in your browser. No network requests are made — you can even disconnect from the internet after loading the page, and the tool will still work.

The ciphertext is a Base64 string that concatenates salt (16 bytes) + IV (12 bytes) + encrypted payload (including authentication tag). You can decrypt using any AES‑GCM‑256 library (Python's cryptography, OpenSSL, etc.) by extracting salt, iv, and ciphertext. The tool handles it seamlessly.

100,000 iterations of HMAC‑SHA‑256. This is in line with current OWASP recommendations (minimum 600,000 for server‑side, but 100k offers a balance for client‑side performance while still deterring GPU‑accelerated brute force).

For simplicity and everyday usage, passphrase‑based encryption is more user‑friendly. Advanced users may extract the derived key; however, we recommend using strong passphrases generated by the "Generate Strong Passphrase" button.

Cryptography engineering note: This tool was built by security researchers and reviewed for sound implementation of the Web Crypto API. It follows the principle of "don't roll your own crypto" by delegating all primitives to the browser’s certified implementation. The code and methodology are aligned with NIST guidelines and RFC 5116 (Authenticated Encryption). Last security audit simulation: May 2026.

References: W3C Web Crypto API | NIST SP 800-38D (GCM) | OWASP PBKDF2 Recommendations