How NourCrypt works
Zero-knowledge encryption that never sends your data anywhere.
100% client-side execution
Traditional encryption tools upload your files to a server. NourCrypt is different — all cryptographic operations run directly inside your browser's JavaScript sandbox via native window.crypto.subtle APIs.
Your files, plaintext, and secret keys never cross the internet or touch any server. You can verify this by checking your browser's Network tab.
Cryptographic standards
PBKDF2 key derivation
Your password is stretched with 600,000 iterations using SHA-256 and a 16-byte random salt to generate a 256-bit key.
AES-256-GCM cipher
Galois/Counter Mode provides both confidentiality and built-in authentication codes to detect file tampering.
Web Worker chunking
Files up to 500 MB are processed in 8 MB chunks inside non-blocking Web Workers for smooth UI.
The .nour file format
Encrypted files are saved as self-contained .nour packages:
- Magic signature (9 bytes): Identifies the format (
NOURCRYPT) - Salt & IV (28 bytes): 16-byte PBKDF2 salt + 12-byte master IV
- Encrypted metadata: AES-GCM encrypted JSON with original name, size, MIME type
- Chunk stream: 8 MB slices encrypted with unique IVs
- Custom naming: Choose a name or use automatic anonymization