client-side-encryption

Zero-knowledge client-side encryption in a SvelteKit app is implemented using the Web Crypto API to perform all cryptographic operations on the client. This ensures plaintext data never leaves the browser, preventing server access to user information.

A KEK/DEK hierarchy protects user data by deriving a Key Encryption Key from a password using PBKDF2 with 600,000+ iterations, then using it to encrypt a separate Data Encryption Key. This approach ensures deterministic key generation while AES-256-GCM encrypts the actual payload.

Client-side encryption works with Cloudflare Workers, KV, and R2 by performing all encryption in the browser before transmission. SvelteKit integration uses Web Crypto-based primitives that fit into Cloudflare workflows, storing only encrypted payloads in KV and R2 storage.

AES-256-GCM and RSA-OAEP are used together for encrypting sensitive user data in the browser via the Web Crypto API. AES-256-GCM handles symmetric payload encryption while RSA-OAEP manages authentication, with non-extractable keys preventing extraction from browser memory.

Relying on Web Crypto for enterprise-grade privacy requires all cryptographic operations to execute on the client, meaning users must have modern browsers supporting the Web Crypto API. Servers only store encrypted data, so password recovery becomes impossible without the original credentials.