Build an End-to-End Encrypted File Sharing Web App
Design a secure file-sharing platform where data is encrypted in the browser before upload, stored in ciphertext form, and decrypted only on the recipient’s device — ensuring total confidentiality.Traditional file-sharing apps may encrypt data during transit but store it unencrypted on the server. End-to-end encryption ensures that even the server can’t access the file contents, providing true privacy for sensitive data transfers.
The system ensures that only the sender and recipient can decrypt the file. All encryption is handled on the client side using cryptographic libraries, and shared links contain decryption keys or passphrases securely transmitted to authorized users only.
Client-Side AES or RSA Encryption
Encrypt files directly in the browser before upload using Web Crypto API or libraries like crypto-js.
Secure Upload & Storage
Store only encrypted file blobs on the backend with zero knowledge of file contents.
Private File Sharing Links
Generate one-time download links with embedded decryption keys or access tokens.
Optional Expiry & Download Limits
Let users set expiry time, max downloads, and auto-delete options for shared files.
When a file is selected, the client-side app encrypts it using AES or RSA before uploading it to the server. The server stores only the encrypted file. The recipient gets a shareable link containing a decryption key or is prompted for a secret passphrase to decrypt the file upon download.
- User uploads file → file is encrypted in browser → uploaded securely.
- Server stores encrypted blob without knowing the original content.
- Shareable URL is generated, optionally with embedded key or separate password.
- Recipient opens the link → decrypts file in-browser → file is downloaded.
- Admins or users can control expiration, max downloads, or file retention duration.
Frontend Encryption
Web Crypto API, crypto-js, or libsodium.js for AES/GCM encryption and key handling.
Backend Storage
Node.js/Express, Django, or Flask with S3/Cloudinary or local storage for encrypted files.
Security Enhancements
Add OTP/email authentication, auto-expiring tokens, and download rate limits.
Optional UI Libraries
React or Vue.js for drag-and-drop upload interface and secure download interface.
1. Setup Frontend File Encryptor
Build a file input form that encrypts files using AES or RSA before uploading.
2. Upload Encrypted Blob to Server
Send encrypted file + metadata (optional) to a secure backend via API.
3. Generate Secure Sharing Link
Return a sharable link containing download ID and optional decryption key.
4. Build Secure Download + Decrypt Page
Allow users to download the encrypted file and decrypt it client-side using embedded key or password.
5. Add Optional Controls
Enable link expiration, download limits, or 2FA for access restriction.
Privacy Starts With Secure Sharing
Build a fully private file sharing solution where your server never sees the content — only the sender and receiver hold the key.
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