What Is End-to-End Encrypted File Sharing? A Beginner's Guide

You've probably heard the term "end-to-end encryption" (E2E or E2EE). It's a security feature WhatsApp and Signal advertise, but many people are unsure what it actually means. This guide explains what end-to-end encryption is and why it matters for file sharing.

Regular Encryption vs End-to-End Encryption

Regular Encryption (TLS/HTTPS)

Most websites are encrypted via HTTPS. The flow looks like:

You → [Encrypt] → Server → [Decrypt] → [Re-encrypt] → Recipient

Data is encrypted in transit, but the server can decrypt and read it. Email, Google Drive, and most cloud services work this way.

End-to-End Encryption (E2EE)

End-to-end encryption is different:

You → [Encrypt] → Server → Recipient → [Decrypt]

The server can never decrypt the data. Only the sender and recipient can see the original.

Why End-to-End Encryption Matters

1. Safe Even If the Server Is Hacked

If the server is breached, attackers only get encrypted data. Without the key, it's meaningless bytes.

2. Even the Service Provider Can't Read It

Companies like Google or Microsoft technically have access to data on their servers. With E2E encryption, even they can't read your files.

3. Protected from Government/Law Enforcement Requests

If a company is asked to hand over data, all they can give is encrypted bytes.

4. Prevents Insider Access

Stops curious or malicious employees from looking at user data.

What E2E Encryption Means for File Sharing

Regular file sharing (Google Drive, Dropbox, etc.):

Item	Possible?
Server decrypts files	✅ Yes
Provider can read files	✅ Yes
Originals exposed if hacked	✅ Risk
Can be handed to law enforcement	✅ Yes

End-to-end encrypted file sharing (LOCK.PUB, etc.):

Item	Possible?
Server decrypts files	❌ No
Provider can read files	❌ No
Originals exposed if hacked	❌ Safe
Can be handed to law enforcement	❌ Encrypted bytes only

How E2E Encryption Works

Take LOCK.PUB file sharing as an example:

1. Upload: A key is derived from your password, and the file is AES-encrypted with that key
2. Storage: Only the encrypted file is saved on the server. The password and key are never stored
3. Download: When the recipient enters the password, a temporary download URL and key are issued
4. Decryption: The file is decrypted in the recipient's browser. The server never sees the decrypted file

Caveats of E2E Encryption

End-to-end encryption is powerful but has limitations:

1. No Recovery for Forgotten Passwords

The server doesn't know your password, so if you forget it, the file is permanently inaccessible. This isn't a flaw — it's proof of true E2E encryption.

2. Weak Passwords Defeat the Purpose

Passwords like "1234" can be cracked by brute force. Use strong passwords.

3. The Recipient's Device Must Be Secure

If the recipient's computer is compromised, decrypted files can be exposed. E2E encryption only protects data in transit.

Which Services Are Actually E2E Encrypted?

Service	E2E Encrypted?
Google Drive	❌
Dropbox	❌
OneDrive	❌
WeTransfer	❌
Tresorit	✅
Sync.com	✅
LOCK.PUB (file sharing)	✅
Signal (messenger)	✅
WhatsApp (messenger)	✅

Final Thoughts

End-to-end encryption isn't just a marketing term — it's a genuinely strong security model. When sharing sensitive files, always choose a service that supports E2E encryption.

LOCK.PUB offers free, end-to-end encrypted file sharing without sign-up. Without the password, no one — not even us — can open your files.