Password Protection & Email Delivery: Sharing Files on Your Terms
SecureEU Team
Privacy & Security
End-to-end encryption is only half the story. Once your file is encrypted and uploaded, you need a safe, convenient way to share the download link. SecureEU now offers two features that give you full control: password protection and built-in email delivery.
Password-Protected Transfers
After your file is uploaded, you can set a password on the transfer. When your recipient opens the download link, they'll see a lock screen and must enter the correct password before they can decrypt and download anything.
🔒 How Password Protection Works
- You choose a password (minimum 4 characters) after upload completes
- The password is hashed with SHA-256 before being sent to the server — we never see the plaintext
- Incorrect attempts are throttled with a 500 ms delay to prevent brute-force attacks
- The password adds a second layer on top of the E2E encryption key already in the URL
This means even if someone intercepts the download link, they still can't access the files without the password. You share the link through one channel (e.g. email) and the password through another (e.g. a text message) for maximum security.
Built-In Email Delivery
Instead of copying the link and pasting it into your own email client, you can send the download link directly from SecureEU to up to 20 recipients at once. We send a clean, branded email with the download link — no ads, no tracking pixels, no third-party scripts.
How Email Delivery Works
- 1. After your file is uploaded and the link is ready, enter one or more email addresses
- 2. SecureEU sends each recipient a professionally designed email with the download link
- 3. Recipients click the link, enter the password (if set), and download instantly
Emails are sent via SendGrid, an industry-standard transactional email service. We send from our own
verified domain, so your recipients see a clean SecureEU Transfers sender —
not a suspicious-looking URL.
Zero-Knowledge Stays Intact
A natural question: if you're emailing the download link, does SecureEU see the encryption key?
No. The encryption key lives in the URL fragment (the part after #).
The email contains the full link including the fragment, but this is assembled in your browser before being sent.
Our email service delivers it as an opaque string — it has no concept of what the fragment means or how to use it.
The zero-knowledge guarantee is fully preserved.
When to Use Each Feature
| Scenario | Recommendation |
|---|---|
| Sending to a colleague over Slack | Link only — low risk |
| Sending legal documents | Link + password (share password by phone) |
| Distributing files to a team | Email delivery to all recipients |
| Maximum security | Email delivery + password via separate channel |
Both Features Are Free
Password protection and email delivery are included with every transfer — free or paid. Whether you're sending a 100 KB contract for free or a 40 GB video archive, you get the same sharing tools.