Locked on your device. Unlockable only by you.
Here is every layer of encryption in Indo Mail, who holds the keys for each one, and — just as important — the few things that cannot be encrypted and why.
Every layer, and who holds the key.
End to end means only the people in the conversation have the key. In transit and in storage mean our systems hold the key, so they can show, search and check your data.
| What | How it is locked | Who can unlock it |
|---|---|---|
| Every connection to Indo Mail | HTTPS with TLS 1.2 or 1.3; TLS for IMAP and SMTP | You and Indo Mail servers |
| Files, photos and backups in storage | AES-256 in cloud storage in Mumbai | Indo Mail systems |
| Mail between Indo Mail accounts | End to end, on by default: AES-256-GCM per message; the message key is wrapped with an elliptic-curve (P-256) and a quantum-safe (ML-KEM-768) secret | Only the devices of the sender and recipients |
| Subject lines of that mail | Locked with the same message key (can be turned off in Settings) | Only the devices of the sender and recipients |
| Mail to any other email service | Optional: lock it with a password you choose; PBKDF2-SHA256 (310,000 rounds) and AES-256-GCM in your browser | Only people who know the password |
| Replies to a password-protected message | Locked in the recipient’s browser with the same password | Only people who know the password |
| Indo Chat messages | End to end by default, per device keys | Only the devices in the conversation |
| Indo Passwords entries | Locked with your master password (PBKDF2-SHA256, 600,000 rounds, AES-256-GCM) | Only you |
| Private contact and event details | Locked with your Indo Passwords master password | Only you |
| Indo Meet audio and video | Encrypted in transit (DTLS-SRTP); never recorded | The people in the meeting |
The honest limits.
Email is a shared, open system. These parts have to stay readable so mail can be delivered and so we can keep spam and abuse out.
| What stays readable | Why |
|---|---|
| Email addresses of the sender and recipients | Mail servers need them to deliver the message |
| Date, time and size of each message | Needed for delivery, storage limits and sorting your inbox |
| Attachments of end-to-end encrypted mail | Not yet end-to-end encrypted; they are encrypted in transit and in storage and checked for risky files |
| Mail you receive from other email services | It arrives readable unless the sender locked it; we encrypt it in transit and in storage |
| The time of a private event | Needed to send you a reminder; the title, place and notes are locked |
| Name and email of a private contact | Needed so you can write to the person; the other details are locked |
Simple for you, strong underneath.
1. Each device makes its own keys
The first time you use Indo Mail on a phone or computer, it creates an elliptic-curve key pair and a quantum-safe ML-KEM-768 key pair. The private halves stay on that device and are never sent to us.
2. Every message gets a fresh key
A new AES-256-GCM key locks the message and its subject. Nothing is reused between messages.
3. The message key is wrapped for each device
For every device of every person in the conversation — including your own, for your Sent copy — the message key is wrapped with a key made from both an elliptic-curve secret and a quantum-safe secret. Breaking one method is not enough.
4. Only the locked copy reaches our servers
We store the locked message, the wrapped keys and the public keys. We never have a private key or a message key.
Safe from tomorrow’s computers too.
Someone could record encrypted traffic today and try to unlock it years from now with a powerful quantum computer. To protect against this, Indo Mail combines today’s elliptic-curve encryption with ML-KEM-768, a post-quantum method standardised as FIPS 203. Both secrets are needed to unwrap a message key, so your mail stays protected as long as either method holds. Apps that do not yet have a quantum-safe key still receive mail protected by the elliptic-curve key, and get the second key automatically on their next update.
Encryption FAQ
Can Indo Mail read my end-to-end encrypted mail?
No. We never have the keys. We can see who sent it to whom and when, because mail cannot be delivered otherwise.
What happens if I forget the password of a locked message?
Nobody — including Indo Mail — can unlock it. Send a new message with a new password.
Can Lily read encrypted mail, subjects or private details?
No. Lily only ever sees what you choose to give it, and locked content cannot be sent to Lily.
Can I still search?
Search on our servers finds encrypted messages by sender, recipient and date. Words inside locked messages and locked subjects are not searchable on the server.
See the full picture.
How we protect accounts, devices and your data — and what we have not done yet.