Letter Sealing is a feature that provides end-to-end encryption (E2EE) for chat messages. E2EE is a communication system designed so that messages saved on our servers are encrypted and cannot be read by anyone except the sender and receiver of the message.
Once the sender and receiver have both turned on Letter Sealing, they will be able to start sending messages with added security.
The following information will be encrypted:
• Text messages (not including messages sent through other services like YouTube)
• Location information
• 1-on-1 voice/video calls
Note: We plan to expand Letter Sealing’s functionality in the future.
If you use LINE for PC with Letter Sealing enabled on the smartphone version of LINE, you will be required to verify your identity the first time you send a message.
For information about verifying your identity to use Letter Sealing on LINE for PC, see this Help article.
Letter Sealing is now turned on by default when you download LINE. As part of our efforts to strengthen the app's security, we've made it so this setting can no longer be turned off.
If you've been using LINE since before these specification changes were made and have Letter Sealing turned off, you can protect your messages by turning Letter Sealing on manually from the smartphone version of LINE.
To turn Letter Sealing on:
1. Tap the Home tab > Settings > Privacy.
2. Turn ON Letter Sealing.
Tap here to go to the Settings menu from your smartphone.
If you're trying to verify your identity so you can use Letter Sealing on LINE for PC, but the verification code entry screen isn't appearing in LINE on your smartphone, restart the smartphone app and try verifying your identity again by referring to this Help article.
Key fingerprints are unique encryption keys that Letter Sealing gives to each user so they can send messages to one another safely and securely.
Note: The actual keys are kept secret and will not appear in LINE chats.
If your key fingerprint matches your friend's, it means your chat is securely encrypted. To check whether your key fingerprints match, follow the steps below.
Note: Key fingerprint confirmation is optional.
1. Tap the menu icon at the top of a chat screen.
2. Tap This chat is protected with Letter Sealing at the bottom of the screen.
3. Compare the key fingerprints on your device and your friend's device.
Note: To compare key fingerprints with your friend, we recommend meeting face-to-face or using a form of communication you trust.
If "This chat is protected with Letter Sealing" doesn't appear, it means Letter Sealing is turned OFF. To turn Letter Sealing ON, follow the steps in this Help article.
To check whether a chat is protected with Letter Sealing, tap the menu icon at the top of the chat screen. If Letter Sealing is turned ON, you'll see "This chat is protected with Letter Sealing."
Note: You'll also see a lock icon at the beginning of the sentence.
If "This chat is protected with Letter Sealing" doesn't appear, see this Help article.