Security and Privacy, Without the Jargon

A Sealed Envelope Only Your Contact Can Open

When you send something, your phone puts it in a sealed envelope before it leaves. Only your contact’s phone has the key to open it. On the way it goes through our server, which holds it until it’s delivered but can’t open it. This is called end-to-end encryption, and in TruchiChat it’s always on: for messages, photos, videos, voice notes, files, contacts, places on the map and calls.

Each message is sealed with a new key. The keys that open your messages are created on your phone and never leave it: on iPhone they live in that iPhone’s Keychain, without iCloud; on Android, encrypted with a key from the phone’s secure storage.

What Our Server Sees

No messaging service is invisible: to deliver an envelope, you need to know who it’s for. This is what ours needs, and nothing more:

• Your account: an identifier, the name you choose, your public keys (the ones used to seal envelopes, not to open them) and your session.
• Which account writes to which and when, in which chat, and the approximate size of what’s sent.
• The app version, the system version and the phone model, for support.
• Whether you’ve muted a chat, so it doesn’t send you the notification.
• Your IP address while you’re connected, like any server you connect to.

And it never sees: the text, photos, videos, voice notes, files, calls or places you send. Not your phone number or email either, because we don’t ask for them.

Anything not yet delivered is deleted after 24 hours at most. If you delete your account, everything of yours is deleted. More detail in the guide and in the privacy policy.

Notifications Give Nothing Away

The lock screen notification says who’s writing and “New message.” Never the text. On iPhone, that name is sealed inside the notification and Apple doesn’t see it. On Android with Google Play, Google’s notification only wakes the app: it carries neither the text nor the sender. The Android without Google version goes through neither Apple nor Google: it has its own connection.

Check You’re Talking to the Right Person

When you accept an invitation, the app saves your contact’s key. If it ever changes, the app warns you and the chat waits until you accept it. To be completely sure, compare the safety number, 60 digits that both phones see the same, by scanning each other’s QR code in person. Step by step.

Your IP in Calls

In a call, the two phones usually talk directly, so each one sees the other’s IP address. With “Hide My IP in Calls,” in Settings, the call goes through our relay server and your contact doesn’t see yours. The call is still encrypted from one phone to the other: the server passes it along, it doesn’t hear it.

On Your Phone

• Your history is stored encrypted and isn’t copied to the cloud or to another phone.
• You can lock the app with Face ID, Touch ID or your passcode on iPhone, and with your fingerprint or face on Android.
• The connection to our server is encrypted, and the app only trusts our certificates.

What You Delete

On a phone, deleting doesn’t mean writing zeros over the data: its storage can’t guarantee that. What protects deleted data is that chats are stored encrypted, and anything that might remain on the disk can’t be opened without the history key, which never leaves that phone. Each chat has its own key: it changes when you clear the chat and is deleted when you delete the chat or your account. On the server, clearing a chat for both of you immediately deletes anything still waiting to be delivered.

TruchiChat’s Code Is Private

TruchiChat’s code is private. Your security doesn’t depend on that: your messages are encrypted on your phone with public, well-studied algorithms, the key never leaves it and the server only sees sealed envelopes. And you can check your contact with their safety number.

The algorithms are X25519 to agree on keys, ChaCha20-Poly1305 to seal the envelopes and Ed25519 to sign; on iPhone, Apple’s CryptoKit implementations, and on Android, Bouncy Castle’s. Calls use WebRTC, encrypted from one phone to the other. No outside party has audited TruchiChat, and we won’t say otherwise until it’s true.

What It Doesn’t Do

• There are no groups, no cloud backup, no computer version and no using the same account on several phones. Each of those would be another copy of your data.
• The server knows which account writes to which. There’s no way to deliver a message without knowing that.
• If someone ever managed to steal the keys from your phone, the conversation doesn’t “heal” on its own. The safe thing to do then is delete your account and create a new one.
• Saving a photo or video to your photo library takes it out of TruchiChat: there it’s no longer encrypted.