Secure Messaging · GrapheneOS

Signal vs Threema on GrapheneOS — which to use, when, and why both.

Honest comparison of the two best secure messaging options on a degoogled Pixel. Written for Australian buyers, with Threema setup notes and the trade-offs we have actually hit in customer migrations.

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Short answer

Use both. Threema as your primary identity, Signal as your fallback for people who already use it. They solve different problems — treating them as redundant is a mistake.

Threema — your private identity. No phone number, no email, no account. Hash-based ID. Pay once with crypto and your entire messaging identity is anonymous from registration.
Signal — your reach layer. Most privacy-curious contacts already have it. Best E2E encryption pedigree. Still requires a phone number to register, even if usernames-only after.

Side-by-side

Property	Signal	Threema
End-to-end encrypted	Yes	Yes
Phone number required to register	Yes	No
Email required	No	No
Open-source client	Yes	Yes (Libre build via F-Droid)
Open-source server	Yes	No
Server jurisdiction	USA	Switzerland
Anonymous payment / signup	Partial (need a number)	Yes (crypto-paid ID)
Disappearing messages	Yes	Yes
Voice / video calls	Yes	Yes
Group chats	Yes	Yes
Desktop client	Yes	Yes (Threema Web)
Runs without Google Play on GrapheneOS	Yes	Yes (native)
Cost	Free	One-off ~$5 AUD

When Threema wins

You do not want a phone number tied to your messaging identity.
You want to pay anonymously with cryptocurrency from day one.
You want the server jurisdiction to be Switzerland, not the United States.
You want messaging in a separate identity envelope to your phone-number identity.

This is why we issue every Privacy Devices customer a paid Threema ID by default. Your Threema ID is yours forever, transferable across devices via export.

When Signal wins

You need to reach people who already use Signal — activist circles, journalists, lawyers, security teams.
You want an open-source server you can audit.
You prefer the most-deployed and most-reviewed E2E protocol available (Signal Protocol).
You need Sealed Sender features that hide message metadata from the relay.

Threema setup on GrapheneOS (Australia)

1. Buy a Threema license

From our shop with crypto, or directly from threema.ch. Either way you receive a Threema ID code.

2. Install Threema Libre on GrapheneOS

Open Apps → Other → F-Droid (we pre-install F-Droid). Add the Threema repository (threema-libre.f-droid.org). Install Threema Libre. This is the Google-Play-free build — no FCM, no Play services dependency.

3. Activate your ID

Enter the activation code. Generate a new Threema ID. Set a strong password. Back up the ID via Threema Safe (encrypted, on Threema servers) or to local file.

4. Verify keys

For sensitive contacts, verify their Threema ID fingerprint in person or over a known-good channel. Verified contacts appear with three green dots.

Signal setup on GrapheneOS

1. Use a number you actually own

Signal still requires a phone number for registration. Use a real number you control. Burner-style numbers may be flagged.

2. Install Signal

Either via Sandboxed Google Play in a secondary profile, or download the APK directly from signal.org. Both work on GrapheneOS.

3. Set a username

Settings → Profile → Username. Once set, contacts can reach you by username and do not see your number.

4. Lock the registration

Enable Registration Lock with a strong PIN. This prevents an attacker who SIM-swaps your number from re-registering Signal as you.

Frequently asked questions

Should I use Signal or Threema on GrapheneOS?

Use both. Threema as your primary identity (no phone number, paid one-off ID), Signal for contacts who already use it. They solve different problems and are not redundant.

Is Threema actually private if I have to pay for it?

Yes — and the payment is the privacy mechanism. There is no phone number, no email, and no account anywhere. Your Threema ID is a hash. Pay with crypto and the entire transaction is anonymous.

Does Signal require a phone number?

Yes. Signal still requires a phone number to register, although you can use a usernames-only profile after registration so contacts can reach you without your number. The registration phone number can be a virtual number or an Australian number you control.

Are both end-to-end encrypted?

Yes. Both use audited end-to-end encryption. Signal Protocol is the more widely deployed and reused (WhatsApp, others use it). Threema uses NaCl-based encryption with separate identity and message keys.

Where is the metadata stored?

Threema stores nothing on its servers after delivery. Servers are in Switzerland. Signal stores minimal metadata (account creation, last connection date) — no message content, no contact graph beyond hashed contact discovery. Servers in the United States.

Do I need Sandboxed Google Play to use them on GrapheneOS?

No. Threema runs natively on GrapheneOS — install via F-Droid (Threema Libre build) or sideload the official APK. Signal also runs without Google Play, though some advanced push features benefit from Sandboxed Google Play in a separate profile.

Do you pre-install both on Privacy Devices phones?

Yes. Every Privacy Devices Pixel ships with Threema activated against your paid ID and Signal installed and ready for first registration. Mullvad VPN is also pre-keyed.

Skip the setup — get it pre-configured.

Every Privacy Devices Pixel ships with Threema activated, Signal ready, and Mullvad VPN keyed. First-week setup guide →

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