Cwtch¶

Best suited for: Users on supported platforms who accept Tor and a specialised tool. [1] [2] [3] [4]
Avoid if…: You use iPhone or need calls. [1] [2] [3] [4]
Main strength: Onion architecture without a single central account server. [1] [2]
Main weakness: No iOS; niche ecosystem and more limited assurance. [1] [2]
Account identifier: Local / onion profile; no phone or email required. [1] [2]
iOS: No official client established in the study. [1] [2]
Android: Yes, client listed in the study. [1]
Windows: Yes, client listed in the study. [1] [2]
macOS: Yes, client listed in the study. [1] [2]
Linux: Yes, client listed in the study. [1] [2]
Confidence and scope: More limited current assurance and audits; Tor does not establish global resistance. [1] [2]

What your contact learns¶

What the contact learns: The contact receives messages and the profile you share, and can keep a copy. [1] [2]

What the provider learns: No single central provider; relays and peers have local visibility. [1] [2]

What the network / ISP learns: The network sees destinations, timing and volume; Tor or a relay changes the observer. [1] [2]
Apple / Google exposure: Store, installation and push can create metadata; exact profile linkage depends on the OS and was not tested here. [1] [2]
Public law-enforcement evidence: No individual disclosure case established here; this does not prove an absence of requests or data. [1] [2]

E2EE: E2EE through onion services according to published design. [1] [2]
Forward secrecy: Unknown: not established for the version and configuration in question.
Post-compromise security: Unknown: not established for the version and configuration in question.
Key verification: Unknown: not established for the version and configuration in question.

Metadata exposure: Reduced central concentration; presence and traffic correlation remain possible. [1] [2]
Global user ID: Persistent onion identity; no single central account. [1] [2]
Username / discovery: Unknown: not established for the version and configuration in question.
Push notifications: Unknown: not established for the version and configuration in question.

IP exposure to peer: Messages through onion; no established calls; Tor does not defeat a global observer. [1] [2]
Relay / TURN: Onion / Tor services with distributed visibility. [1] [2]
Calls: No current calls established in the study. [1] [2]
Groups: Unknown: not established for the version and configuration in question.

Multi-device: Unknown: not established for the version and configuration in question.
Backups: Unknown: not established for the version and configuration in question.

Audits: Unknown: not established for the version and configuration in question.
Source code and binaries: Repositories and component-specific scopes recorded in Phase 2; no current binary rebuilt bit-for-bit here. [1] [2]
Main weakness: No iOS; niche ecosystem and more limited assurance. [1] [2]
Public law-enforcement evidence: No individual disclosure case established here; this does not prove an absence of requests or data. [1] [2]

Recommended configuration: Control devices, identities, notifications and files; verify client, version and calling path. [1] [2]
Remaining unknowns: Current network behaviour, distributed binaries and forensic evidence remain incomplete; check version, OS and configuration. [1] [2]

End-to-end encryption — E2EE

Participants’ devices control content keys. The transport server should not read ordinary messages. Learn more

Metadata

Data around the exchange: accounts, IP, timing, volume, devices or groups. Learn more

Pseudonymity

Use an identity different from your civil identity. It can still be linked to you. Learn more

Network anonymity

Reduce the ability to link traffic to your network address or its destination. Learn more

The detailed evidence is maintained in the French Phase 2 register. The translation is a restatement, not new evidence.