An implementation of the double ratchet in Javascript:

https://github.com/rongarret/ratchet-js

based on an earlier implementation I did in Common Lisp:

https://github.com/rongarret/tweetnacl/blob/master/ratchet.l...

For anyone sensitive to metadata collection (phone numbers), there's SimpleX.chat which is private and secure by default. If you want more complete metadata protection you will also want Orbot (in Power User Mode) and make the following config changes in SimpleX:

Network & servers > Use SOCKS proxy - ON

Network & servers > SOCKS proxy settings > Proxy - 127.0.0.1:9050

Network & servers > SOCKS proxy settings > Use .onion hosts - Required

Network & servers > SOCKS proxy settings > Use random credentials - ON

Network & servers > Advanced network settings > Private routing - Always

Network & servers > Advanced network settings > Allow Downgrade - No

Network & servers > Advanced network settings > Show message status - ON

Network & servers > Advanced network settings > Transport isolation - Chat profile

Audio & video calls > Always use relay - ON [NOTE: get a good VPN to protect call metadata]

Privacy & security > Send link previews - OFF

Privacy & security > Show last messages - OFF

Privacy & security > Auto-accept images - OFF

Privacy & security > Blur media - [As desired]

The above configuration beats the pants off Session (Signal alternative typically recommended) and actually works decently (unlike Session)!

IMO the above really needs to come set by default and I might fork the client to do it (calling it SimplerX).

This article sort of addresses a question that I have had for a long time. I always wondered why it was called a "double" ratchet. There is only one hash ratchet. The triple Diffie-Hellman isn't anything like a ratchet. From the article it seems that the 3DH is called a ratchet anyway. Show 1 reply

The new “gold standard” here for anyone who’s interested is now an IETF standard.

https://datatracker.ietf.org/doc/rfc9420/