The Signal protocol, primarily known for its double ratchet algorithm, is used for end-to-end encryption of messages by the following chat applications and protocols. Many users are unaware that they are already benefiting from the security offered by the Signal protocol.
Chat Applications:
Signal app
Skype: only available in the "Private Conversation"
Facebook Messenger: only available in the "Secret Conversations”
Simplex chat
Keychat
Chat Protocols:
XMPP
OMEMO is an XMPP Extension Protocol (XEP) for secure multi-client end-to-end encryption. It is an open standard based on a Double Ratchet and PEP, which can be freely used and implemented by anyone.
https://conversations.im/omemo/
Matrix
Olm (libolm) is an independent Apache-licensed implementation of the Double Ratchet cryptographic ratchet in C & C++, which also includes the new Megolm group ratchet as used in Matrix.
https://github.com/matrix-org/olm nostr:note1ffgsgvkltl96wzwe6lakv2ntjfkq2u48msx57mrvnnhtyde5s2js8antlr
