Double Ratchet Algorithm: Difference between revisions

Revision as of 00:20, 22 July 2023

Revision as of 09:09, 19 October 2023

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| caption2 = Diagram of the working principle

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A client renewsattempts to renew session key material in interactioninteractively with the remote peer using a Diffie–Hellman (DH) ratchet. wheneverIf possiblethis is impossible, otherwisethe independentlyclients byrenew the session key independently using a hash ratchet. Therefore, withWith every message, a client using the double ratchet advances one of two hash ratchets (oneratchets—one for sending, and one for receiving). whichThese two hash ratchets get seeded with a common secret from a DH ratchet. At the same time it tries to use every opportunity to provide the remote peer with a new public DH value and advance the DH ratchet whenever a new DH value from the remote peer arrives. As soon as a new common secret is established, a new hash ratchet gets initialized.

As cryptographic primitives, the Double Ratchet Algorithm uses