Yes, in Routed sessions the media is encrypted between all clients and the media server. In Relayed sessions the media is encrypted between each pair of clients. When a client is connecting to an OpenTok media server or another client, the cipher to use will be negotiated. If the client supports AES-256 then this will be the cipher negotiated for the media traffic. If the client does not support it, then AES-128 will be used. In the case of Relayed sessions, both clients must support AES-256, otherwise they will fall back to AES-128.
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