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| -rw-r--r-- | doc/proto-doc.txt | 37 |
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diff --git a/doc/proto-doc.txt b/doc/proto-doc.txt new file mode 100644 index 0000000..7955847 --- /dev/null +++ b/doc/proto-doc.txt @@ -0,0 +1,37 @@ +Protocol Specification. + +Terminology. + +Client - software instance that interacts with human users and lets them send and +receive encrypted messages over Pica Pica. + +Node - software instance that coordinates Pica Pica network, maintains list of +all active nodes and provides connectivity to clients. + +Connections. +There are 4 types of connections between Pica Pica nodes and clients. + +-client to node (c2n) - control connection from client to node + +-client to client (c2c) - data connection between clients through node acting +as a proxy + +-node to node (n2n) - control & data connection between nodes + +-direct client to client (directc2c) - direct connection between clients, +using IPv4/IPv6/DNS +address of accepting client previously communicated through c2c connection. + +These connections use TCP transport. First 3 connection types start +with TLS 1.2 handshake using anonymous Diffie-Hellman ciphersuite, +connecting host acts as a TLS client, accepting host is TLS server. +After connection type is identified by accepting node, anonymous TLS +session is gracefully closed in case of c2n and c2c connections. Node starts +new TLS session with client in case of c2n, where node acts as a TLS client and +client acts as a TLS server, using client's RSA certificate. In case of +c2c connection node acts as a transparent proxy, sending chunks of data +received from the first client to the second one and vise versa. Clients +establish mutually authenticated TLS session over proxied connection, +initiator client is a TLS client, accepting client has TLS server role. +n2n connection continues to operate in ADH TLS session, as by design nodes +do not store state that identifies them except network address. |