BOTD #2: Transport Protocol

Overview

All communications between two peers SHOULD be encrypted in order to provide confidentiality for all transcripts and is authenticated in order to avoid malicious interference.

Transport announcement

Each peer MUST decide and MUST announce which transport protocol wants to use for the connection, one or more combined between:

• Clear text insecure
• Onion service onion
• Server-side TLS TLS
• Mutual TLS mTLS
• Noise_XK_secp256k1_ChaChaPoly_SHA256 noise

Each peer SHOULD be reachable on the default TCP port 9945 and, if so, MUST expose then a plaintext HTTP/2 endpoint that announces the chosen transports responding with an AvailableTransport protobuf message, setting the response ContentType as application/protobuf

Data Structures

syntax = "proto3";

enum TransportType {
    INSECURE = 0;
    ONION = 1;
    TLS = 2;
    MTLS = 3;
    NOISE = 4;
}

message Transport {
    TransportType type = 1;
    string name = 2;
    bytes data = 3;
}

message AvailableTransport {
    repeated TransportType transport = 1;
}

Each Transport has an optional data field that can be used to return additional metadata. Eg. A static public key in case of noise or a self-signed TLS certificate in case of mTLS