P2SN is a Peer to Peer, encrypted Socket Network written in python. P2SN uses asymmetric/public key encription (RSA) for all* communication between the two peers. P2SN uses Base64 (with the '+' and '/' characters) to encode and decode everything**.

*: Everything, except PUBKEY, pubkey, ERRORKEY, and NULL.

**: Everything, except PUBKEY, ERRORKEY, and NULL

You can read the official P2SN standard in the standard.md file.

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sequenceDiagram
    participant SERVER
    participant CLIENT
    CLIENT->>SERVER: What's your public key?
    SERVER->>CLIENT: It's 12642607...
    CLIENT->>SERVER: [KEYCHECK]
    SERVER->>CLIENT: What's your public key?
    CLIENT->>SERVER: It's 12642607...
    SERVER->>CLIENT: [KEYCHECK]

b"..." means a bytes string. \x04 marks the end of the message, ASCII code 4. [KEYCHECK] is simply used for checking if the peer received the right key correctly. The bytes b"P2SN:KEYCHECK" are encrypted. [ERRORKEY] is b"P2SN:ERRORKEY"

The client and the server must have a public, and a private RSA key. Minimum recommended keysize: 1024 bits.

• Client connects to server.
• Client sends b"P2SN:PUBKEY\x04"
• Server sends its public key saved with pkcs1 PEM encoded with Base64 + b"\x04"
• Client sends encrypted [KEYCHECK] encoded with Base64 + b"\x04"
  • If error happens, server replies with [ERRORKEY] + b"\x04"
• Server sends b"P2SN:PUBKEY\x04"
• Client sends its public key saved with pkcs1 PEM encoded with Base64 + b"\x04"
• Server sends encrypted [KEYCHECK]
  • If error happens, client does nothing.

The client must be initialized. The client is initialized if its connected to the server, and the key exchange successfully happened (see above).

• Client sends message encrypted with the server's public key, encoded with Base64 + b"\x04"
• Server replies with message encrypted with the client's public key, encoded with Base64 + b"\x04"