$$ \newcommand \WS {\mathrm{WS}} \newcommand \PtoP {\mathrm{P2P}} \newcommand \Peer {\mathrm{Peer}} $$

Addressing

The following section presents how the two Algorand network layers (\( \WS \) and \( \PtoP \)) resolve peer addressing, to univocally identify themselves amongst \( \Peer \)s, establish two-way connections, and effectively route messages regardless of the underlying architecture.

Websocket Addressing Scheme

The Relay Network \( \WS \) relies on an ip:port scheme to let a \( \Peer \) present itself to and address other peers.

This schema is defined in the NetAddress parameter of the node configuration.

See details in the node configuration non-normative section.

The PublicAddress also can be set in the node configuration to let a \( \Peer \) differentiate itself from other peers, and to be used in the identity challenges.

⚙️ IMPLEMENTATION

The reference implementation checks the scheme of network addresses against this regex:

^[-a-zA-Z0-9.]+:\\d+$

⚙️ IMPLEMENTATION

Websocket network address reference implementation.

P2P Addressing Scheme

The Peer-to-Peer Network \( \PtoP \) makes use of the underlying libp2p library primitives for \( \Peer \) addressing, identification and connection.

This section relies on the libp2p specifications and developer documentation.

In this addressing scheme, each node participating in the \( \PtoP \) network holds a public and private Ed25519 key pair. The private key is kept secret, and the public key is shared to all participants.

The peer identity (PeerID) is a unique reference to a specific \( \Peer \) within the \( \PtoP \) network, serving as a unique identifier for each \( \Peer \). It is linked to the public key of the participant, as it is derived as hash of said key, encoded in base58.

See libp2p PeerID specification for details on how these are constructed and encoded.

The PeerID are visible and may be incorporated into multiaddresses to route messages.

\( \Peer \) private keys are used to sign all messages and are kept as secrets by the node.

⚙️ IMPLEMENTATION

PeerID are cast-able to str type and are used as plain strings in packages where importing libp2p packages may not be needed.

⚙️ IMPLEMENTATION

A GetPrivKey function manages loading and creation of private keys in the \( \PtoP \) network. It prioritizes, in this order:

1. User supplied path to privKey,
2. The default path to privKey,
3. Generating a new privKey.

⚙️ IMPLEMENTATION

If a new private key is generated, and should be persisted, its default path is "peerIDPrivKey.key" (inside the root directory). The behavior of this lookup is governed by node configuration values P2PPersistPeerID and P2PPrivateKeyLocation (see the Algorand Infrastructure non-normative section).

Multiaddress

A multiaddress is a convention for encoding multiple layers of addressing information into a single “future-proof” path structure. It allows overlay of protocols and interoperation of many peer addressing layers.

When exchanging addresses, peers send a multiaddress containing both their network address and PeerID.

Regular NetAddress (as the scheme presented in the previous section) may be easily converted into a libp2p formatted listen multiaddress.

Given a network address [a]:[b] (where [a] is the IP address and [b] is the open port), the conversion scheme is /ip4/[a]/tcp/[b].

Refer to the libp2p specifications for further detail on this structure.

📎 EXAMPLE

Here are some examples of syntactically valid multiaddresses:

• /ip4/127.0.0.1/tcp/8080, for a multiaddress composed only of a network address listening to localhost on the port 8080.

• /ip4/192.168.1.1/tcp/8180/p2p/Qmewz5ZHN1AAGTarRbMupNPbZRfg3p5jUGoJ3JYEatJVVk, for a multiaddress composed of a network address 192.168.1.1:8180, joined together with the PeerID equal to Qmewz5ZHN1AAGTarRbMupNPbZRfg3p5jUGoJ3JYEatJVVk.

• /ip4/192.255.2.8/tcp/8180/ws, for a multiaddress composed only of a network address 192.255.2.8:8180 indicating that the connection is through websockets ws.

Hybrid Network Addressing Scheme

The hybrid network maintains a single IdentityTracker entity, shared between both network definitions (\( \WS \) and \( \PtoP \)).

Note that a PublicAddress must be set for hybrid nodes to operate properly.

For peer identity deduplication, a signing schema involving both the \( \PtoP \) private key and the \( \WS \) identity challenge is put in place. This is to correlate both \( \Peer \) definitions and prevent it from existing in both \( \Peer \) lists.

See the hybrid network identity challenge for further details on this process.