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Wire Packet Formats
Headers as typical.
Data:
| Field | Size | Content |
|---|---|---|
| Public Key | 32 | Identity's public encryption key |
| Signing Key | 32 | Identity's public signing key |
| Name Hash | 10 | Full hash of expanded name |
| Random Hash | 10 | Random Hash [5 bytes] + time[5 bytes] |
| Ratchet | 32 | Ed25519 Ratchet Hash |
| Signature | 64 | Ed25519 signature of signed data |
| Application Data | Varies: 0 - 285 | String or msgpack data |
x25519 public key for encryption/decryption and creation of shared secrets.
Ed25519 public key used for signing, including the Announce
SHA 256 hash of full name, truncated to 10 bytes. Full name consists of the app_name and aspect(s), separated by a period. Example: lxmf.delivery . This is the raw bytes without any string terminator or similar additional bytes.
5 bytes random, 5 time. Further clarification required.
Section incomplete.
Signed data consists of the destination hash, public keys, name hash, random hash, and (if applicable) app_data. Signed using Ed25519 signing key.
Legacy Application Data for Peers and Nodes is a string with the friendly name. Modern Announces use a msgpacked array that contains the name as an array of bytes and the ticket cost, if any.
| Field | Type | Use |
|---|---|---|
| 0 | Array | Friendly name |
| 1 | Byte | Ticket value |
Application Data for Propagation Nodes is a msgpacked list.
| Field | Type | Use |
|---|---|---|
| 0 | Bool | Enable/disable peer (?) |
| 1 | Int32 | Timestamp |
| 2 | Int16 | Max transfer size, kB |
Maximum specified Application Data length on wire is 465 bytes. With a type 1 header, absolute maximum is 481 bytes before violating MDU. An announce, using a type 2 header and with 148 bytes of fixed data, limits the Application Data in an announce to 317 bytes; it is good practice to keep this data as small as possible due to transmission to all stations, including LoRa and RF equipped nodes. Given the limited memory on MCUs, this may be application limited.
The destination hash can be determined by concatenating the Name Hash and Identity Hash (which, in turn, is the SHA hash of the x25519 + Ed25519 public keys, truncated to 16 bits). This allows for full verification of the Name and Destination hashes.