Protocols

Technical reference for OctoMY™'s wire protocols, packet formats, and communication layers.

Security Note

All established OctoMY sessions use AES-256-GCM encryption with RSA-2048 key exchange. The "multimagic" header (OctoMYM!) allows rapid packet filtering before any crypto operations, providing efficient DoS protection while maintaining full encryption for authenticated traffic.

Protocol stack

Default ports

Packet structure

Basic packet format

Multimagic header

The first 8 bytes identify OctoMY™ packets:

const uint64_t MULTIMAGIC = 0x4F63746F4D594D21;  // "OctoMYM!"

Purpose:

• Identify OctoMY™ packets vs. other UDP traffic
• Protocol version detection
• Early packet rejection for security

Session ID

8-byte unique session identifier:

struct SessionID {
    uint32_t local_id;   // Unique per node
    uint32_t remote_id;  // Assigned by peer
};

Sequence and ack numbers

Packet flags

Common flag combinations

Handshake protocol

Three-way handshake

Handshake packet content

SYN Packet:

SYN|ACK Packet:

Encryption

Key exchange

1. Both nodes generate RSA-2048 key pairs
2. Exchange public keys in SYN/SYN|ACK
3. Derive shared AES-256 session key using:
   • Both nonces
   • ECDH key agreement
   • HKDF key derivation

Encrypted payload

Reliability system

Reliable vs. Unreliable

Reliable delivery

Retransmission

Flow control

Sliding window

Congestion control

Discovery protocol

Multicast discovery

Discovery packet

NAT traversal

Hole punching

Punch protocol

1. Both nodes register with Zoo server
2. Zoo provides peer's external address
3. Both send simultaneous UDP packets
4. NAT creates mapping, allowing responses
5. Direct communication established

Blob transfer protocol

Large data transfer

For data larger than MTU (~1400 bytes):

Blob Header:

Chunk Packet:

Blob reassembly

Courier protocol

Courier ID allocation

Standard courier IDs

Heartbeat and keepalive

Keepalive mechanism

Ping/pong packet

Error handling

Protocol errors

Connection errors

Security considerations

Protections

Best practices

• Regenerate session keys periodically
• Use secure random for nonces
• Validate all packet fields
• Rate limit connection attempts