{
  "$schema": "../../schema/test-vector.schema.json",
  "name": "Group Data Payload",
  "spec_ref": "src/08-payload-group.md",
  "protocol_version": 0,
  "description": "Tests group datagram payload. Same wire format as GRP_TXT but payload type = 0x06. The encrypted plaintext is timestamp(4, LE) followed by an application-defined binary blob.",
  "vectors": [
    {
      "id": "grp-data-001",
      "description": "Group datagram with known channel secret",
      "type": "encode_decode",
      "structured": {
        "header": {
          "version": 0,
          "payload_type": "grp_data",
          "route_type": "flood"
        },
        "path": {
          "hash_size": 1,
          "hash_count": 0,
          "hashes": []
        },
        "payload": {
          "channel_hash": "72",
          "cipher_mac": "EFFF",
          "ciphertext": "70917BC984A0AD4A409C3906B2266144"
        }
      },
      "binary": "19 00 72 EFFF 70917BC984A0AD4A409C3906B2266144",
      "crypto_context": {
        "shared_secret": "202122232425262728292A2B2C2D2E2F303132333435363738393A3B3C3D3E3F",
        "encryption_key": "202122232425262728292A2B2C2D2E2F",
        "plaintext": "00F15365DEADBEEF0102030405"
      },
      "notes": "Header 0x19 = GRP_DATA(6)+FLOOD(1). Channel hash = SHA256(channel_secret)[0] = 0x72. Inner plaintext is the GRP_DATA format: timestamp 1700000000 (00F15365 LE) + the application-defined blob DEADBEEF0102030405. 13 bytes, AES-128-ECB zero-padded to 16. AES key = first 16 bytes of channel secret; MAC = HMAC-SHA256(channel_secret, ciphertext)[0..1]."
    }
  ]
}