RFID Reader/Writer
The RFID Reader/Writer allows for writing to and reading from RFID Chips.
Data Format
The data format complies to the format of a MIFARE Classic contactless smart card, however, value blocks and their functions (increment, decrement, restore, transfer) are not implemented.
Quick Overview
Data Blocks
Each card has 16 sectors, each with 4 blocks of 16 bytes. The first block is a manufacture block, is read-only (regardless of access permissions), and contains the UUID of the chip in its first 7 bytes. The last block in each sector is named the sector trailer block and contains the two keys for the sector and the bits that determine access permissions.
UUID
Each ID is guaranteed to be unique at the time of crafting. Duplicating the item (e.g. creative mode) can create a situation where the ID is no longer unique to one chip. The range of IDs is 0x00-0xffffffffffffff. IDs will loop back to zero after the max has been reached, causing new chips to no longer be created with unique IDs.
Access Permissions/Keys [Sector Trailer]
The first 6 bytes of a sector trailer block make up key A. The last 6 bytes make up key B. The 3 bytes after key A are used to determine the access bits. One byte after the access bytes can be used as data storage. By default key A has permissions to read and write to all blocks in the sector, but it can never read itself. Key B will not be able to be used for authentication since it can be read by key A.
View the MIFARE Classic documentation section 8.7.1 for detailed information about the access bits.
Note: Care should be taken when writing to a sector trailer as setting incorrect access bits will lock the sector permanently.
Note: Changing a key will take effect immediately.
Functions
| Function | Returns | Description |
|---|---|---|
| search() | table uid | Searches for any RFID chip (or chipped item) within a radius of 3 blocks and returns its ID. First, entities' inventories will be searched. Then, tile entities will be searched. If a valid item is in the reader/writer slot, it will take priority. Returns nil if no item was found. The id will be a table of bytes[1]. |
| select(table uid) | nil | Specifies an RFID chip that will be used by other commands. The uid should be a table of seven bytes[1] |
| auth(number key_type, number block, table key) | nil | Specifies a key to use for authentication. Valid key types are 0 and 1 for keys A or B. The specified block is used to determine which sector this key can be used to authenticate against. The key should be a table of six bytes[1]. |
| deauth() | nil | Clears the stored authentication key |
| read(number block) | table block_data | Attempts to read the specified block. If there is no auth key, no chip has been selected, or the selected chip cannot be found, nil will be returned. Otherwise, a table of 16 bytes[1] will always be returned. The bytes returned can be zeros depending on the access permissions for the block. |
| write(number block, table data) | boolean success | Attempts to write data to a block. If there is no auth key, no chip has been selected, or the chip cannot be found, false will be returned. The write operation will fail silently if authentication fails. Bytes are only written if the access permissions for the block allow it. |
- unsigned integer with the range 0-255
Search Pattern
The RFID reader/writer begins its search at a one block radius and continues to expand until either an RFID item is found or the max search radius has been reached.
The following list shows the order that the RFID reader/writer will take when searching for RFID items per block.
- Entities
- Player Inventories
- Items In-World
- Items Held by Entities
- Embedded Tags. See RFID Chip Prod
- Tile Entity Inventories