MagTek MagneSafe V5 - Manual (Page 25)

Section 2. Communications
17
MagneSafe Version Number
This eight byte field contains the MagneSafe Version Number with at least one terminating byte
of zero to make string manipulation convenient. See the MagneSafe Version Number Property
for more information.
Hashed Track 2 Data
This twenty (20) byte field contains the hashed track 2 data with SHA1 algorithm.
Clear Text CRC
This 2-byte Binary field contains a clear text version of a Cyclical Redundancy Check (CRC-16
CCITT, polynomial 0x1021) (least significant byte sent first). It provides a CRC of all
characters sent prior to this CRC. The CRC is converted to four characters of ASCII before
being sent. The application may calculate a CRC from the data received prior to this CRC and
compare it to the CRC received. If they are the same, the application can have high confidence
that all the data was received correctly. The CRC Flag property controls whether this field is
sent. If the property is True, the CRC is sent, if it is False, the CRC is not sent. The default state
for this property is True.
Encrypted CRC
This 8-byte Binary field contains an encrypted version of a Cyclical Redundancy Check (CRC).
It provides a CRC of all characters sent prior to this CRC. The CRC is converted to 16
characters of ASCII before being sent. After the receiver decrypts the message, the CRC is
contained in the first 2 bytes of the message, all other bytes are meaningless. The application
may calculate a CRC from the data received prior to this CRC and compare it to the CRC
received. If they are the same, the application can have high confidence that all the data was
received correctly. The CRC Flag property controls whether this field is sent.
CARD DATA (KB AND OTHER MODELS)
The card data is converted to ASCII and transmitted to the host as if it had been typed on a
keyboard. Any data with ASCII values 0 – 31 or 127 will be transmitted as their equivalent
control code combination. For example a carriage return value 13 (0x0D) will be sent as (^M)
where ^ represents the Ctrl key on the keyboard.
Caution
When using a USB Keyboard Emulation reader, if another
keyboard is connected to the same host as this reader and a key is
pressed on the other keyboard while this reader is transmitting,
then the data transmitted by this reader may get corrupted.
The reader’s programmable configuration options affect the format of the card data. During
normal reader operation, the reader acts like a USB HID keyboard so the host operating system
takes care of all low level communications with the reader so that the application developer is
not burdened with these low level details.