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4.2.9 Decrypt Data (0x09)
Table 4.9
The Decrypt Data command takes as arguments the Decryption Key Number (0x00 or 0x01), the Initialization Vector
Number (0x00 or 0x01), the Data Buffer Offset (16-bytes) and the Data Length (16-bytes). This command decrypts
the ‘Data Length’ number of 16-bytes blocks using the AES128 CBC decryption methodology. It operates only within
the Data Buffer. This decryption method is shown in Figure 4.2.
Figure 4.2
Command Number
Command Name
Valid Tag Types
Argument Offset [bytes]
0x00 0x01 0x02 0x03
Argument Name
Decryption Key
Number
Initialization Vector
Number
Data Buffer Offset Data Length
Argument Size [bytes] 0x01 0x01 0x01 0x01
Argument Description
The number of the AES
Key to be used for
decryption. Valid
numbers are 0x00 and
0x01.
Number of the
initialization Vector to
be used for decryption.
Valid numbers are
0x00 and 0x01.
Buffer offset in 16-byte
blocks from where the
decryption is to start.
Total data size and the
offset cannot exceed
the data buffer length.
The number of 16-byte
blocks to be decrypted.
This value has to be
between 1 and 8.
0x09
Decrypt Data
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