ATSGA204A View Datasheet(PDF) - Microchip Technology
Part Name
Description
MFG CO.
'ATSGA204A' PDF : 93 Pages View PDF
Figure 8-2. Data Flow for DeriveKey Command
ATSHA204A
Security Commands
Input MAC
Parent
Key
SHA
(AUTH)
Mode
Source Nonce
Key
SHA
(Device)
Match
Target
Key
8.5.7
DevRev Command
DevRev command returns a single four-byte word representing the revision number of the device.
Software should not depend upon this value because it may change from time to time.
Table 8-13. Input Parameters
Name
Size
Notes
Opcode
DevRev
1
0x30.
Param1
Param2
Mode
—
1
Must be zero.
2
Must be zero.
Data
—
0
—
Table 8-14. Output Parameters
Name
Size Notes
Success
4
The current device revision number.
8.5.8
GenDig Command
The GenDig command uses SHA-256 to combine a stored value with the contents of TempKey, which
must have been valid prior to the execution of this command. The stored value can come from one of the
data slots, either of the OTP pages, either of the first two pages of the Configuration zone, or retrieved
from the hardware transport key array. The resulting digest is retained in TempKey and can be used in
one of three ways as follows:
1. It can be included as part of the message used by the MAC, CheckMac, or HMAC commands.
Because the MAC response output incorporates both the data used in the GenDig calculation and
the secret key from the MAC command, it serves to authenticate the data stored in the Data and/or
OTP zones.
© 2018 Microchip Technology Inc.
DS40002025A-page 51
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