ATAES132-TH-EQ Atmel, ATAES132-TH-EQ Datasheet - Page 60

• Manufacturer Part Number: ATAES132-TH-EQ
• Description: EEPROM AES 32Kbit EE SPI
• Manufacturer: Atmel

Specifications of ATAES132-TH-EQ

• Rohs: yes
• Maximum Clock Frequency: 10 MHz
• Operating Supply Voltage: 6 V
• Maximum Operating Temperature: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Package / Case: TSSOP-8
• Interface Type: SPI
• Factory Pack Quantity: 2300

7.21.
7.21.1. Nonce Synchronization
NonceCompute Command
The NonceCompute command generates the nonce in a manner which allows two ATAES132 devices to have identical
random nonces based on random numbers generated by both devices. The identical nonce values and identical MacCount
values are required to encrypt data on one device for decryption by the other device.
The random command must be executed with mode bit 2 = 1b prior to execution of the NonceCompute command. The
random command generates a random number which the NonceCompute command combines with the RandomSeed
provided by the second ATAES132 to generate the random nonce.
The nonce remains valid until one of the following events occurs:
The following procedure synchronizes the nonce and the MacCount on two ATAES132 devices. In this procedure, the device
where the procedure begins is referred to as “A” and the device it is synchronized with is referred to as “B”.
Table 7-63. Input parameters
Opcode
Mode
Param1
Param2
Data
•
•
•
1.
2.
3.
4.
A MAC compare operation fails
The MacCount reaches the maximum count (see Section I.1)
Due to the WakeUp from the sleep power state, the cryptographic state machine is reset due to either (see Section
The random command is executed on Device A with mode bit 2 set to 1b. The first 12 bytes of the random field
The nonce command is executed on Device B with mode bit 1 set to 1b. The 12 byte random number generated in
The NonceCompute command is executed on Device A, using the 12 byte random number generated in step 2 as
Successful execution of this procedure sets the nonce status flags on both devices to NonceValid = YesNonce,
G.2.2):
value in the response are stored for use in step 2.
step 1 is used as the nonce command InSeed field value. The 12 byte random field value in the response is stored
for use in step 3.
the RandomSeed field value.
NonceRandom = Random, and NonceCompute = No. The MacCount is zero on both devices.
•
•
•
Receipt of a reset command
Power cycling (POR), or
Activation of the initialization sequence
This command resets the MacCount to zero only if the operation succeeds (see Section I.1). If an error occurs,
the contents of the nonce register and the MacCount register remained unchanged – the NonceValid flag also
remains unchanged.
Name
NonceCompute
Mode
Zero
Zero
RandomSeed
(Bytes)
Size
12
1
1
2
2
Notes
0x13
The value of this field must match the mode field value used when
executing the nonce command on the origin device
Always 0x0000
Always 0x0000
First 12 bytes output by the Nonce command on the origin device
Atmel ATAES132 Preliminary Datasheet
8760A−CRYPTO−5/11
60