ATAES132-SH-ER Atmel, ATAES132-SH-ER Datasheet - Page 114

• Manufacturer Part Number: ATAES132-SH-ER
• Description: EEPROM AES 32Kbit EE I2C
• Manufacturer: Atmel

Specifications of ATAES132-SH-ER

• Rohs: yes
• Maximum Clock Frequency: 1 MHz
• Operating Supply Voltage: 6 V
• Maximum Operating Temperature: - 40 C to + 85 C
• Mounting Style: SMD/SMT
• Package / Case: SOIC-8
• Interface Type: I2C
• Factory Pack Quantity: 2300

I.17.
EncRead Command Configuration Memory Signature MAC
The following example shows how the integrity MAC is calculated for a 512 byte (32 block) certification of the data from the
configuration memory. This operation involves multiple passes through the AES crypto engine, all using the same key, KeyID
00. If the mode parameter indicates that there is an additional block of authenticate-only data, then another pass through the
AES crypto engine is required.
There are 35 passes through the AES crypto engine in CBC mode to create the clear text MAC. The inputs to the crypto
engine for those blocks are labeled B0, B1 and B2 …, and the outputs are B’0, B’1 and B’2 … respectively.
There is one pass through the AES crypto engine in CTR mode to encrypt the MAC.
B0 is composed of the following 128 bits:
B1 is the XOR of B’0 with the following 128 bits:
B2 is the XOR of B’1 with the following 128 bits:
B3 is the XOR of B’2 with the following 128 bits:
B4 is the XOR of B’3 with the following 128 bits:
B’34 is the clear text MAC, which must be encrypted before being sent to the system
A0 is composed of the following 128 bits:
A’0 is XOR’d with the clear text MAC and sent to the system
1 byte flag, fixed value of b0111 1001
12 byte nonce, as generated by the nonce command
1 byte MacCount, 1 for first MAC generation
2 byte length field – always 0x00 00
2 byte length field, value of 528 or 544
14 byte ManufacturingID, Opcode, etc.
16 bytes counter+serial+small, if mode indicates, otherwise this block does not exist
First 16 bytes of config – in the clear
Second 16 bytes of config – in the clear
… and so on …
1 byte flag, fixed value of b0000 0001
12 byte nonce, as generated by the nonce command
1 byte MacCount, 1 for first MAC generation
2 byte counter field – always 0x00 00
Atmel ATAES132 Preliminary Datasheet
8760A−CRYPTO−5/11
114