AT88SA10HS(2009) 查看數據表（PDF） - Atmel Corporation

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AT88SA10HS
(Rev.:2009)

CryptoAuthentication Host Security Chip

Atmel Corporation 

AT88SA10HS Host Authentication Chip [Preliminary]

4.6.

BurnSecure

Burns any combination of the first 88 fuse bits. Verification that the proper secret fuse bits have been burned must

occur using the MAC command – there is no way to read the values in the first 64 fuses to verify their state. The 24

status fuses can be verified with the Read command.

The fuses to be burned are specified by the 88 bit input map parameter. If a bit in the map is set to a ‘1’, then the

corresponding fuse is burned. If a bit in the map parameter is 0, then the corresponding fuse is left in its current state.

The first bit sent to the AT88SA102S corresponds to Fuse[0] and so on up to Fuse[87]. Note that since a ‘1’ bit in the

Map parameter results in a ‘0’ data value in the actual fuse array, the value in the Map parameter should be the inverse

of the desired secret or status value. See Section 1.2 for more details.

To facilitate secure personalization of the AT88SA102S, this map may be encrypted before being sent to the chip. If

this mode is desired, then the Decrypt parameter should be set to 1 in the input parameter list. The decryption

(transport) key is computed by the GenPersonalizationKey command, which must have been run immediately prior to

the execution of BurnSecure. In this case, prior to burning any fuses, the input Map parameter is XOR’d with the first 88

bits of that digest from the GenPersonalizationKey command. The GenPersonalizationKey and BurnSecure commands

must be run within a single wake cycle prior to the expiration of the watchdog timer.

The power supply pin must meet the VBURN specification during the entire BurnSecure command in order to burn fuses

reliably. If Vcc is greater than 4.5V, then the BurnTime parameter should be set to 0x00 and the internal burn time will

be 250μs. If Vcc is less than 4.5V but greater than VBURN then the BurnTime parameter should be set to 0x8000 and

the internal burn time will be 190ms per fuse bit burned. The chip does NOT internally check the supply voltage level.

The total BurnSecure execution delay is directly proportional to the total number of fuses being burned. If Vcc is less

than 4.5V, then the total BurnSecure execution time may exceed the interval remaining before the expiration of the

watchdog timer. In this case, the BurnSecure command should be run repeatedly, with each repetition burning only as

many fuses as there is time available. The system software is responsible for counting the number of ‘1’ bits in the

clear-text version of the map parameter sent to the chip – no error is returned if the fuse burn count is too high. Other

than Fuse[87] (see below), the fuses may be burned in any order.

Prior to execution of BurnSecure, the AT88SA102S verifies that Fuse[87] is un-burned. If it has been burned, then the

BurnSecure command will return an error. Fuse[87] must be burned during the last repetition of BurnSecure, optionally

in combination with other fuses.

There are a series of very small intervals during tEXEC_SECURE when the fuse element is actually being burned. The

power supply must not be removed during this interval and the watchdog timer must not be allowed to expire during

this interval, or the fuse may end up in a state where it reads as un-burned but cannot be burned.

Table 19.

Opcode

Param1

Param2

Data

Input Parameters

Name

BURNSECURE

Decrypt

BurnTime

Map

Size

Notes

1 0x10

1 If 1, decrypt Map data before usage. If 0, the map is transmitted in plain text.

2 Must be 0x00 00 if Vcc > 4.5V, must be 0x80 00 otherwise.

11 Which fuses to burn, may be encrypted.

Table 20.

Name

Success

Output Parameters

Size

Notes

1

Upon successful execution, a value of 0 will be returned by the AT88SA10HS.

This command takes a constant time to execute regardless of the number of fuses being burned.

19

8595B–SMEM–09/09

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