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AT88SC102

1K EEPROM– Security Logic with Two Application Zones

Unspecified 

6. Memory Zones

Table 6-1. Memory Zones

Zone

Definition

Security Code Attempts

Counter SCAC (16 bits)

The protocol for verification of the security code requires that the user write one of the first four bits of

the SCAC to a logic “0”. This allows the SCAC to count the number of consecutive incorrect

presentations of the security code. After four consecutive incorrect security code presentations, the

first four bits of the SCAC will all be written to “0”, and the user is permanently blocked from access to

the application zones, as well as other areas controlled by the security code. After a successful

presentation of the security code, the entire 16-bit SCAC, including the four active bits, should be

erased. This verifies that the correct security code has been presented, since an erase operation in

this area is not allowed without SC verification. It also clears the SCAC bits in preparation for the next

use of the card. This erase operation will also clear the remaining twelve bits of the 16-bit SCAC word.

These twelve bits may be used in an application, although the entire 16-bit word will be erased if any

bit in the SCAC is erased.

Code Protected Zone

CPZ (64 bits)

Read access to this area is always allowed and does not require SC validation. The security code

must be correctly presented to allow write or erase access to the code protected zone.

Application Zones 1 and 2

AZ1 and AZ2

(512 bits each)

The application zones (AZ1 and AZ2) are intended to hold user application data. P1 (address 176)

controls write access, and R1 (address 177) controls read access within AZ1. P2 (address 736)

controls write access and R2 (address 737) controls read access within AZ2. In Security Level 1, an

entire 16-bit word will be erased if an erase is performed on any single bit within that word. In Security

Level 2, erase operations are controlled by both the SV flag and the erase keys (EZ1 and EZ2). See

the Device Operation ERASE definition for specific details. The number of erase operations performed

in AZ2 may be limited by leaving the EC2EN fuse set to “1”. The AT88SC102 allows unlimited erase

operations of AZ1.

Application Zone

Erase Keys

EZ1 (48 bits)

EZ2 (32 bits)

(Enabled in Security Level 2 only) The erase keys are passwords used to control erase operations

within the application zones, after the issuer fuse has been blown (Security Level 2). The erase key

passwords are written by the issuer during personalization (Security Level 1), after verification of the

security code. EZ1 and EZ2 can not be changed after the issuer fuse is blown. In Security Level 2, the

AT88SC102 allows only block erasure of an entire application zone. AZ1 can be erased only after both

the SC and the EZ1 password have been validated. Verification of EZ1 will set the internal flag E1 to

“1”. AZ2 can be erased only after both the SC and the EZ2 password have been validated. Verification

of EZ1 will set the internal flag E1 to “1”. Verification of EZ2 will set the internal flag E2 to “1”.

Application Zone 2

Erase Counter EC2

(128 bits)

(Enabled in Security Level 2 only) The Application Zone 2 Erase Counter (EC2) is enabled only in

Security Mode 2 and only when the EC2EN fuse is set to “1”. If both of these conditions are true, the

user will be limited to 128 erase operations in Application Zone 2. EC2 is used to count these erase

cycles. The erase protocol for the AT88SC102 Application Zone 2 requires one bit in EC2 to be written

to “0”. After 128 erase operations, all 128 bits in EC2 will be “0” and the user will be blocked from

erasing AZ2. The erase counter is only writeable and cannot be erased. When the EC2EN fuse = “0”,

the EC2 operation is disabled. In that case there is no limit to the number of times AZ2 can be erased,

and EC2 has no function.

Memory Test Zone

MTZ (16 bits)

All operations are allowed for this zone (write, erase, read). The purpose of this zone is to provide an

area in the product memory which is not restricted by security logic. It is used for testing purposes

during the manufacturing process, and may also be used in the product application if desired,

although no security protection exists for the MTZ.

Manufacturer’s Zone

MFZ (16 bits)

The MFZ is intended to hold data specific to the smart card manufacturer (like assembly lot codes,

dates, etc.). Read operations within this zone are always allowed. Write or erase operations within this

zone are allowed after the SC has been verified. After the data is entered by the card manufacturer,

the manufacturer’s fuse can be blown and the data within the MFZ will become read-only. Blowing the

issuer fuse will also lock the data in the MFZ.

6 AT88SC102

1419C–SMEM–6/08

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