ST1331

The members of the ST1331/1333/1353 family are principally designed for use in prepaid Phonecard applications. Each is a 272-bit EEPROM device, with associated security logic and special fuses to control memory access.

The memory is arranged as a matrix of 34 x 8 cells, accessed in a serial bitwise fashion for reading and programming, and in a byte-wise fashion for internal erasing. An on-chip address counter provides an internal address space of up to 512 bits. Each member of the ST1331/1333/1353 family has an identification data area, unit-counters (with an anti-tearing mechanism for reliable usage in open readers), a post validation certificate, an issuer area (ST1331) or an authentication secret key area (ST1333/1353), and a user area.

This is summarized in Figure 2. The validation certificate allows the recognition of the ST1331 by the appropriate security module. The anti-tearing mechanism guards against extra, spurious count signals being executed when the card is unexpectedly extracted, while an operation is underway, in an open reader.