CryptoCompanion Chip

21

5277C–CryptoCompanion–9/09

Table 31.

Inputs

Table 32.

Outputs

3.10.

GetRandom

The AT88SC018 generates a 20 byte random number using its internal high quality random number generator and

outputs this value. There is no restriction on the system as to where these random numbers may be used – their

cryptographic quality makes them suitable for any operation on the system in addition to the CRF operations.

When the AT88SC018 is unlocked, the random numbers generated will follow a predictable pattern based on the state

of the RNGSeed EEPROM value and the number of power cycles since this seed has been written. This mechanism

facilitates testing.

Table 33.

Inputs

Table 34.

Outputs

3.11.

IncrementCounter

Increment the value of the specified counter by 1.

Table 35.

Inputs

Table 36.

Outputs

Name

Size

Description

Size

1

One less than the number of bytes to be sent through crypto engine. If this byte is 0 grind

1 byte, if 0x13 grind 20 bytes. If

≥ 0x14, return BadCmd.

Data

⎯

Crypto engine input bytes, maximum 20.

Name

Size

Description

Data

⎯

Crypto engine output bytes, maximum 20.

Name

Size

Description

Name

Size

Description

Data

20

Random bytes from the RNG

Name

Size

Description

Counter

1

Counter index to be incremented, must be from 0-3. The upper 4 bits of this parameter are

ignored.

Name

Size

Description