6.9 SHA Command

The SHA command computes a SHA-256 digest for general purpose use by the host system. The SHA command must be executed repetitively to calculate the digest over the entire message. Data can be sent to the command in 1-64-byte blocks. The maximum message length over which a digest can be calculated is limited to 2²⁸ bytes.

Upon successful completion of the command, a 32-byte value is output on the bus. If this value is required for use in a SHA104-TFLXAUTH command, the value must first be stored in the system, then resubmitted as an input parameter to the command. There is no ability to store the value directly in the device.