Construction of the Unique Transaction Reference Number (UTRN)
The Unique Transaction Reference Number (UTRN) shall be a 20 decimal digit which shall be the 19 decimal digits of the PPTD with a 20th decimal digit which shall be appended after the least significant digit of the 19 decimal digit representation of PPTD. This 20th decimal digit shall be the UTRN Check Digit. The UTRN Check Digit shall be calculated according to the requirements of Section 14.8.
The PTUT Supplier MAC shall only be calculated once the 32 most significant bits of PTUT (bits 63-32 of the PTUT) have been populated as per the requirements of Section 14.3.2.
The Remote Party, whose Security Credentials are stored against the Supplier role of the target Device, shall calculate a MAC using the parameters in Table 14.3.4 then setting the PTUT Supplier MAC to be the 32 least significant bits of the 128 bit MAC produced by the MAC calculation.