Calculate PIN Block for payments ISO8583 standard

How PIN block calculation works

In order to calculate the PIN block , you need the data on the left as input.

Then, we need to consider the standard to use. We will limit to ISO-0 in this case.

Most important thing to start with, is the 4 digit PIN number. Lets's say 1111.

PIN block part one is built from character "0", followed by the length of the PIN, then the PIN number, and then fill the value up to 16 characters with "F".

In our example, 0+4+1111+FFFFFFFFFF=041111FFFFFFFFFF

PIN block part two is built from four zeroes, followed by the card number, without the first 3 digits, and without the last digit. So 12 digits.

In our example, for PAN 5516422217375116, the block will be 0000+642221737511=0000642221737511

Next step is to do a HEX XOR on the two blocks

XOR(block1, block2)

And then, finally, apply a 3DES encryption of the above block with the PIN Encryption key.