PinBlock in C#

Implementation of PinBlock Format 0 based on ISO-9564 standard. The PIN block is constructed by XOR-ing two 64-bit fields: the plain text PIN field and the account number field, both of which comprise 16 four-bit nibbles.

The plain text PIN field is :

• one nibble with the value of 0, which identifies this as a format 0 block
• one nibble encoding the length N of the PIN
• N nibbles, each encoding one PIN digit
• 14−N nibbles, each holding the Padding (cryptography)|fill value 15 (i.e. 1111 or F)

The account number field is:

• four nibbles with the value of zero
• 12 nibbles containing the right-most 12 digits of the primary account number(PAN), excluding the check digit

Extended PIN blocks

Formats 0 to 3 are all suitable for use with the Triple Data Encryption Algorithm, as they correspond to its 64-bit block size. However the standard allows for other encryption algorithms with larger block sizes, e.g. the Advanced Encryption Standard has a block size of 128 bits. In such cases the PIN must be encoding into an extended PIN block, the format of which is defined in a 2015 amendment to ISO 9564-1. In this library, we have used 3DES in ECB/NoPadding mode.

For better clarification please refer to the following online tool: https://neapay.com/online-tools/calculate-pin-block.html

Original Code

https://github.com/Carrene-Dev/cryptolib-java