I have a debit payment card, once it expired I received a new one. The card numbers look like this
Old card xxxx xxxx 1111 1111
New card xxxx xxxx 2222 2222
where x are the matching numbers and 1 and 2 are different (odd, but maybe the first 8 numbers are assigned to the particular bank/branch which I didn't change).
Now, the card security code according to Wikipedia is
[...] is calculated by encrypting the bank card number, expiration date and service code with encryption keys known only to the card issuer, and decimalising the result.
But my new code only incremented by one. Example:
Old CSC: 111
New CSC: 112
This could be by pure chance (1 in 1000), but what if it's not.
Question: Is it a real increment of CSC for a replacement card or coincidence? If it's increment - is it bad?