In financial cryptography and PCI standards, a Key Block is an encrypted key stored with its metadata in a cryptographically secure way. That means that the key’s usage information and other parameters can’t be altered by an attacker by tampering with the encrypted key.
To understand why they are useful, and why their adoption is now a big deal in the financial services industry, we have to look at a little history.
A Brief History of PINs
We all have experience of using PIN codes at ATMs (cash machines) to authenticate ourselves to our bank and withdraw money. How does the issuing bank check we used the correct PIN? Likely we would imagine all the customer PINs being stored hashed in a database, somewhat like passwords, but in fact for historical reasons the system is quite different.