Cryptomathic Blog

Cardholders (or consumers) are one of the corners of the ‘four corner’ model in the payment card world. Here we take a brief look at the payment security in relation to cardholders.

A key block is a unique cryptographic structure designed to protect cryptographic keys during transport over potentially insecure networks. A team around Mohammed M Atalla invented the concept of the key block with his Atalla key block. This solved several issues created by “key variants” that were then used for transporting keys.

Among all the various key block formats, the TR-34 format is undoubtedly one of the most sophisticated formats.

The TR-34 norm is an implementation of the X9.24-2 norm. It proposes a realistic and efficient way of exchanging symmetric keys using asymmetric cryptography. This is basically a certificate-based Remote Key Loading (RKL) protocol. 

This article proposes answers to a series of frequently asked questions (FAQs) about key blocks.

One aspect of key management is dealing with what happens when a symmetric cryptographic key is no longer needed. The section ‘Key Replacement, Destruction and Archiving’ within ANSI X9.24-1-2017 explains what needs to happen.

The “Four Corners'' model, also called the Four Party Scheme, is utilized in almost all standard card payment systems across the globe. Here we introduce that model and explain what type of hardware security module (HSM) is needed for each of its components involved in the cryptographic process.

In a retail financial services environment, the compromise of a symmetric cryptographic key is a critical security breach. Such a situation is described by the ANSI X9.24-1-2017 standard. Here, we summarize the ANSI guidance on how to respond if a potential compromise has been identified.

The PCI Council requires most actors of payment networks to implement ANSI X9.24/TR-31-compliant key blocks to wrap and securely transmit, transfer, or translate key or PIN codes.

This article briefly summarizes the symmetric cryptographic key utilization and storage requirements as described by the ANSI X9.24-1-2017 (part 1) standard.