- Abdullah Al-Shamim
The Public Key Infrastructure (PKI) is an infrastructure that includes man, machine and a set of guidelines to issue, manage, distribute and use Public Key certificates owned by the PKI entities. It also plays a significant role in authenticating a chip card by its Issuer.
Two different cryptographic mechanisms are used in a payment system—Symmetric and Asymmetric. When cryptographic request is generated by the chip card and authenticated by the Issuer (online), symmetric mechanism is used. To contrary, in case of asymmetric cryptography, the cryptographic request is authenticated locally through the terminal on behalf of the Issuer.
In payment ecosystem, the payment scheme (e.g. Visa, Mastercard), Issuer and the chip card got key pair ownership. These Private Key entities follow a hierarchical structure for issuance and maintenance of Public Key certificates. The payment scheme plays the role of Certification Authority (CA) that issues certificate for the Issuer and Issuer issues Public Key certificates for the chip card.
CA key pair is generated by the payment system in a secure way, commonly in a secure environment and application by using a hardware security module (HSM). Payment System CA distributes newly generated CA Public Keys to its member Issuers and Acquirers. Issuer needs it to verify Issuer Public Key Certificates generated by the Payment System CA during the key usage phase, and Acquirer requires them for secure loading of the CA Public Keys in its merchant terminals.
According to EMV, PKI is involved in two different offline processing steps in a payment transaction—one is offline PIN verification and another is offline data authentication. These two steps are highly recommended if Issuer supports offline transaction. In an offline transaction, Issuer has no way to verify the card content and that is why it uses its Public Key along with the ICC Public Key to verify an offline PIN and statically (known as Static Data Authentication—SDA) or dynamically (known as Dynamic Data Authentication—DDA or Combined Data Authentication—CDA) generated digital signature to make sure the authenticity of the card.
Kona Software Lab Ltd., the Bangladesh office of the South Korean payment and security industry pioneer Kona I Co., Ltd., is leading the chip card implementation in Bangladesh with the largest market share. With more than two decades of experience in card manufacture and numerous product certifications from various payment schemes, Kona group adds unique value to its more than 500 clients in almost 90 countries all over the world and helps them solidify their security considerations. The company also provides consultation in EMV migration, local scheme, card and terminal testing, and so forth; and wishes to continue it to help the players in the local payment and security industry in Bangladesh to reach their desired goal.
The author is a Payment and Security Specialist, Kona Software Lab Ltd.