With over 250 sub-requirements, the PCI DSS can be sorted at a high level into 6 goals and 12 main requirements.
SIX GOALS, TWELVE REQUIREMENTS
The Payment Application Data Security Standard (PA-DSS) is for software developers and integrators of payment applications that store, process or transmit cardholder data as part of authorization or settlement when these applications are sold, distributed or licensed to third parties.
PA-DSS requires vendors of third-party payment applications to ensure proper security controls are in place to safeguard cardholder data. Many of the controls within PA-DSS are designed to specifically address common vulnerabilities that were identified as main causes in credit card data loss.
Mastercard requires all merchants and service providers that use third party-provided payment applications to use only those applications that are compliant with the PCI PA-DSS, as applicable. The applicability of the PCI PA-DSS to third party provided payment applications is defined in the PCI PA-DSS Program Guide available on the PCI Security Standards Council (SSC) website.
Mastercard also recommends that merchants use a Qualified Integrator & Reseller (QIR) listed on the PCI SSC website to implement a PCI PA DSS–compliant payment application.