(26)In order to safeguard the confidentiality and the integrity of data, it is necessary to ensure the security of communication sessions between account servicing payment service providers, account information service providers, payment initiation service providers and payment service providers issuing card-based payment instruments. It is in particular necessary to require that secure encryption is applied between account information service providers, payment initiation service providers, payment service providers issuing card-based payment instruments and account servicing payment service providers when exchanging data.