A method for performing a payment transaction, the method comprising: - receiving a secret (SYK2) for a payment application from an operator's server system to a user's terminal in response to a successful login to said server system , - activating a trust card in said user's terminal by utilizing said secret (SYK2) for the payment application, said trust card being a virtual trust card comprising an application for controlling access to said payment application, an encryption algorithm and keys for encryption of the payment algorithm, and said activating comprising using said secret (SYK2) for the payment application to set said trust card into a mode where said trust card can communicate with external parties in addition to said server system, - receiving payment data from a point-of-sale terminal at the user's terminal , said payment data relating to said payment transaction, - transmitting said payment data to the operator's server system to be verified, said payment data being transmitted in encrypted form encrypted by said secret (SYK2) for said payment application, characterised by - receiving a second secret (SS2) at the user's terminal , said second secret (SS2) having been formed by the operator's server system if said verification of said payment data produces an acceptable result, said second secret (SS2) being configured to be used for performing said payment transaction, said second secret (SS2) being received in encrypted form encrypted by said secret (SYK2) for said payment application, and - transmitting data of the trust card and a combination of a user's secret (SS1) and said second secret (SS2) from said user's terminal to said point-of-sale terminal for checking and performing the payment transaction through the point-of-sale terminal . - receiving a secret (SYK2) for a payment application from an operator's server system to a user's terminal in response to a successful login to said server system , - activating a trust card in said user's terminal by utilizing said secret (SYK2) for the payment application, said trust card being a virtual trust card comprising an application for controlling access to said payment application, an encryption algorithm and keys for encryption of the payment algorithm, and said activating comprising using said secret (SYK2) for the payment application to set said trust card into a mode where said trust card can communicate with external parties in addition to said server system, - receiving payment data from a point-of-sale terminal at the user's terminal , said payment data relating to said payment transaction, - transmitting said payment data to the operator's server system to be verified, said payment data being transmitted in encrypted form encrypted by said secret (SYK2) for said payment application, characterised by - receiving a second secret (SS2) at the user's terminal , said second secret (SS2) having been formed by the operator's server system if said verification of said payment data produces an acceptable result, said second secret (SS2) being configured to be used for performing said payment transaction, said second secret (SS2) being received in encrypted form encrypted by said secret (SYK2) for said payment application, and - transmitting data of the trust card and a combination of a user's secret (SS1) and said second secret (SS2) from said user's terminal to said point-of-sale terminal for checking and performing the payment transaction through the point-of-sale terminal . <EOS>