A method for securing a contactless payment transaction performed by a mobile device on a payment terminal, the mobile device comprising a secure element configured to provide a token associated to a current payment transaction and to transmit the token to the payment terminal via a short-range wireless communication channel, the method is characterized in that it comprises steps of: - receiving from the payment terminal, by the mobile device, transaction parameters pertaining to the current payment transaction, - providing, by the mobile device, a unique initial token formed from at least part of the received transaction parameters, - transmitting, by the mobile device, to the payment terminal, via the short range wireless communication channel, a first token (T1 = TO x P1) resulting from a combination of the initial token and a first parameter specific to the mobile device by applying a reversible mathematical operation (x), - receiving from the payment terminal, in response to the first token, a second token (T2 = T1 x P2) resulting from a combination of the first token and a second parameter specific to the payment terminal by applying the reversible mathematical operation (x), - determining, by the mobile device, the second parameter (P2 = T2 / T1) from a combination of the second token and the first token by applying an inverse (/) of the reversible mathematical operation (x), - determining a mobile difference value (D1 = diff (P1, P2)) between the second parameter and the first parameter, - comparing the mobile difference value with a predetermined reference difference range (D1ref) stored in a memory of the mobile device, - if the mobile difference value is within the reference difference range (D1ref), transmitting to the payment terminal a third token (T3 = P1 x P2) obtained by a combination of the first parameter and the second parameter by applying the reversible mathematical operation (x), - determining by the payment terminal the first parameter (P1 = T3 / P2) from a combination of the third token and the second parameter by applying the inverse (/) of the reversible mathematical operation (x), - determining by the payment terminal a terminal difference value (D2 = diff (P1, P2)) between the second parameter and the first parameter, - comparing the terminal difference value with a predetermined reference difference range (Dref2) stored in a memory of the payment terminal, - if the terminal difference value is comprised within the reference difference range (D2ref), determining the initial token (TO = T2 / T3) from a combination of the second token and the third token by applying the inverse (/) of the reversible mathematical operation (x), - transmitting by the payment terminal the determined initial token to a server of a payment authority, the payment transaction being processed by the payment terminal, characterized in that the first parameter and the second parameter represent position coordinates respectively of the mobile device and the payment terminal, the position coordinates being determined by a global positioning system or by an indoor positioning system. - receiving from the payment terminal, by the mobile device, transaction parameters pertaining to the current payment transaction, - providing, by the mobile device, a unique initial token formed from at least part of the received transaction parameters, - transmitting, by the mobile device, to the payment terminal, via the short range wireless communication channel, a first token (T1 = TO x P1) resulting from a combination of the initial token and a first parameter specific to the mobile device by applying a reversible mathematical operation (x), - receiving from the payment terminal, in response to the first token, a second token (T2 = T1 x P2) resulting from a combination of the first token and a second parameter specific to the payment terminal by applying the reversible mathematical operation (x), - determining, by the mobile device, the second parameter (P2 = T2 / T1) from a combination of the second token and the first token by applying an inverse (/) of the reversible mathematical operation (x), - determining a mobile difference value (D1 = diff (P1, P2)) between the second parameter and the first parameter, - comparing the mobile difference value with a predetermined reference difference range (D1ref) stored in a memory of the mobile device, - if the mobile difference value is within the reference difference range (D1ref), transmitting to the payment terminal a third token (T3 = P1 x P2) obtained by a combination of the first parameter and the second parameter by applying the reversible mathematical operation (x), - determining by the payment terminal the first parameter (P1 = T3 / P2) from a combination of the third token and the second parameter by applying the inverse (/) of the reversible mathematical operation (x), - determining by the payment terminal a terminal difference value (D2 = diff (P1, P2)) between the second parameter and the first parameter, - comparing the terminal difference value with a predetermined reference difference range (Dref2) stored in a memory of the payment terminal, - if the terminal difference value is comprised within the reference difference range (D2ref), determining the initial token (TO = T2 / T3) from a combination of the second token and the third token by applying the inverse (/) of the reversible mathematical operation (x), - transmitting by the payment terminal the determined initial token to a server of a payment authority, the payment transaction being processed by the payment terminal,