The present invention relates to a method which aims to improve data security in mobile payment transactions. To achieve this goal, we propose a highly secure method for transactions validation through video encryption and a new view of secrecy based on the combination of encrypted video (102, 203, 305) and a transparent safe card (110, 202, 307) with unique secret pattern (111, 308). This safe card (110, 202, 307) is shown as a translucent or transparent device capable of acting as “layer” or decoding mask using visual cryptography techniques. Additionally, it is proposed in one embodiment of the present invention a method for encryption of unencrypted video (602) through a frame analysis module (601) and a frame recomposition module (612).