Abstract
We propose in this paper to reuse the existing payment infrastructure to introduce a proof of transaction genuineness computed by a smart card chip. The idea is to divide the amount of the transaction into several sub-amounts, which added together give the total amount. The sub-amounts are function of a secret shared with the bank, which can verify that the split is correct, thus proving that the transaction is authentic. We provide here a description of the algorithm and its implementation in a .NET card.