Patent ID: 7802098

Claim:
A method of using cryptography for smart cards comprising: introducing into communication with a terminal, a smart card to perform a current transaction, the smart card comprising a central processing unit and being adapted to communicate with the terminal through an input-output interface; entering, by the smart card, into a waiting period wherein there is no active task related to an input-output event to be performed by the smart card for the current transaction; and performing, by the smart card, at least one cryptographic precomputation associated with a future transaction to be performed by the smart card, the future transaction being independent from the current transaction, the at least one cryptographic precomputation comprising a plurality of intermediate computations including at least partial calculation of one or more witness elements, wherein a result of each intermediate computation is stored in the smart card in a storage zone of the card, wherein the at least one cryptographic precomputation is performed by the smart card during the waiting period, and wherein one or more active tasks related to the current transaction have priority over the at least one cryptographic precomputation such that input-output events related to the one or more active tasks interrupt the at least one cryptographic precomputation thereby ending the waiting period.