HANDLING A SECRET KEY

摘要

The present invention relates to a device comprising: a processor (1) controlling the operation of the device, a memory (M) connected to the processor (1) through a bus (5), and an auxiliary processor (9) connected to the processor (1) and the memory (M) through said bus (5) in order to produce a response on the basis of a secret key (K). In order to make it even more difficult for an external attacker to find out the secret key, said secret key (K) is stored encoded (K') in said memory (M). Calculating means (8) of the auxiliary processor (9) comprise a decoding function for calculating the secret key (K) from the encoded secret key (K') in a data register (R2), and a calculating function of the calculating means (8) retrieves the decoded secret key (K) in order to produce said response.