Method for secure data exchange between two devices

Data exchange method between two devices locally connected to one another, especially between a security module and a receiver, the first device comprising at least one first encrypting key of a pair of asymmetric keys and the second device comprising at least the second encrypting key of said pair of asymmetric keys, these keys being previously initialised in the first and second device, this method comprising:

• generating, at least one first random number in the first device,
• generating, at least one second random number in the second device,
• encrypting said first random number by said first encrypting key,
• encrypting said second random number by said second encrypting key,
• transmitting said first encrypted random number to the second device,
• transmitting said second encrypted random number to the first device,
• decrypting the first encrypted random number in said second device,
• decrypting the second encrypted random number in said first device,
• combining said random numbers generated by one of the devices and received by the other device to generate a session key,
• and using the session key to encrypt and decrypt all or part of the exchanged data between the first and second device.