The present invention relates to an information processing apparatus, an information processing method, a program, and a recording medium for sending and receiving data in a manner enhancing security. A host and a drive unit are interconnected by a suitable bus and exchange data over that bus. The host requests the drive unit periodically to issue an initializing vector IV for use in encrypting and decrypting the data exchanged over the bus. The drive unit supplies the initializing vector IV to the host on request. If these steps are not carried out periodically, the drive unit stops outputting data to the host. The present invention is adapted advantageously to personal computers equipped with a drive unit for reproducing data from a recording medium.