An information processing device, information processing method and a recording medium are provided. Storage included in the information processing device is operable to store a node key and a leaf key, the leaf key being unique to the information processing device and the node key being unique to each node of a hierarchical network of nodes having a hierarchical tree structure. A decryption processor performs decryption processing to detect whether an encrypted decryption key for decrypting encrypted data is stored in at least one of on the information processing device or on a recording medium. When the encrypted decryption key is detected, the decryption processor is operable to calculate the decryption key by decrypting the encrypted decryption key. However, when the encrypted decryption key is not detected, the decryption processor is operable to calculate the decryption key by decrypting a key block using one of the one or more node keys stored in the storage and the leaf key stored in the storage. The calculated decryption key may then be encrypted and stored by the decryption processor on at least one of the recording medium or the memory.