Patent ID: 7822203

Claim:
An information processing apparatus configured to decrypt, using meta data, encrypted data obtained by encrypting stream data including a plurality of successive units of data according to a first encryption method in which, when the stream data is sequentially encrypted on a unit-by-unit basis, each of a plurality of keys used for encrypting a corresponding one of the units of data is updated on the basis of a predetermined rule, the meta data including the plurality of keys used for encrypting the stream data and update information for identifying update timings of the plurality of keys, the apparatus comprising: a decrypter configured to acquire the encrypted data and decrypt each of the units of data in the encrypted data using the key used for encrypting the unit of data among the plurality of keys; and a meta data acquirer configured to acquire the meta data and deliver one of the plurality of keys contained in the meta data that corresponds to the unit of data to the decrypter in accordance with the update information contained in the meta data, the meta data acquirer including, a first corrector configured to determine whether an error has occurred in the acquired update information identifying the update timings of the plurality of keys, and when it is determined that an error has occurred in the acquired update information, to correct at least part of the update information that has been acquired by issuing a command to change the update timing of at least one of the plurality of keys, the command being issued when a result of a comparison of a first update information value related to a target unit of data, which is to be decrypted by the at least one of the plurality of keys for which the command is issued, to a second update information value related to a preceding unit of data is in accordance with a predetermined transition pattern.