Processing method and apparatus for encrypted data transfer

摘要

The present invention provides a data processing method and apparatus capable of shortening the processing time required when editing previously encrypted track data. An example of a transfer of audio track data between a portable player and a storage device is provided. The track data is comprised of one or more parts, each of which in turn is comprised of a series of data blocks. Each block of the track data is encrypted prior to transfer using a block key. The block keys are determined in such a manner that subsequent editing of the track data which results in redistribution of the parts does not require full decryption of the data.