A data processing system includes: a stream decoder for decrypting a stream encrypted by broadcast encryption to obtain a first decrypted stream; an internal buffer for storing the first decrypted stream; and an encryption/decryption processor. The encryption/decryption processor decrypts a stream encrypted by content encryption to obtain a second decrypted stream and storing the second decrypted stream in the internal buffer, and reads one of the first and second decrypted streams from the internal buffer and encrypts the read-out stream by content encryption.