A method of processing broadcast data includes: receiving a broadcast signal including a group including mobile service data, FIC data, TPC data and known data sequences; demodulating the broadcast signal; compensating channel distortion generated in the demodulated broadcast signal based upon at least one of the known data sequences; decoding the FIC data and the TPC data from the channel distortion compensated broadcast signal; extracting the signaling information table from the channel distortion compensated broadcast signal; identifying a stream where keys to decrypt the mobile service data are obtained using the extracted signaling information table; and decrypting the mobile service data using the keys. The group further includes data blocks. First, fourth, fifth and sixth known data sequences are inserted into third, fifth, sixth and seventh data blocks, respectively. Second and third known data sequences are inserted into a fourth data block.