A data processing device comprising: - encryption means (101) configured to encrypt control data (L1) resulting in encrypted control data (Ksig(s)); - padding means (21) configured to pad encrypted control data (Ksig(s)) with zero padding bits resulting in post-padding encrypted control data (Kbch) to set a data length of the data (Ksig( s)) control data encrypted to a target data length of a BCH error correction encoding, control data (L1) to be used for demodulation; - error correction coding means (22) configured to perform error correction coding on the encrypted post-padding control data (Kbch) by adding BCH code parity bits to the end of the encrypted post-padding control data (Kbch) , thus obtaining the bits (Kldpc) of the BCH code; - LDPC correction encoding means (23) configured to add LDPC code parity bits after the BCH code parity bits of the BCH code bits (Kldpc), to obtain the LDPC code bits (Nldpc), - shortening means (24) configured to puncture the LDPC code parity bits of the LDPC code bits (Nldpc) and remove the zero padding bits from the LDPC code bits (Nldpc), to obtain the data (Npost) post-shortening LDPC code for transmission, punctured parity bits and zero padding bits not being transmitted; and - a frame constructor (27) for creating a frame containing the post-shortening LDPC code data (Npost) and multiplexing the frame into a DVB-T2 signal for transmission with one or more other frames, wherein the frame contains a preamble, which preamble includes a symbol including information identifying that the frame comprises the post-shortening LDPC code data (Npost) containing the encrypted control data (Ksig(s)).