Abstract: The system comprises a sending entity (100) and a receiving entity (200). The sending entity (100) is suitable for generating a random mask (MA) with m bits; applying an XOR operation between the raw data block to be encrypted (T) and the random mask (MA) thus generated to obtain a primary encrypted block (CPV) with m bits; and applying a permutation (PE) on the concatenation of the random mask (MA) and the primary encrypted block (CPV) to obtain a secondary encrypted block (CS). The receiving entity (200) is suitable for receiving the secondary encrypted block (CS) of 2*m bits; applying an inverse permutation (PI) on the secondary encrypted block thus received to obtain the de-concatenation of a random mask (MA) and a primary encrypted block (CPV) with m bits; and applying an XOR operation between the primary encrypted block (CPV) and the random mask (MA) thus de-concatenated to obtain a block in clear (T) with m bits.