Data sequence randomization encryption system such that having supplied data sequence (X) and randomization-encryption key (Kp) generates random data sequence (Yp), so that laypersons in encryption are able to measure objectively the diffusion and confusion of the generated sequence (Yp) with the particular randomization-encryption key (Kp) which has been used. Data sequence (X) is divided into blocks (XI), each block (XI) gets into group with transformer block (WTI), generated by transformer block generator (1002) by making use of control initial block (R) and previous output block (YI), resulting in grouped block (VI), result of the group, which is encrypted by means of the device in U.S. Pat. No. 5,214,703 (204), generating output block (YI) which is supplied to transformer block generator (1002), the succession of output blocks (YI) results in output randomized-encrypted sequence (Yp).