This paper contributes to creating an unbreakable S-Box based on strong bent function expanded by DNA sequences and investigates and analyzes the strength of the proposed S-Box against major standard criteria and benchmarks such as interpolation attack, algebraic attack, avalanche effect, nonlinearity, and period. The outcome of the tests shows that the proposed S-box has good security, as well as it is passed all the randomness tests. On average, the results had after the tests applied have been come with SAC =0.50122, NL = 112, BIC =103.40625 and an iterative period with its maximum value = 256. The complexity of the proposed S-Box is increased with the getting algebraic expression of 255 terms which implies that the algebraic attack resistance = 2 160 . Based on the proposed S-Box, a candidate image enciphering scheme is also suggested to prove the strength of the S-Box. The analysis of the experiments that applied on two modes of images, gray images and RGB ones, supports the scheme's robustness against different differential and statical using standard criteria such as correlation coefficient analysis, information entropy, histogram analysis, unified average change intensity, number of pixels change rate and many others. This enforces the capability of using it in modern-day cryptosystems that utilized in multimedia data exchange.