  In this paper a randomness evaluation of a block cipher for secure image
communication is presented. The GFHT cipher is a genetic algorithm, that
combines gene fusion (GF) and horizontal gene transfer (HGT) both inspired from
antibiotic resistance in bacteria. The symmetric encryption key is generated by
four pairs of chromosomes with multi-layer random sequences. The encryption
starts by a GF of the principal key-agent in a single block, then HGT performs
obfuscation where the genes are pixels and the chromosomes are the rows and
columns. A Salt extracted from the image hash-value is used to implement
one-time pad (OTP) scheme, hence a modification of one pixel generates a
different encryption key without changing the main passphrase or key.
Therefore, an extreme avalanche effect of 99% is achieved. Randomness
evaluation based on random matrix theory, power spectral density, avalanche
effect, 2D auto-correlation, pixels randomness tests and chi-square hypotheses
testing show that encrypted images adopt the statistical behavior of uniform
white noise; hence validating the theoretical model by experimental results.
Moreover, performance comparison with chaos-genetic ciphers shows the merit of
the GFHT algorithm.
