Opportunities to improve the effectiveness of associative protection in scene analysis can be found in changing the configurations of digital etalons (reference patterns) and in transition from a decimal to a hexadecimal system when encoding object names and their coordinates. The relevance of the research undertaken is determined by the need for a significant increase in the number of keys used and the advisability of further improvement of the security strength. Based on a preliminary analysis, a rule for selecting digital reference configurations has been formulated from the condition of uniform distribution of bit inclusions in the pseudorandom sequence (GAMMA) container when using the decimal and hexadecimal systems for encoding purposes. Algorithms for forming a complete and limited test list of permutations for experimental research purposes have been developed. Results of the computational experiment confirmed validity of the formulated rule. For the accepted configurations, estimates of the expected number of preserved bits of the etalon were obtained.