{'fraction_non_alphanumeric': 0.020606060606060607, 'fraction_numerical': 0.0, 'mean_word_length': 5.3538461538461535, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Keyless asynchronous covert communication

We consider a scenario in which Alice asynchronously communicates with Bob over a Discrete Memoryless Channel (DMC) while escaping detection from an adversary who observes their communication through another DMC. Specifically, Alice transmits codewords of length n and chooses the transmission epoch T uniformly at random among N available time epochs, where N ≫ n. This deliberate symbol level-asynchronism forces the adversary to monitor a window of size N' much larger than the codeword length n, and results in an increased covert throughput compared to the scenario without asynchronism. Our result generalizes a previous work in which asynchronism was introduced at the codeword level, i.e., having Alice choose a transmission window among non-overlapping windows of length n.