Abstract
A convenient and inherently more secure communication channel for encoding messages via specifically designed molecular keys is introduced by combining advanced encryption standard cryptography with molecular steganography. The necessary molecular keys require large structural diversity, thus suggesting the application of multicomponent reactions. Herein, the Ugi four-component reaction of perfluorinated acids is utilized to establish an exemplary database consisting of 130 commercially available components. Considering all permutations, this combinatorial approach can unambiguously provide 500,000 molecular keys in only one synthetic procedure per key. The molecular keys are transferred nondigitally and concealed by either adsorption onto paper, coffee, tea or sugar as well as by dissolution in a perfume or in blood. Re-isolation and purification from these disguises is simplified by the perfluorinated sidechains of the molecular keys. High resolution tandem mass spectrometry can unequivocally determine the molecular structure and thus the identity of the key for a subsequent decryption of an encoded message.
Highlights
A convenient and inherently more secure communication channel for encoding messages via designed molecular keys is introduced by combining advanced encryption standard cryptography with molecular steganography
Ultimate security will never be reached, a constant progress and improvement of cryptography and steganography, both evolving with the needs and possibilities of new technologies on the one hand and the steady increase of the capabilities of adversaries on the other hand, is required
A core task of cryptography is encryption, i.e., to convert messages into unintelligible ciphertexts that can only be decrypted by a receiver who possesses a dedicated decryption key
Summary
The components chosen for this database are commercially available and selected in order to selectively react to the desired Ugi products (criteria listed in the Methods section and illustrated in Supplementary Figure 1) This set of 130 components can potentially be combined to 10 × 50 × 50 × 20 = 500,000 different molecular keys. The main function of the list of components is to assign chemical information (i.e., reacting components and side chains of the respective molecular keys) to alphanumerical codes (i.e., systematic combinations of letters, numbers, and special characters) For this purpose, a letter is given to a certain chemical functional group, and the different sidechains within the same category of functional groups are counted with arbitrary numbers, e.g., aldehydes → letter A, benzaldehyde → A(001), butyraldehyde → A (003), ...; isocyanides → letter B, ...). The transmitted keys can hardly be recognized, because (i) an adversary does not know that a key is hidden in a molecule; (ii) only the recipient knows where the molecular key is located/stored (i.e., adsorbed on paper, dissolved in perfume, etc., see below); (iii) information on
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