Abstract: Molecular anti-counterfeiting taggants are made from a plurality of synthetic polynucleotides that collectively encode a bit sequence using the sequences and hybridization states of the polynucleotides. The polynucleotide taggant is placed on an item as a molecular identifier of authenticity. The bit sequence encoded by the polynucleotide taggant is read out using a substrate which has bound polynucleotides complexes that hybridize with the synthetic polynucleotides in the polynucleotide taggant. A detectable signal is present where hybridization occurs. To prevent a bad actor from reverse engineering and creating a copy of the polynucleotide taggant using the results of hybridization to the substrate, multiple versions of the substrate are created. Each version hybridizes to different subsets of the synthetic polynucleotides in the polynucleotide taggant. A detectable pattern on the substrate that is present when exposed to the polynucleotide taggant is used for validating authenticity of the item.

Abstract: Molecular taggants are used to label items with binary barcodes. Molecular taggants may use presence encoding with the presence or absence of a particular molecule representing a 0 or 1. Molecular taggants may alternatively use hybridization encoding where the hybridization of a second strand to a polynucleotide represents a 0 or 1. If multiple such molecular taggants are combined, this leads to a bitwise OR operation that may make it impossible to correctly identify the original binary barcodes. To address this problem, superimposed encoding is applied to the design of the binary barcodes. The superimposed encoding identifies a set of valid binary barcodes that can be uniquely identified from a sample comprising a mixture molecular taggants. One way of doing this is to generate a Hadamard matrix and use the values of entries in the matrix as one of the binary barcodes.

Abstract: Molecular anti-counterfeiting taggants are made from a plurality of synthetic polynucleotides that collectively encode a bit sequence using the sequences and hybridization states of the polynucleotides. The polynucleotide taggant is placed on an item as a molecular identifier of authenticity. The bit sequence encoded by the polynucleotide taggant is read out using a substrate which has bound polynucleotides complexes that hybridize with the synthetic polynucleotides in the polynucleotide taggant. A detectable signal is present where hybridization occurs. To prevent a bad actor from reverse engineering and creating a copy of the polynucleotide taggant using the results of hybridization to the substrate, multiple versions of the substrate are created. Each version hybridizes to different subsets of the synthetic polynucleotides in the polynucleotide taggant. A detectable pattern on the substrate that is present when exposed to the polynucleotide taggant is used for validating authenticity of the item.