Quotable Signatures for Authenticating Shared Quotes
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Quotable signatures are digital signatures that allow a user to quote parts of a signed document, permitting a reader of the quote to verify its authenticity. This paper adds to the theory on quotable signatures in three ways: (1) by giving bounds on the size of signatures for arbitrary and contiguous quotes, when the quotable signatures are realized using Merkle trees, (2) by proving the security of quotable signature realized using Merkle trees, and (3) by providing algorithms for signing, quoting, and verifying quotable signatures realized using Merkle trees. Additionally, the paper carefully considers a concrete use case of quotable signatures, using them to combat misinformation by bolstering authentic content. Motivation is given for why using quotable signatures could help mitigate the effects of fake news.
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