Reproducing hash values from printed documents to validate with a blockchain

A system and method are disclosed for rendering printed documents tamper evident. Examples render classes of documents tamper evident with cryptographic level security or detect tampering events, where such security was previously unavailable, for example, in documents printed using common printers without special paper or ink. Examples enable proving the date of document content without the need for expensive third party archival, including documents held, since their creation, entirely in secrecy or in untrustworthy environments, such as on easily-altered, publicly-accessible internet sites. Examples can use a document's prior registration date in a blockchain to establish a no-later than date-of-existence for that document. Examples can extend the useful life of integrity verification algorithms, such as hash functions, even when applied to binary executable files. Examples can efficiently identify whether multiple document versions are substantially similar, even if they are not identical, thus potentially reducing storage space requirements.