A method, computer program product, and data processing system for generating and validating an upgradeable digital timestamp of a document is disclosed. The digital timestamp includes a hash value, a current time, and a digital signature. Over time, as computer and cryptanalytic technology progresses, upgrade timestamps are applied to the document that take advantage of more advanced, more difficult to break hash functions or digital signature schemes. These upgrade timestamps are applied preventatively at a point in time just prior to the timestamp's being able to be compromised.