I have been thinking about digitally signed documents (Word files and PDF files) and can not get over the fact about - how can I securely know when the file was signed? Scenario: If the date of the ...
Does there currently exist a free online service that accepts a file, hashes it, takes an authoritatively chosen timestamp (from one or more time services), signs these and sends this signed message ...
Let's say A wants to send a message, so everyone who gets the message, can be assured that it's from A. A then sends a message ...
I have a PDF document intended for long-term (many years, maybe decades) archival which I would like to digitally sign with my personal certificate to ensure its integrity. As far as I understand, I ...
You put an input and the hash value comes as an output then when someone puts the input the hash function it is applied to see if it is the same hash original value is stored in some database , that ...
PGP/GPG can used to sign text, others use public key to verify them. So one could say, that these cryptographic algorithms deal with space. Are there any algorithms that can deal with time? E.g. I ...