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Cryptographic time

Is there a cryptographic mechanism by which you can sign a document with a date, so that it is impossible to fake the same signature later? Maybe some server that publishes daily cryptographic keys (but how can you trust them? ;-).

For the inevitable pragmatists of pushing, I'm not trying to accomplish any task. I'm just wondering what a decision space is.

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2 answers

This is called Timestamping (TSP protocol, RFC 3161 ). Various digital signature standards (PDF and XML signatures, CAdES, PAdES, XAdES) include support for extended timestamps based on TSP.

MS Authenticode also includes a time reference, but uses a different (incompatible and less secure) mechanism for this.

Only TSP (without signature protocols) is not used much, but in combination with signature standards it is very convenient.

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GuardTime has an interesting service where the time stamp is independent of a trusted third party ("signed time"), but can be independently verified by any interested party. It works in much the same way as hash tree based bitcoins.

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Source: https://habr.com/ru/post/891610/

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