Checking the timestamp Trusted timestamping

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checking correctness of timestamp generated time stamping authority (tsa)


anyone trusting timestamper can verify document not created after date timestamper vouches. can no longer repudiated requester of timestamp in possession of original data @ time given timestamp. prove (see diagram) hash of original data calculated, timestamp given tsa appended , hash of result of concatenation calculated, call hash a.


then digital signature of tsa needs validated. can done checking signed hash provided tsa indeed signed private key digital signature verification. hash compared hash b inside signed tsa message confirm equal, proving timestamp , message unaltered , issued tsa. if not, either timestamp altered or timestamp not issued tsa.







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