Time stamp is an encrypted voucher document, which is used to accurately record the generation time of electronic files. In other words, it can match a hash value, indicating that the file has not been tampered with since the time recorded by the timestamp. In electronic contracts, the sender's private key and hash value are usually encrypted together.

Time stamp includes three parts:

(1) Abstract); Time stamp of the file;

(2) Date and time when the time stamp service (DTS) received the file;

(3) Digital signature of Time Stamp Service (DTS);

(Schematic diagram of timestamp work)

Generally speaking, the process of time stamp generation is as follows: users first encrypt files that need time stamps with Hash codes to form abstracts, and then send the abstracts to DTS. DTS encrypts (digitally signs) the file after adding the date and time information of receiving the file summary, and then sends it back to the user.

The time when the document is signed in writing is written by the signer himself, but the digital time stamp is not. It was added by the authentication unit DTS according to the time when DTS received the document.

For example, a digital signature signed by a contract lock includes a valid timestamp issued by synchronizing a third-party valid time source with a timestamp certificate issued by SHECA. At this point, the user himself, even as a time stamp caller, can't forge or modify the time when the time stamp service is published.