With the migration of the economy and business contacts into the electronic sphere, the issue of time and confirming the credibility of documents is becoming increasingly important. When working with electronic documents, users often wonder who the author of a document is and when that document was actually created. The issue of document authorship is linked to an electronic signature, which, together with an electronic certificate, allows for the identification of the document’s author. There is no service yet that would allow for reading the creation date of a document in a reliable way; however, an electronic time stamping service for documents is available, which allows for reliably stating that a document of a given form existed at a given time. In business contacts, documents often need to be sent within a specific deadline so that the recipient of the shipment is sure that the document will not be changed later. Also in everyday life, when filing tax returns or issuing transfers, we receive confirmations from authorized persons that the documents that have been submitted will be received on time. In the case of administrative problems, having a timestamp confirms that the document was submitted within a specific deadline. In this way, one can avoid additional costs associated, for example, with paying penalty interest. Notarizing a date on a document is expensive and troublesome. Thanks to the use of electronic document dating, one can avoid costs, loss of time, and the incompetence of third parties. Electronic document dating improves the security of business processes by preventing the backdating of contracts, the preparation of documents with a retroactive date, making changes to documents after they have been time-stamped, denying participation in a transaction, etc., and furthermore, it supports the creation of electronic document registration systems. In 2001, the IETF organization published the RFC 3161 standard, providing the necessary concepts and schemes needed for electronic document dating. The operation of an electronic document dating system is very simple and consists of connecting the client application to a TSA (Time Stamping Authority) center and sending a document hash of a specific length, which is created after applying a hash function, e.g., MD5 (Message Digest, 128 bits), SHA-1 (Secure Hash Algorithm, 160 bits), or SHA-256 (Secure Hash Algorithm, 256 bits). It can therefore already be seen that the dated document is secure because no one at the authorization center will read its content. The hash of the document (or any file) undergoes verification of correctness and is then marked with the exact time and sent back to the client application.
The article comes from the magazine “e-Fakty” 5/2005.