The rapid development of information technology has been totally changed a conventional trading system. With convention trading system is meant that papers and signature are important substances and uses as authentic proven of a trading transaction, whilst in the case of electronic commerce is meant that documents and massages sent by electronic mail or website are used as legal basis as authentic proven of a trading transaction. Therefore, electronic information in the e-com became an important substance of legal ground of trading transaction. The Information and Electronic Transaction Law No. 11 year 2008 declares that electronic information and/or electronic document and/or the print-out of electronic information have become a valid avident for legal proven. The question is how to know technically that the documents of electronic information are proven as authentic document in the legal point of view. There are at least five eminent requisites for proving electronic document such as, authenticity, integrity, reliability, secrecy, and genuiness/originality of the electronic information.