Difference between revisions of "X.509 Certificate"

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Revision as of 08:39, 28 July 2018

Full Name or Meme

A structure defined by the CCITT (now ITU-T) that binds a Subject name to a public key and a set of Attributes.


  • Up until the 1970's the Postal and Telecommunications Agencies of the world governments just knew that they were responsible for assigning names and numbers to everything on the planet.
  • At that time only a few of the world governments, like the US, had placed the responsibilities for such naming and numbering in private hands.
  • Still in the US AT&T acted with the impunity of a government agency, until they were challenged in court by companies like MCI.
  • With all of the arrogance of a government body, the ITU's Committee on Communications and International Telephone and Telegraph (CCITT), decided to specifiy the structure of email and the corresponding security.


  • The result was an exceeding ugly encoding of everything they touched, most of which has faded into history, except the X.509 certificate structure.
  • The security at the time was based on the paradigm at the time - the credit card industry and the card revocation lists, which were updated every few weeks and needed to be checked by every merchant for every transaction.


  • At least now the certificates can be checked online and no longer require certificate revocation lists, although the specification still exists.
  • The content of a Web Site certificate is reasonably well defined[1] which makes them still useful for that purpose.
  • They can be used in other venues such as a digital assertion of the existence of some credential, like the ability to prescribe drugs, or to sign a digital document as an agent of some real-world entity.
  • On the web a new standard has evolved, the Json Web Token.


  1. DigiCert. What extensions and details are included in a SSL certificate? https://knowledge.digicert.com/solution/SO18140.html