Certification path validation algorithm: Difference between revisions

Revision as of 08:06, 2 August 2017

Revision as of 02:12, 20 April 2018

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* Name constraints are checked, to make sure the subject name is within the permitted subtrees list of all previous CA certificates and not within the excluded subtrees list of any previous CA certificate;

* The asserted [[certificate policy]] [[object identifier|OIDs]] are checked against the permissible OIDs as of the previous certificate, including any policy mapping equivalencies asserted by the previous certificate;

* Policy constraints and basic constraints are checked, to ensure that any explicit policy requirements are not violated and that the certificate is a CA certificate, respectively. This step is crucial in preventing some [[man in the middle attacksattack]]s;<ref>Moxie Marlinspike, [https://www.blackhat.com/presentations/bh-dc-09/Marlinspike/BlackHat-DC-09-Marlinspike-Defeating-SSL.pdf New Tricks For Defeating SSL In Practice], [[Black Hat Briefings|Black Hat]] DC Briefings 2009 conference.</ref>

* The path length is checked to ensure that it does not exceed any maximum path length asserted in this or a previous certificate;

* The key usage extension is checked to ensure that is allowed to sign certificates; and