Extended Validation Certificate

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Extended Validation Certificates (EV)[1] are a special type of X.509 certificate which requires more extensive investigation of the requesting entity[2] by the Certificate Authority before being issued.

The criteria for issuing EV certificates are defined by the Guidelines for Extended Validation Certificates, currently at version 1.1. The guidelines[3] are produced by the CA/Browser Forum, a voluntary organization whose members include leading CAs and vendors of Internet software, as well as representatives from the legal and audit professions[4].


[edit] Motivation

An important motivation for using digital certificates with SSL was to add trust to online transactions by requiring website operators to undergo vetting with a certificate authority (CA) in order to get an SSL certificate. However, commercial pressures have led some CAs to introduce "domain validation only" SSL certificates for which minimal verification is performed of the details in the certificate.

Most browsers' user interfaces did not clearly differentiate between low-validation certificates and those that have undergone more rigorous vetting. Since any successful SSL connection causes the padlock icon to appear, users are not likely to be aware of whether the website owner has been validated or not. As a result, fraudsters (including phishing websites) have started to use SSL to add credibility to their websites.

By establishing stricter issuing criteria and requiring consistent application of those criteria by all participating CAs, EV SSL certificates are intended to restore confidence among users that a website operator is a legally established business or organization with a verifiable identity.

[edit] Issuing criteria

Only CAs who pass an independent audit as part of their WebTrust (or equivalent) review may offer EV, and all CAs globally must follow the same detailed issuance requirements which aim to:

  • Establish the legal identity as well as the operational and physical presence of website owner;
  • Establish that the applicant is the domain name owner or has exclusive control over the domain name; and
  • Confirm the identity and authority of the individuals acting for the website owner, and that documents pertaining to legal obligations are signed by an authorised officer.

[edit] User interface

Browsers with EV support display more information for EV certificates than for previous SSL certificates. Microsoft Internet Explorer 7, Mozilla Firefox 3, Safari 3.2, Opera 9.5, and Google Chrome all provide EV support.

Example of the Extended Validation UI in Firefox 3 (note the address bar no longer turns yellow to indicate a secure connection)

The Extended Validation (EV) guidelines require participating Certificate Authorities to assign a specific EV identifier, which is registered with the browser vendors who support EV once the Certificate Authority has completed an independent audit and met other criteria. The browser matches the EV identifier in the SSL certificate with the one it has registered for the CA in question: if they match, and the certificate is verified as current, the SSL certificate receives the enhanced EV display in the browser's user interface.

[edit] Extended Validation certificate identification

EV certificates are standard x.509 digital certificates. The primary way to identify an EV certificate is by referencing the Certificate Policies extension field. Each issuer uses a different object identifier (OID) in this field to identify their EV certificates, and each OID is documented in the issuer's Certification Practice Statement.

Issuer OID Certification Practice Statement
Comodo Comodo EV CPS, p. 28
Cybertrust Cybertrust CPS v.5.2, p. 20
DigiCert 2.16.840.1.114412.2.1 DigiCert EV CPS v. 1.0.3, p. 56
DigiNotar 2.16.528.1.1001.1.1.1 DigiNotar CPS v 3.5, p. 17
Entrust 2.16.840.1.114028.10.1.2 Entrust EV CPS, p. 37
GeoTrust GeoTrust EV CPS v. 2.6, p. 28
GlobalSign GlobalSign EV CPS v. 6, p.22
Go Daddy 2.16.840.1.114413. Go Daddy EV CPS v. 2.0, p.42
Network Solutions Network Solutions EV CPS v. 1.1, 2.4.1
QuoVadis QuoVadis Root CA2 CP/CPS, p.34
SECOM Trust Systems 1.2.392.200091.100.731.1 SECOM Trust Systems EV CPS (in Japanese), p.2
Starfield Technologies 2.16.840.1.114414. Starfield EV CPS v. 2.0, p.42
SwissSign 2.16.756. SwissSign Gold CA-G2 CP/CPS, p.7
Thawte 2.16.840.1.113733. Thawte EV CPS v. 3.3, p.95
Trustwave* 2.16.840.1.114404. SecureTrust EV CPS v1.1.1, p.5
VeriSign 2.16.840.1.113733. VeriSign EV CPS v. 3.3, p.87

* "XRamp Security Services, Inc.", successor to SecureTrust corporation a wholly owned subsidiary of Trustwave Holdings,Inc. ("Trustwave")

[edit] Online Certificate Status Protocol

The criteria for issuing Extended Validation certificates do not require issuing Certificate Authorities to immediately support Online Certificate Status Protocol for revocation checking. However, the requirement for a timely response to revocation checks by the browser has prompted most Certificate Authorities that had not previously done so to implement OCSP support. Section 26-A of the issuing criteria requires CAs to support OCSP checking for all certificates issued after Dec. 31, 2010.

[edit] Surrounding issues

[edit] Availability to small businesses

Since EV certificates are being promoted[5] and reported[6] as a mark of a trustworthy website, some small business owners have voiced concerns[7] that EV certificates give undue advantage to large businesses.

The published drafts of the EV Guidelines excluded unincorporated business entities, and early media reports[7] focused on that issue. Version 1.0 of the EV Guidelines was revised to embrace unincorporated associations as long as they were registered with a recognized agency, greatly expanding the number of organizations that qualified for an Extended Validation Certificate.

Early media reports also focused on the higher price of EV certificates, typically pointing to VeriSign's pricing. While the higher validation costs inherent in following the EV Guidelines do engender higher prices relative to other SSL certificate products, a number of CAs have been promoting EV prices below $500[citation needed].

[edit] Evolving understanding of Extended Validation's effect on phishing

In 2006, Stanford University students conducted a usability study[8] of the EV display in Internet Explorer 7. The study attempted to measure users' ability to distinguish real sites from fraudulent sites when presented with various kinds of phishing attacks. Due to the small size of the study's sample base (nine test subjects per cell) the margin for error of each result was several times the actual measurement, and therefore no useful conclusion was possible. However, this study led the way for other researchers to present results of a statistically significant nature. In January 2007, usability research firm Tec-Ed published its results of running 384 North American test subjects through purchasing simulations on sites with and without green address bars. Tec-Ed concluded that latent understanding of green address bars was very high, with 93% of test subjects recognizing a site with a green address bar as a safer shopping experience than one without. With regard to Extended Validation's defense against phishing, the Tec-Ed research reveals that when a site adopts green address bars, then 77% of users visiting what appears to be the same site but without the green address bar will decline to complete the transaction. Apparently, though, these results followed some training, so it is difficult to infer what untrained users would do.[9]

[edit] See also

[edit] Footnotes

  1. ^ The term validation as used here should not be confused with the Certification path validation algorithm commonly found in a certificate context.
  2. ^ A requesting entity is the organization, company, government department or other person that is applying for a certificate.
  3. ^ Guidelines for Extended Validation Certificates
  4. ^ CA/Browser Forum Members
  5. ^ "in IE 7 ... if a website has an Entrust EV SSL Certificate installed, the address bar color will change to green and toggle between the identity of the site and the name of the certificate authority to let the consumer know they can shop with confidence." "EV SSL Certificate FAQ". Entrust. http://www.entrust.net/ssl-technical/ev_faq.htm. Retrieved on 2007-02-05. 
  6. ^ "The colored address bar, a new weapon in the fight against phishing scams, is meant as a sign that a site can be trusted, giving Web surfers the green light to carry out transactions there." "IE 7 gives secure Web sites the green light". CNet. http://news.com.com/IE+7+gives+secure+Web+sites+the+green+light/2100-1029_3-6155826.html. Retrieved on 2007-02-05. 
  7. ^ a b Richmond, Riva (December 19, 2006). "Software to Spot 'Phishers' Irks Small Concerns". Wall Street Journal. http://online.wsj.com/public/article/SB116649577602354120-5U4Afb0JPeyiOy1H_j3fVTUmfG8_20071218.html?mod=rss_free. Retrieved on 2008-06-20. 
  8. ^ Jackson, Collin; Daniel R. Simon, Desney S. Tan, Adam Barth. "An Evaluation of Extended Validation and Picture-in-Picture Phishing Attacks". Usable Security 2007. 
  9. ^ Tec-Ed Inc.. "Extended Validation and VeriSign Brand". http://www.verisign.com/static/040655.pdf. Retrieved on 2008-08-28. 

[edit] References

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