Colleagues.  Just a reminder ... Below is the fourth draft of the WPKOPS 
charter that Jeff Hodges circulated on 19 Oct.  This is the version that we 
will consider in the BoF on Monday.  All the best.  Tim.







The Web PKI is the set of systems and procedures most commonly used, in 
conjunction with security protocols such as TLS, to protect the 
confidentiality, integrity and authenticity of communications between Web 
browsers and Web content servers. More specifically, the Web PKI (as considered 
here) consists of the actual contents of the certificates issued to Web 
application providers by Certification Authorities (CAs), the certificate 
validation services provided by the Authorities to web browsers and their 
users, and the TLS/SSL protocol stacks embedded in web servers and browsers.



The Web PKI first appeared in 1993 or thereabouts and has developed 
continuously in a somewhat organic fashion since then.  Across all the 
suppliers and the point releases of their products, there are now hundreds of 
variations on the Web PKI in regular use.  And this can be a source of problems 
for end-users, certificate holders, and certificate issuers (CAs).



For end-users, there is no clear view whether certificate "problems" remain 
when they see indication of a "good" connection.  For instance, in some 
browsers, a "good" indication may be displayed when a "revoked" response has 
been received and "accepted" by the user, whereas other browsers may refuse to 
display the contents under these circumstances.



Certificate holders may have difficulty understanding whether some browser 
versions will reject their certificate if certain content specifications are 
not met, such as a subject public key that does not satisfy a minimum key size, 
or a certificate policies extension that does not contain a particular standard 
policy identifier.



And for certificate issuers, it can be difficult to predict what proportion of 
the user population will accept a certificate chain with certain 
characteristics.  For instance, when a browser includes a nonce in an OCSP 
request but the server supplies a response that does not include the nonce, it 
is hard to know which browsers will accept and which will reject the response.



Starting from the premise that more consistency in Web security behavior is 
desirable, a natural first step would be to document current and historic 
browser and server behavior.  But, such a project has to be bounded.  
Therefore, only server-authentication behavior encountered in more than 0.1 
percent of connections made by desktop and mobile browsers should be 
considered.  While it is not intended to apply the threshold with any 
precision, it may be used to justify the inclusion or exclusion of a technique.



Future activities may attempt to prescribe how the Web PKI "should" work, and 
the prescription may turn out to be a proper subset of the PKIX PKI.  However, 
that task is explicitly not a goal of the proposed working group.  Instead, the 
group's goal is merely to describe how the Web PKI "actually" works in the set 
of browsers and servers that are in common use today.



Additionally, a number of applications (such as client authentication, document 
signing, code signing, and email) often use the same trust anchors and 
certificate processing mechanisms as used for server authentication on the Web. 
 This reuse creates problems in some situations [1].  While these applications 
are outside the scope of this working group, deliverables should (wherever 
practical within the available expertise and time) identify mechanisms that are 
reused by other applications and identify the implications of that reuse.



Also, the reliability of the Web PKI depends critically on the "practices" of 
its certificate issuers; these practices comprise how certificate issuers 
perform their functions and implement controls, and are described in documents 
known as "Certification Practice Statements" [2][3] and operational 
requirements documents [4][5]. However, the topic of certification practices is 
outside the scope of the working group.



That there are technical shortcomings with Web PKI, as it is practiced today, 
is well recognised.  And, that there is also some urgency in addressing these 
shortcomings is also well recognised.  But, it is felt that too much haste can 
be counter-productive.  The expectation is that the work of this group will 
bring to light, in a systematic way, aspects of the Web PKI that should be 
progressed in future working groups of the IETF's Security Area, and that 
suppliers will be willing to participate in those working groups and modify 
their products to comply with their standards.



Given the urgency of the required developments and the scale of the task, it is 
agreed that adherence to the published schedule should take precedence over 
completeness of the results, though without sacrificing technical correctness.



Milestones

==========



1.    First WG draft of "trust model" document (4 months).

2.    First WG draft of "certificate, CRL, and OCSP field and extension

processing" document (12 months).

3.    First WG draft of "certificate revocation" document (8 months).

4.    First WG draft of "TLS stack operation" document (8 months).

5.    IESG submission of "trust model" document (16 months).

6.    IESG submission of "certificate, CRL, and OCSP field and extension

processing" document (24 months).

7.    IESG submission of "certificate revocation" document (20 months).

8.    IESG submission of "TLS stack operation" document (16 months).





References:



[1] https://www.ietf.org/mail-archive/web/wpkops/current/msg00104.html



[2] Internet X.509 Public Key Infrastructure Certificate Policy and

      Certification Practices Framework. S. Chokhani et al, IETF RFC3647

      https://tools.ietf.org/html/rfc3647



[3] Electronic Signatures and Infrastructures (ESI); Policy requirements for

      certification authorities issuing public key certificates.

      ETSI TS 102 042 V2.2.1 (2011-12)

      http://www.etsi.org/deliver/etsi_ts/102000_102099/102042

      /02.02.01_60/ts_102042v020201p.pdf



[4] Network and certificate system security requirements, CA/Browser Forum,

      Aug 2012, https://www.cabforum.org/Network_Security_Controls_V1.pdf



[5] Baseline Requirements for the Issuance and Management of Publicly-Trusted

      Certificates Version 1.0, CA/Browser Forum, Nov 2011,

      https://www.cabforum.org/Baseline_Requirements_V1.pdf


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