Internet Architecture Board R. Housley
Internet-Draft Vigil Security
Intended status: Informational K. O'Donoghue
Expires: May 4, 2017 Internet Society
October 31, 2016
Improving the Public Key Infrastructure (PKI) for the World Wide Web
draft-iab-web-pki-problems-05
Abstract
The Public Key Infrastructure (PKI) used for the World Wide Web (Web
PKI) is a vital component of trust in the Internet. In recent years,
there have been a number of improvements made to this infrastructure,
including improved certificate status checking, automation, and
transparency of governance. However, additional improvements are
necessary. This document identifies continuing areas of concern and
provides recommendations to the Internet community for additional
improvements, moving toward a more robust and secure Web PKI.
Status of This Memo
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This Internet-Draft will expire on May 4, 2017.
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to this document. Code Components extracted from this document must
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. A Brief Description of the Web PKI . . . . . . . . . . . . . 3
3. Improvements to the Web PKI . . . . . . . . . . . . . . . . . 4
3.1. Strong Cryptography . . . . . . . . . . . . . . . . . . . 4
3.1.1. Preparing for Quantum Computers . . . . . . . . . . . 4
3.1.2. Avoiding Weak Cryptography . . . . . . . . . . . . . 5
3.2. Support for Enterprise PKIs . . . . . . . . . . . . . . . 6
3.3. Web PKI in the Home . . . . . . . . . . . . . . . . . . . 8
3.4. Governance Improvements to the Web PKI . . . . . . . . . 10
4. Security Considerations . . . . . . . . . . . . . . . . . . . 12
5. Privacy Considerations . . . . . . . . . . . . . . . . . . . 12
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Informative References . . . . . . . . . . . . . . . . . . . 13
Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 15
Appendix B. IAB Members at the Time of Approval . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
The Public Key Infrastructure (PKI) for the World Wide Web (Web PKI)
has evolved into a key component of the global Internet; it enables
trusted business and individual transactions. This global
infrastructure has been growing and evolving for many years. The
success of Web PKI has contributed to significant Internet growth.
The Web PKI impacts all aspects of our lives, and no one can imagine
the web without the protections that the Web PKI enables.
As with any maturing technology, there are several problems with the
current Web PKI. The Web PKI makes use of certificates as described
in RFC 5280 [RFC5280]. These certificates are primarily used with
Transport Layer Security (TLS) as described in RFC 5246 [RFC5246].
The economics of the Web PKI value chain are discussed in [VFBH],
[AV], and [AVAV]. This document does not investigate the economic
issues further, but these economic issues provide motivation for
correcting the other problems that are discussed in this document.
One note of caution is that the references above assume the cost of
acquiring a certificate is high. These costs have been decreasing in
recent years due to a number of factors including the Let's Encrypt
initiative discussed later in this document.
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Over the years, many technical improvements have been made to the Web
PKI, but several challenges remain. This document offers a general
set of recommendations to the Internet community designed to be
helpful in addressing these remaining challenges.
2. A Brief Description of the Web PKI
This section provides a very brief introduction to some of the key
concepts of the Web PKI. It is not intended to be a full description
of Web PKI but rather to provide some basic concepts to help frame
the remaining discussion.
Web PKI is an infrastructure comprised of a number of PKIs that
enables the establishment of trust relationships between
communicating web entities. This trust may be chained through
multiple intermediate parties. The root of that trust is referred to
as a trust anchor. A relying party is an entity that depends upon
the trust provided by the infrastructure to make informed decisions.
A complex set of technical, policy, and legal requirements can make
up the qualificiations for a trust anchor in a specific situation.
Certificates are digitally signed structures that contain the
information required to communicate the trust. Certificates are
specified in RFC 5280 [RFC5280]. Certificates contain, among other
things, a subject name, a public key, a limited validity lifetime,
and the digital signature of the Certification Authority (CA).
Certificate users require confidence that the private key associated
with the certified public key is owned by the named subject.
The architectural model used in the Web PKI includes:
EE: End Entity -- the subject of a certificate -- certificates are
issued to end entities including Web servers and clients that
need mutual authentication.
CA: Certification Authority -- the issuer of a certificate --
issues certificates for end entities including Web servers and
clients.
RA: Registration Authority -- an optional system to which a CA
delegates some management functions such as identity validation
or physical credential distribution.
While in its simplest form, the Web PKI is fairly straightforward,
there are a number of concepts that can complicate the relationships
and the behavior. As mentioned already, there can be intermediate
certificates that represent delegation within the certification path.
There can be cross-signing of certificates that creates
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multidimensional relationships. Browsers install numerous trust
anchors associated with many different CAs in the Web PKI. All of
this results in a complex ecosystem of trust relationships that
reflect different operational practices and underlying certificate
policies.
Certificates naturally expire since they contain a validity lifetime.
In some situations, a certificate needs to be revoked before it
expires. Revocation usually happens because the private key is lost
or compromised, but an intermediate CA certificate can be revoked for
bad behavior. All CAs are responsible for providing revocation
status of the certificates that they issue throughout their lifetime
of the certificate. Revocation status information may be provided by
certificate revocation lists (CRLs) [RFC5280], the Online Certificate
Status Protocol (OCSP) [RFC6960], or some other mechanism.
The enrollment process used by a CA makes sure that the subject name
in the certificate is appropriate and that the subject actually holds
the private key. The enrollment process should require the subject
to use the private key; this can be accomplished with PKCS#10
[RFC2986] or some other proof-of-possession mechanism such as
[RFC6955].
3. Improvements to the Web PKI
Over the years, many technical improvements have been made to the Web
PKI. Despite this progress, several challenges remain. This section
discusses several unresolved problems, and it suggests general
directions for tackling them.
3.1. Strong Cryptography
Quantum computers [WIKI-QC] exist today, but they are not yet able to
solve real world problems faster that digital computers. No one
knows whether a large-scale quantum computer will be invented in the
next decade or two that is able to break all of the public key
algorithms that are used in the Web PKI, but it seems prudent to
prepare for such a catastrophic event.
In the mean time, the Web PKI needs to employ cryptographic
algorithms that are secure against known cryptanalytic techniques and
advanced digital computers.
3.1.1. Preparing for Quantum Computers
Hash-based signature algorithms [HASH-S1][HASH-S2] are quantum
resistant, meaning that they are secure even if an attacker is able
to build a large-scale quantum computer. Hash-based signature
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algorithms have small public and private keys, provide fast signing
and verification operation, but they have very large signature values
and one private key can produce a fixed number of signatures. The
number of signatures is set at the time the key pair is generated.
As a result of these properties, hash-based signature algorithms are
not ideal for signing certificates. However, they are well suited
for other uses, including signatures for software updates. The use a
quantum resistant signature algorithm for software updates ensures
that new software can be securely deployed even if a large-scale
quantum computer is invented during the lifetime of the system.
Several signature and key establishment algorithms [WIKI-PQC] are
being investigated that might prove to be quantum resistant and offer
properties that are suitable for use in the Web PKI. So far, none of
these algorithms has achieved wide acceptance. Further research is
needed.
While this research is underway, some security protocols allow a pre-
shared key (PSK) to be mixed with a symmetric key that is established
with a public key algorithms. If the PSK is distributed without the
use of a public key mechanism, the overall key establishment
mechanism will be quantum resistant. Consider the use of a PSK for
information that requires decades of confidentiality protection, such
as health care information.
The Web PKI can prepare for the for quantum computing by:
1. Deploy hash-based signatures for software updates.
2. For information that requires decades of confidentiality
protection, mix a pre-shared key (PSK) as part of the key
establishment.
3. Continue research on quantum resistant public key cryptography.
3.1.2. Avoiding Weak Cryptography
Several digital signature algorithms, one-way hash functions, and
public key sizes that were once considered strong are no longer
considered adequate. This is not a surprise. Cryptographic
algorithms age; they become weaker over time. As new cryptanalysis
techniques are developed and computing capabilities increase, the
amount of time needed to break a particular cryptographic algorithm
will decrease. For this reason, the algorithms and key sizes used in
the Web PKI need to migrate over time.
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CAs and Browser vendors have been managing algorithm and key size
transitions, but it is a significant challenge to maintain a very
high degree of interoperability across the world wide web while
phasing out aged cryptographic algorithms or too small key sizes.
When these appear in a long-lived trust anchor or intermediate CA
certificate, refusal to accept them can impact a very large tree of
certificates. In addition, if a certificate for a web site with a
huge amount of traffic is in that tree, rejecting that certificate
may impact too many users.
Despite this situation, the MD5 and SHA-1 one-way hash functions have
been almost completely eliminated from the Web PKI, and 1024-bit RSA
public keys are essentially gone [MB2015] [MB2016]. It took a very
long time to make this happen, and trust anchors and certificates
that used these cryptographic algorithms were considered valid long
after they were widely known to be too weak.
Obviously, additional algorithm transitions will be needed in the
future. The algorithms and key sizes that are acceptable today will
become weaker with time. RFC 7696 [RFC7696] offers some guidelines
regarding cryptographic algorithm agility.
The Web PKI can prepare for the next transition by:
1. Having experts periodically evaluate the current choices of
algorithm and key size. While it is not possible to predict when
a new cryptanalysis technique will be discovered, the end of the
useful lifetime of most algorithms and key sizes is known many
years in advance.
2. Planning for a smooth and orderly transition from a weak
algorithm or key size. Experience has shown that many years are
needed produce to specifications, develop implementations, and
then deploy replacements.
3. Reducing the lifetime of end-entity certificates to create
frequent opportunities to change an algorithm or key size.
3.2. Support for Enterprise PKIs
Many enterprises operate their own PKI. These enterprises do not
want to be part of the traditional Web PKI, but they face many
challenges in order to achieve a similar user experience and level of
security.
Enterprise PKI users must install one or more enterprise trust
anchors in their operating system or browser. There is readily-
available software that can install trust anchors for use by the
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operating system and browser, but the enterprise PKI will not be
trusted until the system administrator or end user does this step.
Enterprise PKI users often experience greater latency than tradition
Web PKI users. Standards-based and proprietary revocation status
checking approches might offer relief.
The Status Request extension to TLS [RFC6066] allows the web server
to provide status information about its certificate. By including
this extension in the TLS handshake, the browser asks the web server
to provide OCSP responses in addition to the server certificate.
This approach greatly reduces the latency since the browser does not
need to generate an OCSP request or wait for an OCSP response to
check the validity of the server certificate. The inclusion of a
time-stamped OCSP response in the TLS handshake is referred to as
"OCSP stapling". In addition, the MUST_STAPLE feature [TLSFEATURE]
can be used to insist that OCSP stapling be used.
While not widely implemented, the Multiple Certificate Status Request
extension [RFC6961] allows the web server to provide status
information about its own certificate and also the status of
intermediate certificates in the certification path, further reducing
latency.
When OCSP stapling is used by an enterprise, the OCSP responder will
not receive an enormous volume of OCSP requests because the web
servers make a few requests and the responses are passed to the
browsers in the TLS handshake. In addition, OCSP stapling can
improve user privacy, since the web server, not the browser, contacts
the OCSP responder. In this way, the OCSP responder is not able to
determine which browsers are checking the validity of certificate for
particular websites.
Some browser vendors provide a proprietary revocation checking
mechanism that obtains revocation status for the entire Web PKI in a
very compact form. This mechanism eliminates latency since no
network traffic is generated at the time that a certificate is being
validated. However, these mechanisms cover only the trust anchor
store for that browser vendor, excluding all enterprise PKIs. In
addition, measurements in 2015 [IMC2015] show that these mechanisms
do not currently provide adequate coverage of the Web PKI.
Several enterprises issue certificates to all of their employees, and
among other uses, these certificates are used in TLS client
authentication. There is not a common way to import the private key
and the client certificate into browsers. In fact, the private key
can be stored in many different formats depending on the software
used to generate the public/private key pair. PKCS#12 [RFC7292]
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seems to be the most popular format at the moment. A standard way to
import the needed keying material and a standard format will make
this task much easier, and the web might enjoy an increase in mutual
authentication. However, please note the privacy considerations in
Section 5.
Enterprise PKIs can be better supported if:
1. Each enterprise PKI offers an OCSP Responder, and enterprise
websites make use of OCSP Stapling.
2. Operating system and browser vendors support a standard way to
install private keys and certificates for use in client
authentication.
3. In the event that browser vendors continue to offer latency-free
proprietary revocation status checking mechanisms, then these
mechanisms need to expand the coverage to all of the Web PKI and
offer a means to include enterprise PKIs in the coverage.
3.3. Web PKI in the Home
More and more, web protocols are being used to manage devices in the
home. For example, homeowners can use a web browser to connect to a
web site that is embedded in their home router to adjust various
settings. The router allows the browser to access web pages to
adjust these setting as long as the connection originates from the
home network and the proper password is provided. However, there is
no way for the browser to authenticate to the embedded web site.
Authentication of the web site is normally performed during the TLS
handshake, but the Web PKI is not equipped to issue certificates to
home routers or the many other home devices that employ embedded web
sites for homeowner management.
A solution in this environment cannot depend on the homeowner to
perform duties that are normally associated with a web site
administrator. However, some straightforward tasks could be done at
the time the device is installed in the home. These tasks cannot be
more complex than the initial setup of a new printer in the home,
otherwise they will be skipped or done incorrectly.
There are three very different approaches to certificates for home
devices that have been discussed over the years. In the first
approach, a private key and certificate are installed in the device
at the factory. The certificate has an unlimited lifetime. Since it
never expires, no homeowner action is needed to renew it. Also,
since the certificate never changes, the algorithms are selected by
the factory for the lifetime of the device. The subject name in the
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certificate is quite generic, as it must be comprised of information
that is known in the factory. The subject name is often based on
some combination of the manufacturer, model, serial number, and MAC
address. While these do uniquely identify the device, they have
little meaning to the homeowner. A secure device identifier, as
defined in [IEEE802.1AR], is one example of a specification where
locally significant identities can be securely associated with a
manufacturer-provisioned device identifier.
In the second approach, like the first one, a private key and a
certificate that are installed in the device at the factory, but the
homeowner is unaware of them. This factory-installed certificate is
used only to authenticate to a CA operated by the manufacturer. At
the time the device is installed, the homeowner can provide a portion
of the subject name for the device, and the manufacturer CA can issue
a certificate that includes a subject name that the homeowner will
recognize. The certificate can be renewed without any action by the
homeowner at appropriate intervals. Also, following a software
update, the algorithms used in the TLS handshake and the certificate
can be updated.
In the third approach, which is sometimes used today in Internet of
Things devices, the device generates a key pair at the time the
device is configured for the home network, and then a controller on
the local network issues a certificate for the device that contains
the freshly generated public key and a name selected by the user. If
the device is passed on to another user, then a new key pair will be
generated and a new name can be assigned when the device is
configured for that user's network.
Section 3.1.2 of this document calls for the ability to transition
from weak cryptographic algorithms over time. For this reason, and
the ability to use a subject name that the homeowner will recognize,
the second or third approaches are preferred.
One potential problem with the second approach is continuity of
operations of the manufacturer CA. After the device is deployed, the
manufacturer might go out of business or stop offering CA services,
and then come time for renewal of the certificate, there will not be
a CA to issue the new certificate. Some people see this as a way to
end-of-life old equipment, but the users want to choose the end date,
not have one imposed upon them. One possible solution might be
modeled on the domain name business, where other parties will
continue to provide needed services if the original provider stops
doing so.
The Web PKI can prepare for the vast number of home devices that need
certificates by:
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1. Building upon the work being done in the IETF ACME Working Group
[ACMEWG] to facilitate the automatic renewal of certificates for
home devices without any actions by the homeowner beyond the
initial device setup.
2. Establish conventions for the names that appear in certificates
that accomodate the approaches discussed above and also ensure
uniqueness without putting a burden on the homeowner.
3. Working with device manufacturers to establish scalable CAs that
will continue to issue certificates for the deployed devices even
if the manufacturer goes out of business.
4. Working with device manufacturers to establish OCSP Responders so
that the web sites that are embedded in the devices can provide
robust authentication and OCSP stapling in a manner that is
compatible with traditional web sites.
3.4. Governance Improvements to the Web PKI
As with many other technologies, Web PKI technical issues are tangled
up with policy and process issues. Policy and process issues have
evolved over time, sometimes eroding confidence and trust in the Web
PKI. Governance structures are needed that increase transparency and
trust.
Web PKI users are by definition asked to trust CAs. This includes
what CAs are trusted to do properly, and what they are trusted not to
do. The system for determining which CAs are added to or removed
from the trust anchor store in browsers is opaque and confusing to
most Web PKI users. The CA/Browser Forum has developed baseline
requirements for the management and issuance of certificates
[CAB2014] for individual CAs. However, the process by which an
individual CA gets added to the trust anchor store by each of the
browser vendors is somewhat mysterious. The individual browser
vendors determine what should and should not be trusted by including
the CA certificate in their trust anchor store. They do this by
reviewing the CA CPS and reports of audits conducted using the CPA
Canada WebTrust for Certification Authorities criteria [WEBTRUST] or
the ETSI EN 319 411 requirements [ESTI]. The WebTrust for CAs
program also provides a trust mark for CAs meet all the criteria.
Failure to pass an audit can result in the CA being removed from the
trust store.
Once the browser has shipped, regular updates may add or delete CAs.
This is generally not something that a user would monitor. For an
informed user, information about which CAs have been added to or
deleted from the browser trust anchor store can be found in the
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browser release notes. Users can also examine the policies,
practices, and audit reports of the various CAs that have been
developed and posted for the WebTrust Program. How does an
individual, organization, or enterprise really determine if a
particular CA is trustworthy? Do the default choices inherited from
the browser vendors truly represent the organization's trust model?
What constitutes sufficiently bad behavior by a CA to cause removal
from the trust anchor store?
In addition, it can be hazardous for users to remove CAs from the
browser trust anchor store. If a user removes a CA from the browser
trust anchor store, some web sites may become completely inaccessible
or require the user to take explicit action to accept warnings or
bypass browser protections related to untrusted certificates.
CAs can be removed from a trust anchor store as part of the
maintenance of acceptable CAs. There may be a few very large CAs
that are critical to significant portions of the Web PKI. Removing
one of these CAs can have a significant impact on a huge number of
websites. As discussed in briefly in Section 4, users are already
struggling to understand the implications of untrusted certificates,
so they often ignore warnings presented by the browser.
There are a number of organizations that play significant roles in
the operation of the Web PKI, including the CA/Browser Forum, the
WebTrust Task Force, ETSI, and the browser and operating system
vendors. These organizations act on behalf of the entire Internet
community; therefore, transparency in these operations is fundamental
to confidence and trust in the Web PKI. In particular, transparency
in both the CA/Browser Forum and the browser vendor processes would
be helpful. Recently the CA/Browser Forum made some changes to their
operational procedures to make it easier for people to participate
and to improve visibility into their process [CAB1.2]. This is a
significant improvement, but these processes need to continue to
evolve in an open, inclusive, and transparent manner. Currently, as
the name implies, the CA/Browser Forum members primarily represent
CAs and browser vendors. It would be better if relying parties also
have a voice in this forum. Additionally, some browser vendors are
more transparent in their decision processes than others, and it is
felt that all should be more transparent.
Since the Web PKI is widespread, applications beyond the World Wide
Web are making use of the Web PKI. For example, the Web PKI is used
to secure connections between SMTP servers. In these environments,
the browser-centric capabilities are unavailable. The current
governance structure does not provide a way for the relying parties
in these applications to participate.
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The Web PKI governance structures can be made more open and
transparent by:
1. Browser vendors providing additional visibility and tools to
support the management of the trust anchor store.
2. Governance organizations providing a way for all relying parties,
including ones associated with non-browser applications, to
participate.
4. Security Considerations
This document considers some areas for improvement of the Web PKI.
Some of the risks associated with doing nothing or continuing down
the current path are articulated. The Web PKI is a vital component
of a trusted Internet, and as such needs to be improved to sustain
continued growth of the Internet.
Many users find browser error messages related to certificates
confusing. Good man-machine interfaces are always difficult, but in
this situation users are unable to fully understand the risks that
they are accepting, and as a result they do not make informed
decisions about when to proceed and when to stop. This aspect of
browser usability has improved over the years, and there is an
enormous amount of ongoing work on this complex topic. It is hoped
that further improvements will allow users to make better security
choices.
5. Privacy Considerations
Client certificates can be used for mutual authentication. While
mutual authentication is usually consider better than unilateral
authentication, there is a privacy concern in this situation. When
mutual authentication is used, the browser sends the client
certificate in plaintext to the webserver in the TLS handshake. This
allows the browser user's identity to be tracked across many
different sites by anyone that can observe the traffic.
6. IANA Considerations
None.
{{{ RFC Editor: Please remove this section prior to publication. }}}
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7. Informative References
[ACMEWG] IETF, "Charter for Automated Certificate Management
Environment (acme) Working Group", June 2015,
.
[AV] Arnbak, A. and N. van Eijk, "Certificate Authority
Collapse: Regulating Systemic Vulnerabilities in the HTTPS
Value Chain", 2012 TRPC , August 2012,
.
[AVAV] Asghari, H., van Eeten, M., Arnbak, A., and N. van Eijk,
"Security Economics in the HTTPS Value Chain", Workshop on
Economics of Information Security (WEIS) 2013 , 2013,
.
[CAB1.2] CA/Browser Forum, "Bylaws of the CA/Browser Forum",
October 2014, .
[CAB2014] CA/Browser Forum, "CA/Browser Forum Baseline Requirements
for the Issuance and Management of Publicly-Trusted
Certificates, v.1.2.2", October 2014,
.
[IEEE802.1AR]
IEEE Standards Association, "IEEE Standard for Local and
Metropolitan Area Networks -- Secure Device Identity",
2009.
[HASH-S1] McGrew, D. and M. Curcio, "Hash-Based Signatures", draft-
mcgrew-hash-sigs-04 (work in progress), March 2016.
[HASH-S2] Huelsing, A., Butin, D., Gazdag, S., and A. Mohaisen,
"Hash-Based Signatures", draft-irtf-cfrg-xmss-hash-based-
signatures-06 (work in progress), July 2016.
[IMC2015] Liu, Y., Tome, W., Zhang, L., Choffnes, D., Levin, D.,
Maggs, B., Mislove, A., Schulman, A., and C. Wilson, "An
End-to-End Measurement of Certificate Revocation in the
Web's PKI", October 2015,
.
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[MB2015] Wilson, K., "Phase 2: Phasing out Certificates with
1024-bit RSA Keys", January 2015,
.
[MB2016] Barnes, R., "Payment Processors Still Using Weak Crypto",
February 2016,
.
[RFC2986] Nystrom, M. and B. Kaliski, "PKCS #10: Certification
Request Syntax Specification Version 1.7", RFC 2986,
DOI 10.17487/RFC2986, November 2000,
.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008,
.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
.
[RFC6960] Santesson, S., Myers, M., Ankney, R., Malpani, A.,
Galperin, S., and C. Adams, "X.509 Internet Public Key
Infrastructure Online Certificate Status Protocol - OCSP",
RFC 6960, DOI 10.17487/RFC6960, June 2013,
.
[RFC6961] Pettersen, Y., "The Transport Layer Security (TLS)
Multiple Certificate Status Request Extension", RFC 6961,
DOI 10.17487/RFC6961, June 2013,
.
[RFC6066] Eastlake 3rd, D., "Transport Layer Security (TLS)
Extensions: Extension Definitions", RFC 6066,
DOI 10.17487/RFC6066, January 2011,
.
[RFC6955] Schaad, J. and H. Prafullchandra, "Diffie-Hellman Proof-
of-Possession Algorithms", RFC 6955, DOI 10.17487/RFC6955,
May 2013, .
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[RFC7292] Moriarty, K., Ed., Nystrom, M., Parkinson, S., Rusch, A.,
and M. Scott, "PKCS #12: Personal Information Exchange
Syntax v1.1", RFC 7292, DOI 10.17487/RFC7292, July 2014,
.
[RFC7696] Housley, R., "Guidelines for Cryptographic Algorithm
Agility and Selecting Mandatory-to-Implement Algorithms",
BCP 201, RFC 7696, DOI 10.17487/RFC7696, November 2015,
.
[TLSFEATURE]
Hallam-Baker, P., "X.509v3 TLS Feature Extension", draft-
hallambaker-tlsfeature-10 (work in progress), July 2015.
[VFBH] Vratonjic, N., Freudiger, J., Bindschaedler, V., and J.
Hubaux, "The Inconvenient Truth About Web Certificates",
Workshop on Economics of Information Security (WEIS)
2011 , 2011,
.
[WEBTRUST]
CPA Canada, "WebTrust Program for Certification
Authorities", August 2015, .
[WIKI-PQC]
Wikipedia, "Post-quantum cryptography", October 2016,
.
[WIKI-QC] Wikipedia, "Quantum computing", October 2016,
.
Appendix A. Acknowledgements
This document has been developed within the IAB Privacy and Security
Program. The authors greatly appreciate the review and suggestions
provided by Rick Andrews, Mary Barnes, Richard Barnes, Marc Blanchet,
Peter Bowen, Alissa Cooper, Nick Doty, Stephen Farrell, Joe Hall, Ted
Hardie, Paul Hoffman, Ralph Holz, Lee Howard, Christian Huitema,
Eliot Lear, Xing Li, Lucy Lynch, Gervase Markham, Eric Rescorla,
Andrei Robachevsky, Thomas Roessler, Jeremy Rowley, Christine
Runnegar, Jakob Schlyter, Wendy Seltzer, Dave Thaler, Brian Trammell,
and Juan Carlos Zuniga.
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Appendix B. IAB Members at the Time of Approval
{{{ RFC Editor: Please add the names to the IAB members at the time
that this document is put into the RFC Editor queue. }}}
Authors' Addresses
Russ Housley
Vigil Security
918 Spring Knoll Drive
Herndon, VA 20170
USA
Email: housley@vigilsec.com
Karen O'Donoghue
Internet Society
1775 Wiehle Ave #201
Reston, VA 20190
USA
Email: odonoghue@isoc.org
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