rfc8879xml2.original.xml   rfc8879.xml 
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<rfc docName="draft-ietf-tls-certificate-compression-10" category="std"> <rfc xmlns:xi="http://www.w3.org/2001/XInclude" ipr="trust200902"
docName="draft-ietf-tls-certificate-compression-10" number="8879"
obsoletes="" updates="" submissionType="IETF" category="std"
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<front> <front>
<title abbrev="TLS Certificate Compression">TLS Certificate Compression</tit le> <title abbrev="TLS Certificate Compression">TLS Certificate Compression</tit le>
<seriesInfo name="RFC" value="8879"/>
<author initials="A." surname="Ghedini" fullname="Alessandro Ghedini"> <author initials="A." surname="Ghedini" fullname="Alessandro Ghedini">
<organization>Cloudflare, Inc.</organization> <organization>Cloudflare, Inc.</organization>
<address> <address>
<email>alessandro@cloudflare.com</email> <email>alessandro@cloudflare.com</email>
</address> </address>
</author> </author>
<author initials="V." surname="Vasiliev" fullname="Victor Vasiliev"> <author initials="V." surname="Vasiliev" fullname="Victor Vasiliev">
<organization>Google</organization> <organization>Google</organization>
<address> <address>
<email>vasilvv@google.com</email> <email>vasilvv@google.com</email>
</address> </address>
</author> </author>
<date year="2020" month="August"/>
<date year="2020" month="January" day="06"/>
<area>Security</area> <area>Security</area>
<workgroup>TLS</workgroup> <workgroup>TLS</workgroup>
<abstract> <abstract>
<t>In TLS handshakes, certificate chains often take up
<t>In TLS handshakes, certificate chains often take up
the majority of the bytes transmitted.</t> the majority of the bytes transmitted.</t>
<t>This document describes how certificate chains can be compressed to red
<t>This document describes how certificate chains can be compressed to reduce th uce the
e
amount of data transmitted and avoid some round trips.</t> amount of data transmitted and avoid some round trips.</t>
</abstract> </abstract>
</front> </front>
<middle> <middle>
<section anchor="introduction" numbered="true" toc="default">
<section anchor="introduction" title="Introduction"> <name>Introduction</name>
<t>In order to reduce latency and improve performance, it can be useful to
<t>In order to reduce latency and improve performance it can be useful to reduce reduce
the amount of data exchanged during a TLS handshake.</t> the amount of data exchanged during a TLS handshake.</t>
<t><xref target="RFC7924" format="default"/> describes a mechanism that al
<t><xref target="RFC7924"></xref> describes a mechanism that allows a client and lows a client and a server to avoid
a server to avoid
transmitting certificates already shared in an earlier handshake, but it transmitting certificates already shared in an earlier handshake, but it
doesn’t help when the client connects to a server for the first time and doesn't help when the client connects to a server for the first time and
doesn’t already have knowledge of the server’s certificate chain.</t> doesn't already have knowledge of the server's certificate chain.</t>
<t>This document describes a mechanism that would allow certificates to be
<t>This document describes a mechanism that would allow certificates to be
compressed during all handshakes.</t> compressed during all handshakes.</t>
</section>
<section anchor="notational-conventions" numbered="true" toc="default">
<name>Notational Conventions</name>
<t>
The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQU
IRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>
RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
"<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to
be interpreted as
described in BCP&nbsp;14 <xref target="RFC2119"/> <xref target="RFC8174"/>
when, and only when, they appear in all capitals, as shown here.
</t>
</section> </section>
<section anchor="notational-conventions" title="Notational Conventions"> <section anchor="negotiating-certificate-compression" numbered="true" toc="d
efault">
<t>The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, <name>Negotiating Certificate Compression</name>
“SHOULD NOT”, “RECOMMENDED”, “NOT RECOMMENDED”, “MAY”, and “OPTIONAL” in this <t>This extension is only supported with TLS 1.3 <xref target="RFC8446" fo
document are to be interpreted as described in BCP 14 <xref target="RFC2119"/> < rmat="default"/> and newer; if TLS 1.2
xref target="RFC8174"/> <xref target="RFC5246" format="default"/> or earlier is negotiated, the peers <b
when, and only when, they appear in all capitals, as shown here.</t> cp14>MUST</bcp14> ignore this extension.</t>
<t>This document defines a new extension type (compress_certificate(27)),
</section> which
<section anchor="negotiating-certificate-compression" title="Negotiating Certifi
cate Compression">
<t>This extension is only supported with TLS 1.3 <xref target="RFC8446"></xref>
and newer; if TLS 1.2
<xref target="RFC5246"></xref> or earlier is negotiated, the peers MUST ignore t
his extension.</t>
<t>This document defines a new extension type (compress_certificate(27)), which
can be used to signal the supported compression formats for the Certificate can be used to signal the supported compression formats for the Certificate
message to the peer. Whenever it is sent by the client as a ClientHello message message to the peer. Whenever it is sent by the client as a ClientHello message
extension (<xref target="RFC8446"></xref>, Section 4.1.2), it indicates the supp ort for extension (<xref target="RFC8446" sectionFormat="comma" section="4.1.2"/>), it i ndicates support for
compressed server certificates. Whenever it is sent by the server as a compressed server certificates. Whenever it is sent by the server as a
CertificateRequest extension (<xref target="RFC8446"></xref>, Section 4.3.2), it CertificateRequest extension (<xref target="RFC8446" sectionFormat="comma"
indicates section="4.3.2"/>), it indicates support for compressed client certificates.</t>
the support for compressed client certificates.</t> <t>By sending a compress_certificate extension, the sender indicates to th
e peer
<t>By sending a compress_certificate extension, the sender indicates to the peer the certificate-compression algorithms it is willing to use for decompression.
the certificate compression algorithms it is willing to use for decompression. The "extension_data" field of this extension <bcp14>SHALL</bcp14> contain a
The “extension_data” field of this extension SHALL contain a CertificateCompressionAlgorithms value:</t>
CertificateCompressionAlgorithms value:</t>
<figure><artwork><![CDATA[ <sourcecode type="tls-presentation">
enum { enum {
zlib(1), zlib(1),
brotli(2), brotli(2),
zstd(3), zstd(3),
(65535) (65535)
} CertificateCompressionAlgorithm; } CertificateCompressionAlgorithm;
struct { struct {
CertificateCompressionAlgorithm algorithms<2..2^8-2&gt;; CertificateCompressionAlgorithm algorithms<2..2^8-2&gt;;
} CertificateCompressionAlgorithms; } CertificateCompressionAlgorithms;
]]></artwork></figure> </sourcecode>
<t>The compress_certificate extension is a unidirectional indication; no <t>The compress_certificate extension is a unidirectional indication; no
corresponding response extension is needed.</t> corresponding response extension is needed.</t>
</section>
</section> <section anchor="compressed-certificate-message" numbered="true" toc="defaul
<section anchor="compressed-certificate-message" title="Compressed Certificate M t">
essage"> <name>Compressed Certificate Message</name>
<t>If the peer has indicated that it supports compression, server and
<t>If the peer has indicated that it supports compression, server and client MAY client <bcp14>MAY</bcp14>
compress their corresponding Certificate messages (Section 4.4.2 of <xref target compress their corresponding Certificate messages (<xref
="RFC8446"/>) target="RFC8446" sectionFormat="of" section="4.4.2"/>)
and send them in the form of the CompressedCertificate message (replacing the and send them in the form of the CompressedCertificate message (replacing the
Certificate message).</t> Certificate message).</t>
<t>The CompressedCertificate message is formed as follows:</t>
<t>The CompressedCertificate message is formed as follows:</t> <sourcecode>
<figure><artwork><![CDATA[
struct { struct {
CertificateCompressionAlgorithm algorithm; CertificateCompressionAlgorithm algorithm;
uint24 uncompressed_length; uint24 uncompressed_length;
opaque compressed_certificate_message<1..2^24-1&gt;; opaque compressed_certificate_message<1..2^24-1&gt;;
} CompressedCertificate; } CompressedCertificate;
]]></artwork></figure> </sourcecode>
<dl newline="false" spacing="normal">
<t><list style="hanging"> <dt>algorithm:</dt>
<t hangText='algorithm'> <dd>The algorithm used to compress the certificate. The algorithm
The algorithm used to compress the certificate. The algorithm MUST be one of <bcp14>MUST</bcp14> be one of
the algorithms listed in the peer’s compress_certificate extension.</t> the algorithms listed in the peer's compress_certificate extension.</dd>
<t hangText='uncompressed_length'> <dt>uncompressed_length:</dt>
The length of the Certificate message once it is uncompressed. If after <dd>
decompression the specified length does not match the actual length, the The length of the Certificate message once it is uncompressed. If, after
party receiving the invalid message MUST abort the connection with the decompression, the specified length does not match the actual length, the
“bad_certificate” alert. The presence of this field allows the receiver to party receiving the invalid message <bcp14>MUST</bcp14> abort the connection wit
pre-allocate the buffer for the uncompressed Certificate message and to h the
enforce limits on the message size before performing decompression.</t> "bad_certificate" alert. The presence of this field allows the receiver to
<t hangText='compressed_certificate_message'> preallocate the buffer for the uncompressed Certificate message and enforce
limits on the message size before performing decompression.</dd>
<dt>compressed_certificate_message:</dt>
<dd>
The result of applying the indicated compression algorithm to the encoded The result of applying the indicated compression algorithm to the encoded
Certificate message that would have been sent if certificate compression was not Certificate message that would have been sent if certificate compression was not
in use. The compression algorithm defines how the in use. The compression algorithm defines how the
bytes in the compressed_certificate_message field are converted into the bytes in the compressed_certificate_message field are converted into the
Certificate message.</t> Certificate message.</dd>
</list></t> </dl>
<t>If the specified compression algorithm is zlib, then the Certificate me
<t>If the specified compression algorithm is zlib, then the Certificate message ssage
MUST be compressed with the ZLIB compression algorithm, as defined in <xref targ <bcp14>MUST</bcp14> be compressed with the ZLIB compression algorithm, as define
et="RFC1950"></xref>. d in <xref target="RFC1950" format="default"/>.
If the specified compression algorithm is brotli, the Certificate message MUST If the specified compression algorithm is brotli, the Certificate message <bcp14
be compressed with the Brotli compression algorithm as defined in <xref target=" >MUST</bcp14>
RFC7932"></xref>. If be compressed with the Brotli compression algorithm, as defined in <xref target=
the specified compression algorithm is zstd, the Certificate message MUST be "RFC7932" format="default"/>. If
compressed with the Zstandard compression algorithm as defined in <xref target=" the specified compression algorithm is zstd, the Certificate message <bcp14>MUST
I-D.kucherawy-rfc8478bis"></xref>.</t> </bcp14> be
compressed with the Zstandard compression algorithm, as defined in <xref target=
<t>It is possible to define a certificate compression algorithm that uses a "RFC8878" format="default"/>.</t>
pre-shared dictionary to achieve higher compression ratio. This document does <t>It is possible to define a certificate compression algorithm that uses
a
preshared dictionary to achieve a higher compression ratio. This document does
not define any such algorithms, but additional codepoints may be allocated for not define any such algorithms, but additional codepoints may be allocated for
such use per the policy in <xref target="registry"/>.</t> such use per the policy in <xref target="registry" format="default"/>.</t>
<t>If the received CompressedCertificate message cannot be decompressed, t
<t>If the received CompressedCertificate message cannot be decompressed, the he
connection MUST be terminated with the “bad_certificate” alert.</t> connection <bcp14>MUST</bcp14> be terminated with the "bad_certificate" alert.</
t>
<t>If the format of the Certificate message is altered using the <t>If the format of the Certificate message is altered using the
server_certificate_type or client_certificate_type extensions <xref target="RFC7 server_certificate_type or client_certificate_type extensions <xref target="RFC7
250"></xref>, the 250" format="default"/>, the
resulting altered message is compressed instead.</t> resulting altered message is compressed instead.</t>
</section>
</section> <section anchor="security-considerations" numbered="true" toc="default">
<section anchor="security-considerations" title="Security Considerations"> <name>Security Considerations</name>
<t>After decompression, the Certificate message <bcp14>MUST</bcp14> be pro
<t>After decompression, the Certificate message MUST be processed as if it were cessed as if it were
encoded without being compressed. This way, the parsing and the verification encoded without being compressed. This way, the parsing and the verification
have the same security properties as they would have in TLS normally.</t> have the same security properties as they would have in TLS normally.</t>
<t>In order for certificate compression to function correctly, the underly
<t>In order for certificate compression to function correctly, the underlying ing
compression algorithm MUST output the same data compression algorithm <bcp14>MUST</bcp14> output the same data
that was provided as input by the peer.</t> that was provided as input by the peer.</t>
<t>Since certificate chains are typically presented on a per-server-name o
<t>Since certificate chains are typically presented on a per-server name or r
per-user basis, a malicious application does not have control over any individua l fragments per-user basis, a malicious application does not have control over any individua l fragments
in the Certificate message, meaning that they cannot leak information about the in the Certificate message, meaning that they cannot leak information about the
certificate by modifying the plaintext.</t> certificate by modifying the plaintext.</t>
<t>Implementations <bcp14>SHOULD</bcp14> bound the memory usage when decom
<t>Implementations SHOULD bound the memory usage when decompressing the pressing the
CompressedCertificate message.</t> CompressedCertificate message.</t>
<t>Implementations <bcp14>MUST</bcp14> limit the size of the resulting dec
<t>Implementations MUST limit the size of the resulting decompressed chain to ompressed chain to
the specified uncompressed length, and they MUST abort the connection if the the specified uncompressed length, and they <bcp14>MUST</bcp14> abort the connec
tion if the
size of the output of the decompression function exceeds that limit. TLS framin g size of the output of the decompression function exceeds that limit. TLS framin g
imposes 16777216 byte limit on the certificate message size, and the implementat imposes a 16777216-byte limit on the certificate message size, and implementatio
ions ns
MAY impose a limit that is lower than that; in both cases, they MUST apply the s <bcp14>MAY</bcp14> impose a limit that is lower than that; in both cases, they <
ame bcp14>MUST</bcp14> apply the same
limit as if no compression were used.</t> limit as if no compression were used.</t>
<t>While the Certificate message in TLS 1.3 is encrypted, third parties ca
<t>While the Certificate message in TLS 1.3 is encrypted, third parties can draw n draw
inferences from the message length observed on the wire. TLS 1.3 provides a pad ding inferences from the message length observed on the wire. TLS 1.3 provides a pad ding
mechanism (discussed in Sections 5.4 and E.3 of <xref target="RFC8446"></xref>) mechanism (discussed in Sections <xref target="RFC8446"
to counteract such sectionFormat="bare" section="5.4"/> and <xref target="RFC8446"
sectionFormat="bare" section="E.3"/> of <xref target="RFC8446"/>) to counteract
such
analysis. Certificate compression alters the length of the Certificate message, analysis. Certificate compression alters the length of the Certificate message,
and the change in length is dependent on the actual contents of the certificate. and the change in length is dependent on the actual contents of the certificate.
Any padding scheme covering the Certificate message has to address compression Any padding scheme covering the Certificate message has to address compression
within its design, or disable it altogether.</t> within its design or disable it altogether.</t>
</section>
</section> <section anchor="middlebox-compatibility" numbered="true" toc="default">
<section anchor="middlebox-compatibility" title="Middlebox Compatibility"> <name>Middlebox Compatibility</name>
<t>It's been observed that a significant number of middleboxes intercept a
<t>It’s been observed that a significant number of middleboxes intercept and try nd try
to validate the Certificate message exchanged during a TLS handshake. This to validate the Certificate message exchanged during a TLS handshake. This
means that middleboxes that don’t understand the CompressedCertificate message means that middleboxes that don't understand the CompressedCertificate message
might misbehave and drop connections that adopt certificate compression. might misbehave and drop connections that adopt certificate compression.
Because of that, the extension is only supported in the versions of TLS where Because of that, the extension is only supported in the versions of TLS where
the certificate message is encrypted in a way that prevents middleboxes from the certificate message is encrypted in a way that prevents middleboxes from
intercepting it, that is, TLS version 1.3 <xref target="RFC8446"></xref> and hig intercepting it -- that is, TLS version 1.3 <xref target="RFC8446" format="defau
her.</t> lt"/> and higher.</t>
</section>
</section> <section anchor="iana-considerations" numbered="true" toc="default">
<section anchor="iana-considerations" title="IANA Considerations"> <name>IANA Considerations</name>
<section anchor="update-of-the-tls-extensiontype-registry" numbered="true"
<section anchor="update-of-the-tls-extensiontype-registry" title="Update of the toc="default">
TLS ExtensionType Registry"> <name>TLS ExtensionType Values</name>
<t>IANA has created an entry, compress_certificate(27), in the
<t>Create an entry, compress_certificate(27), in the existing registry for "TLS ExtensionType Values" registry (defined in <xref
ExtensionType (defined in <xref target="RFC8446"></xref>), with “TLS 1.3” column target="RFC8446" format="default"/>) with the values in the "TLS 1.3" col
values umn
being set to “CH, CR”, and “Recommended” column being set to “Yes”.</t> set to "CH, CR" and the "Recommended" column entry set to "Yes".</t>
</section>
</section> <section anchor="update-of-the-tls-handshaketype-registry" numbered="true"
<section anchor="update-of-the-tls-handshaketype-registry" title="Update of the toc="default">
TLS HandshakeType Registry"> <name>TLS HandshakeType</name>
<t>IANA has created an entry, compressed_certificate(25), in
<t>Create an entry, compressed_certificate(25), in the existing registry for the "TLS Handshake Type" registry (defined in <xref
HandshakeType (defined in <xref target="RFC8446"></xref>), with “DTLS-OK” column target="RFC8446" format="default"/>), with the "DTLS-OK" column value set
value being set to to
“Yes”.</t> "Yes".</t>
</section>
</section> <section anchor="registry" numbered="true" toc="default">
<section anchor="registry" title="Registry for Compression Algorithms"> <name>Compression Algorithms</name>
<t>This document establishes a registry of compression algorithms suppor
<t>This document establishes a registry of compression algorithms supported for ted for
compressing the Certificate message, titled “Certificate Compression Algorithm compressing the Certificate message, titled "TLS Certificate Compression Algorit
IDs”, under the existing “Transport Layer Security (TLS) Extensions” heading.</t hm
> IDs", under the existing "Transport Layer Security (TLS) Extensions" registry.</
t>
<t>The entries in the registry are:</t> <t>The entries in the registry are:</t>
<table align="center">
<texttable> <name>TLS Certificate Compression Algorithm IDs</name>
<ttcol align='left'>Algorithm Number</ttcol> <thead>
<ttcol align='left'>Description</ttcol> <tr>
<ttcol align='left'>Reference</ttcol> <th align="left">Algorithm Number</th>
<c>0</c> <th align="left">Description</th>
<c>Reserved</c> <th align="left">Reference</th>
<c>&#160;</c> </tr>
<c>1</c> </thead>
<c>zlib</c>
<c>[this document]</c>
<c>2</c>
<c>brotli</c>
<c>[this document]</c>
<c>3</c>
<c>zstd</c>
<c>[this document]</c>
<c>16384 to 65535</c>
<c>Reserved for Experimental Use</c>
<c>&#160;</c>
</texttable>
<t>The values in this registry shall be allocated under “IETF Review” policy for <tbody>
values strictly smaller than 256, under “Specification Required” policy for <tr>
values 256-16383, and under “Experimental Use” otherwise (see <xref target="RFC8 <td align="left">0</td>
126"></xref> for the <td align="left">Reserved</td>
<td align="left">RFC 8879</td>
</tr>
<tr>
<td align="left">1</td>
<td align="left">zlib</td>
<td align="left">RFC 8879</td>
</tr>
<tr>
<td align="left">2</td>
<td align="left">brotli</td>
<td align="left">RFC 8879</td>
</tr>
<tr>
<td align="left">3</td>
<td align="left">zstd</td>
<td align="left">RFC 8879</td>
</tr>
<tr>
<td align="left">16384 to 65535</td>
<td align="left">Reserved for Experimental Use</td>
<td align="left">&nbsp;</td>
</tr>
</tbody>
</table>
<t>The values in this registry shall be allocated under "IETF Review" po
licy for
values strictly smaller than 256, under "Specification Required" policy for
values 256-16383, and under "Experimental Use" otherwise (see <xref target="RFC8
126" format="default"/> for the
definition of relevant policies). Experimental Use extensions can be used both definition of relevant policies). Experimental Use extensions can be used both
on private networks and over the open Internet.</t> on private networks and over the open Internet.</t>
<t>The procedures for requesting values in the Specification Required sp
<t>The procedures for requesting values in the Specification Required space are ace are
specified in Section 17 of <xref target="RFC8447"></xref>.</t> specified in <xref target="RFC8447" sectionFormat="of" section="17"/>.</t>
</section>
</section> </section>
</section>
</middle> </middle>
<back> <back>
<references>
<name>References</name>
<references>
<name>Normative References</name>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.1950.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.2119.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.7250.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.7932.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.7924.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8126.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8174.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8446.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.8447.xml"/>
<references title='Normative References'> <!-- [rfced] [I-D.kucherawy-rfc8478bis]; companion document RFC 8878 -->
<reference anchor="RFC1950" target='https://www.rfc-editor.org/info/rfc1950'>
<front>
<title>ZLIB Compressed Data Format Specification version 3.3</title>
<author initials='P.' surname='Deutsch' fullname='P. Deutsch'><organization /></
author>
<author initials='J-L.' surname='Gailly' fullname='J-L. Gailly'><organization />
</author>
<date year='1996' month='May' />
<abstract><t>This specification defines a lossless compressed data format. This
memo provides information for the Internet community. This memo does not speci
fy an Internet standard of any kind.</t></abstract>
</front>
<seriesInfo name='RFC' value='1950'/>
<seriesInfo name='DOI' value='10.17487/RFC1950'/>
</reference>
<reference anchor="RFC2119" target='https://www.rfc-editor.org/info/rfc2119'>
<front>
<title>Key words for use in RFCs to Indicate Requirement Levels</title>
<author initials='S.' surname='Bradner' fullname='S. Bradner'><organization /></
author>
<date year='1997' month='March' />
<abstract><t>In many standards track documents several words are used to signify
the requirements in the specification. These words are often capitalized. This
document defines these words as they should be interpreted in IETF documents.
This document specifies an Internet Best Current Practices for the Internet Comm
unity, and requests discussion and suggestions for improvements.</t></abstract>
</front>
<seriesInfo name='BCP' value='14'/>
<seriesInfo name='RFC' value='2119'/>
<seriesInfo name='DOI' value='10.17487/RFC2119'/>
</reference>
<reference anchor="RFC7250" target='https://www.rfc-editor.org/info/rfc7250'>
<front>
<title>Using Raw Public Keys in Transport Layer Security (TLS) and Datagram Tran
sport Layer Security (DTLS)</title>
<author initials='P.' surname='Wouters' fullname='P. Wouters' role='editor'><org
anization /></author>
<author initials='H.' surname='Tschofenig' fullname='H. Tschofenig' role='editor
'><organization /></author>
<author initials='J.' surname='Gilmore' fullname='J. Gilmore'><organization /></
author>
<author initials='S.' surname='Weiler' fullname='S. Weiler'><organization /></au
thor>
<author initials='T.' surname='Kivinen' fullname='T. Kivinen'><organization /></
author>
<date year='2014' month='June' />
<abstract><t>This document specifies a new certificate type and two TLS extensio
ns for exchanging raw public keys in Transport Layer Security (TLS) and Datagram
Transport Layer Security (DTLS). The new certificate type allows raw public ke
ys to be used for authentication.</t></abstract>
</front>
<seriesInfo name='RFC' value='7250'/>
<seriesInfo name='DOI' value='10.17487/RFC7250'/>
</reference>
<reference anchor="RFC7932" target='https://www.rfc-editor.org/info/rfc7932'>
<front>
<title>Brotli Compressed Data Format</title>
<author initials='J.' surname='Alakuijala' fullname='J. Alakuijala'><organizatio
n /></author>
<author initials='Z.' surname='Szabadka' fullname='Z. Szabadka'><organization />
</author>
<date year='2016' month='July' />
<abstract><t>This specification defines a lossless compressed data format that c
ompresses data using a combination of the LZ77 algorithm and Huffman coding, wit
h efficiency comparable to the best currently available general-purpose compress
ion methods.</t></abstract>
</front>
<seriesInfo name='RFC' value='7932'/>
<seriesInfo name='DOI' value='10.17487/RFC7932'/>
</reference>
<reference anchor="RFC7924" target='https://www.rfc-editor.org/info/rfc7924'>
<front>
<title>Transport Layer Security (TLS) Cached Information Extension</title>
<author initials='S.' surname='Santesson' fullname='S. Santesson'><organization
/></author>
<author initials='H.' surname='Tschofenig' fullname='H. Tschofenig'><organizatio
n /></author>
<date year='2016' month='July' />
<abstract><t>Transport Layer Security (TLS) handshakes often include fairly stat
ic information, such as the server certificate and a list of trusted certificati
on authorities (CAs). This information can be of considerable size, particularl
y if the server certificate is bundled with a complete certificate chain (i.e.,
the certificates of intermediate CAs up to the root CA).</t><t>This document def
ines an extension that allows a TLS client to inform a server of cached informat
ion, thereby enabling the server to omit already available information.</t></abs
tract>
</front>
<seriesInfo name='RFC' value='7924'/>
<seriesInfo name='DOI' value='10.17487/RFC7924'/>
</reference>
<reference anchor="RFC8126" target='https://www.rfc-editor.org/info/rfc8126'>
<front>
<title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
<author initials='M.' surname='Cotton' fullname='M. Cotton'><organization /></au
thor>
<author initials='B.' surname='Leiba' fullname='B. Leiba'><organization /></auth
or>
<author initials='T.' surname='Narten' fullname='T. Narten'><organization /></au
thor>
<date year='2017' month='June' />
<abstract><t>Many protocols make use of points of extensibility that use constan
ts to identify various protocol parameters. To ensure that the values in these
fields do not have conflicting uses and to promote interoperability, their alloc
ations are often coordinated by a central record keeper. For IETF protocols, th
at role is filled by the Internet Assigned Numbers Authority (IANA).</t><t>To ma
ke assignments in a given registry prudently, guidance describing the conditions
under which new values should be assigned, as well as when and how modification
s to existing values can be made, is needed. This document defines a framework
for the documentation of these guidelines by specification authors, in order to
assure that the provided guidance for the IANA Considerations is clear and addre
sses the various issues that are likely in the operation of a registry.</t><t>Th
is is the third edition of this document; it obsoletes RFC 5226.</t></abstract>
</front>
<seriesInfo name='BCP' value='26'/>
<seriesInfo name='RFC' value='8126'/>
<seriesInfo name='DOI' value='10.17487/RFC8126'/>
</reference>
<reference anchor="RFC8174" target='https://www.rfc-editor.org/info/rfc8174'>
<front>
<title>Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</title>
<author initials='B.' surname='Leiba' fullname='B. Leiba'><organization /></auth
or>
<date year='2017' month='May' />
<abstract><t>RFC 2119 specifies common key words that may be used in protocol s
pecifications. This document aims to reduce the ambiguity by clarifying that on
ly UPPERCASE usage of the key words have the defined special meanings.</t></abs
tract>
</front>
<seriesInfo name='BCP' value='14'/>
<seriesInfo name='RFC' value='8174'/>
<seriesInfo name='DOI' value='10.17487/RFC8174'/>
</reference>
<reference anchor="RFC8446" target='https://www.rfc-editor.org/info/rfc8446'>
<front>
<title>The Transport Layer Security (TLS) Protocol Version 1.3</title>
<author initials='E.' surname='Rescorla' fullname='E. Rescorla'><organization />
</author>
<date year='2018' month='August' />
<abstract><t>This document specifies version 1.3 of the Transport Layer Security
(TLS) protocol. TLS allows client/server applications to communicate over the
Internet in a way that is designed to prevent eavesdropping, tampering, and mess
age forgery.</t><t>This document updates RFCs 5705 and 6066, and obsoletes RFCs
5077, 5246, and 6961. This document also specifies new requirements for TLS 1.2
implementations.</t></abstract>
</front>
<seriesInfo name='RFC' value='8446'/>
<seriesInfo name='DOI' value='10.17487/RFC8446'/>
</reference>
<reference anchor="RFC8447" target='https://www.rfc-editor.org/info/rfc8447'>
<front>
<title>IANA Registry Updates for TLS and DTLS</title>
<author initials='J.' surname='Salowey' fullname='J. Salowey'><organization /></
author>
<author initials='S.' surname='Turner' fullname='S. Turner'><organization /></au
thor>
<date year='2018' month='August' />
<abstract><t>This document describes a number of changes to TLS and DTLS IANA re
gistries that range from adding notes to the registry all the way to changing th
e registration policy. These changes were mostly motivated by WG review of the
TLS- and DTLS-related registries undertaken as part of the TLS 1.3 development p
rocess.</t><t>This document updates the following RFCs: 3749, 5077, 4680, 5246,
5705, 5878, 6520, and 7301.</t></abstract>
</front>
<seriesInfo name='RFC' value='8447'/>
<seriesInfo name='DOI' value='10.17487/RFC8447'/>
</reference>
<reference anchor="I-D.kucherawy-rfc8478bis"> <reference anchor='RFC8878'>
<front> <front>
<title>Zstandard Compression and the application/zstd Media Type</title> <title>Zstandard Compression and the 'application/zstd' Media Type</title>
<author initials='Y' surname='Collet' fullname='Yann Collet'> <author initials='Y' surname='Collet' fullname='Yann Collet'>
<organization /> <organization />
</author> </author>
<author initials='M' surname='Kucherawy' fullname='Murray Kucherawy'> <author initials='M' surname='Kucherawy' fullname='Murray Kucherawy' role="edito r">
<organization /> <organization />
</author> </author>
<date month='December' day='20' year='2019' /> <date month='August' year='2020' />
<abstract><t>Zstandard, or "zstd" (pronounced "zee standard"), is a data compres
sion mechanism. This document describes the mechanism and registers a media typ
e and content encoding to be used when transporting zstd-compressed content via
Multipurpose Internet Mail Extensions (MIME). Despite use of the word "standard
" as part of its name, readers are advised that this document is not an Internet
Standards Track specification; it is being published for informational purposes
only. This document replaces and obsoletes RFC 8478.</t></abstract>
</front>
<seriesInfo name='Internet-Draft' value='draft-kucherawy-rfc8478bis-03' />
<format type='TXT'
target='http://www.ietf.org/internet-drafts/draft-kucherawy-rfc8478bis-0
3.txt' />
</reference>
</references>
<references title='Informative References'>
<reference anchor="RFC5246" target='https://www.rfc-editor.org/info/rfc5246'>
<front>
<title>The Transport Layer Security (TLS) Protocol Version 1.2</title>
<author initials='T.' surname='Dierks' fullname='T. Dierks'><organization /></au
thor>
<author initials='E.' surname='Rescorla' fullname='E. Rescorla'><organization />
</author>
<date year='2008' month='August' />
<abstract><t>This document specifies Version 1.2 of the Transport Layer Security
(TLS) protocol. The TLS protocol provides communications security over the Int
ernet. The protocol allows client/server applications to communicate in a way t
hat is designed to prevent eavesdropping, tampering, or message forgery. [STAND
ARDS-TRACK]</t></abstract>
</front> </front>
<seriesInfo name='RFC' value='5246'/> <seriesInfo name="RFC" value="8878"/>
<seriesInfo name='DOI' value='10.17487/RFC5246'/> <seriesInfo name="DOI" value="10.17487/RFC8878"/>
</reference> </reference>
</references>
<references>
<name>Informative References</name>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.R
FC.5246.xml"/>
</references>
</references> </references>
<section anchor="acknowledgements" numbered="false" toc="default">
<section anchor="acknowledgements" title="Acknowledgements"> <name>Acknowledgements</name>
<t>Certificate compression was originally introduced in the QUIC Crypto pr
<t>Certificate compression was originally introduced in the QUIC Crypto protocol otocol,
, designed by <contact fullname="Adam Langley"/> and <contact fullname="Wan-Teh
designed by Adam Langley and Wan-Teh Chang.</t> Chang" />.</t>
<t>This document has benefited from contributions and suggestions from <co
<t>This document has benefited from contributions and suggestions from David ntact fullname="David
Benjamin, Ryan Hamilton, Christian Huitema, Benjamin Kaduk, Ilari Liusvaara, Benjamin"/>, <contact fullname="Ryan Hamilton"/>, <contact fullname="Christian
Piotr Sikora, Ian Swett, Martin Thomson, Sean Turner and many others.</t> Huitema"/>, <contact fullname="Benjamin Kaduk"/>, <contact fullname="Ilari
Liusvaara"/>, <contact fullname="Piotr Sikora"/>, <contact fullname="Ian Swett"/
</section> >, <contact fullname="Martin Thomson"/>, <contact fullname="Sean Turner"/>, and
many others.</t>
</section>
</back> </back>
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