Network Working Group S. Raza
Internet-Draft J. Hoeglund
Intended status: Standards Track RISE AB
Expires: June 4, 2021 G. Selander
J. Mattsson
Ericsson AB
M. Furuhed
Nexus Group
December 01, 2020
CBOR Encoding of X.509 Certificates (CBOR Certificates)
draft-mattsson-cose-cbor-cert-compress-05
Abstract
This document specifies a CBOR encoding of X.509 certificates. The
resulting certificates are called CBOR Certificates. The CBOR
encoding supports a large subset of RFC 5280, while at the same time
significantly reduces the size of certificates compatible with RFC
7925 and IEEE 802.1AR (DevIDs). When used to re-encode DER encoded
X.509 certificates, the CBOR encoding can in many cases reduce the
size of RFC 7925 profiled certificates with over 50%. The CBOR
encoding can also be used encode "natively signed" CBOR certificates,
which does not require re-encoding for the signature to be verified.
The document also specifies COSE headers as well as a TLS certificate
type for CBOR certificates.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on June 4, 2021.
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Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions . . . . . . . . . . . . . . . . . . . 4
3. CBOR Encoding . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Message Fields . . . . . . . . . . . . . . . . . . . . . 5
3.2. Encoding of Extensions . . . . . . . . . . . . . . . . . 8
4. Compliance Requirements for Constrained IoT . . . . . . . . . 10
5. Legacy Considerations . . . . . . . . . . . . . . . . . . . . 11
6. Expected Certificate Sizes . . . . . . . . . . . . . . . . . 11
7. Natively Signed CBOR Certificates . . . . . . . . . . . . . . 12
8. Security Considerations . . . . . . . . . . . . . . . . . . . 12
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
9.1. CBOR Certificate Types Registry . . . . . . . . . . . . . 13
9.2. CBOR Attribute Type Registry . . . . . . . . . . . . . . 14
9.3. CBOR Extension Type Registry . . . . . . . . . . . . . . 14
9.4. CBOR Extended Key Usage Registry . . . . . . . . . . . . 15
9.5. CBOR General Name Registry . . . . . . . . . . . . . . . 16
9.6. CBOR Certificate Signature Algorithms Registry . . . . . 16
9.7. CBOR Certificate Public Key Algorithms Registry . . . . . 17
9.8. COSE Header Parameters Registry . . . . . . . . . . . . . 18
9.9. TLS Certificate Types Registry . . . . . . . . . . . . . 19
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
10.1. Normative References . . . . . . . . . . . . . . . . . . 19
10.2. Informative References . . . . . . . . . . . . . . . . . 20
Appendix A. Example CBOR Certificates . . . . . . . . . . . . . 21
A.1. Example RFC 7925 profiled X.509 Certificate . . . . . . . 21
A.2. Example HTPPS X.509 Certificate . . . . . . . . . . . . . 25
Appendix B. X.509 Certificate Profile, ASN.1 . . . . . . . . . . 27
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 29
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 29
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1. Introduction
One of the challenges with deploying a Public Key Infrastructure
(PKI) for the Internet of Things (IoT) is the size and parsing of
X.509 public key certificates [RFC5280], since those are not
optimized for constrained environments [RFC7228]. More compact
certificate representations are desirable. Due to the current PKI
usage of DER encoded X.509 certificates, keeping compatibility with
DER encoded X.509 is necessary at least for a transition period.
However, the use of a more compact encoding with the Concise Binary
Object Representation (CBOR) [RFC7049] reduces the certificate size
significantly which has known performance benefits in terms of
decreased communication overhead, power consumption, latency,
storage, etc.
CBOR is a data format designed for small code size and small message
size. CBOR builds on the JSON data model but extends it by e.g.
encoding binary data directly without base64 conversion. In addition
to the binary CBOR encoding, CBOR also has a diagnostic notation that
is readable and editable by humans. The Concise Data Definition
Language (CDDL) [RFC8610] provides a way to express structures for
protocol messages and APIs that use CBOR. [RFC8610] also extends the
diagnostic notation.
CBOR data items are encoded to or decoded from byte strings using a
type-length-value encoding scheme, where the three highest order bits
of the initial byte contain information about the major type. CBOR
supports several different types of data items, in addition to
integers (int, uint), simple values (e.g. null), byte strings (bstr),
and text strings (tstr), CBOR also supports arrays [] of data items,
maps {} of pairs of data items, and sequences of data items. For a
complete specification and examples, see [RFC7049], [RFC8610], and
[RFC8742].
RFC 7925 [RFC7925] and IEEE 802.1AR [IEEE-802.1AR] specify
certificate profiles for Internet of Things deployments which can be
applied to lightweight certificate based authentication with, e.g.,
TLS [RFC8446], DTLS [I-D.ietf-tls-dtls13], COSE [RFC8152], EDHOC
[I-D.ietf-lake-edhoc] or Compact TLS 1.3 [I-D.ietf-tls-ctls]. This
document specifies a CBOR encoding based on [X.509-IoT], which can
support large parts of [RFC5280]. The encoding support all [RFC7925]
and IEEE 802.1AR [IEEE-802.1AR] profiled X.509 certificates. Two
variants are defined using the same CBOR encoding and differing only
in what is being signed:
o An invertible CBOR re-encoding of DER encoded X.509 certificates
[RFC5280], which can be reversed to obtain the original DER
encoded X.509 certificate.
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o Natively signed CBOR certificates, which further optimizes the
performance in constrained environments but is not backwards
compatible with [RFC5280], see Section 7.
This document specifies COSE headers for use of the CBOR certificates
with COSE, see Section 9.8. The document also specifies a TLS
certificate type for use of the CBOR certificates with TLS (with or
without additional TLS certificate compression), see Section 9.9.
2. Notational Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
This specification makes use of the terminology in [RFC5280],
[RFC7049], [RFC7228], and [RFC8610].
3. CBOR Encoding
This section specifies the content and encoding for CBOR
certificates, with the overall objective to produce a very compact
representation supporting large parts of [RFC5280], and everything in
[RFC7925] and [IEEE-802.1AR]. In the CBOR encoding, static fields
are elided, elliptic curve points and time values are compressed, OID
are replaced with short integers, and redundant encoding is removed.
Combining these different components reduces the certificate size
significantly, which is not possible with general purpose
compressions algorithms, see Figure 2.
The CBOR certificate can be either a CBOR re-encoding of a DER
encoded X.509 certificate, in which case the signature is calculated
on the DER encoded ASN.1 data in the X.509 certificate, or a natively
signed CBOR certificate, in which case the signature is calculated
directly on the CBOR encoded data (see Section 7). In both cases the
certificate content is adhering to the restrictions given by
[RFC5280]. The re-encoding is known to work with DER encoded
certificates but might work with other canonical encodings. The re-
encoding does not work for BER encoded certificates.
In the encoding described below, the order of elements in arrays are
always encoded in the same order as the elements or the corresponding
SEQUENCE or SET in the DER encoding.
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3.1. Message Fields
The X.509 fields and their CBOR encodings are listed below, and used
in the definition of CBOR Certificates, see Figure 1.
CBOR certificates are defined in terms of DER encoded [RFC5280] X.509
certificates:
o version. The 'version' field is encoded in the
'cborCertificateType' CBOR int. The field 'cborCertificateType'
also indicates the type of the CBOR certificate. Currently, the
type can be a natively signed CBOR certificate following X.509 v3
(cborCertificateType = 0) or a CBOR re-encoded X.509 v3 DER
certificate (cborCertificateType = 1), see Section 9.1.
o serialNumber. The 'serialNumber' INTEGER value field is encoded
as the unwrapped CBOR positive bignum (~biguint)
'certificateSerialNumber'. Any leading 0x00 byte (to indicate
that the number is not negative) is therefore omitted.
o signature. The 'signature' field is always the same as the
'signatureAlgorithm' field and therefore omitted from the CBOR
encoding.
o issuer. In the general case, the sequence of
'RelativeDistinguishedName' is encoded as a CBOR array of CBOR
arrays of Attributes, where each Attribute type and value is
encoded as a (CBOR int, CBOR text string) pair. Each
AttributeType is encoded as a CBOR int (see Figure 4). The
AttributeType id-emailAddress is always an IA5String. For the
other AttributeTypes, the sign is used to represent the character
string type; positive for utf8String, negative for
printableString. In natively signed CBOR certificates all strings
are utf8String and the sign has no meaning. The string types
teletexString, universalString, and bmpString are not supported.
If Name contains a single Attribute containing an utf8String
encoded 'common name' it is encoded as a CBOR text string. If the
text string contains an EUI-64 of the form "HH-HH-HH-HH-HH-HH-HH-
HH" where 'H' is one of the symbol '0'-'9' or 'A'-'F' it is
encoded as a CBOR byte string of length 8 instead. EUI-64 mapped
from a 48-bit MAC address (i.e. of the form "HH-HH-HH-FF-FE-HH-HH-
HH) is encoded as a CBOR byte string of length 6.
o validity. The 'notBefore' and 'notAfter' fields are encoded as
unwrapped CBOR epoch-based date/time (~time) where the tag content
is an unsigned integer. In POSIX time, leap seconds are ignored,
with a leap second having the same POSIX time as the second before
it. Compression of X.509 certificates with the time 23:59:60 UTC
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is therefore not supported. Note that RFC 5280 mandates encoding
of dates through the year 2049 as UTCTime, and later dates as
GeneralizedTime. The value "99991231235959Z" (no expiration date)
is encoded as CBOR null.
o subject. The 'subject' is encoded exactly like issuer.
o subjectPublicKeyInfo. The 'algorithm' field is encoded as the
CBOR int 'subjectPublicKeyAlgorithm' (see Section 9.7) or a CBOR
OID tag [I-D.ietf-cbor-tags-oid] . Algorithms with parameters are
not supported except id-ecPublicKey with named curves and the RSA
algorithms that use parameters = NULL. For id-ecPublicKey the
namedCurve parameter is encoded in the CBOR int. The
'subjectPublicKey' BIT STRING value field is encoded as a CBOR
byte string. This specification assumes the BIT STRING has zero
unused bits and the unused bits byte is omitted. Uncompressed
public keys of type id-ecPublicKey are point compressed as defined
in Section 2.3.3 of [SECG]. If a DER encoded certificate with a
point compressed public key of type id-ecPublicKey is CBOR
encoded, the octets 0xfe and 0xfd are used instead of 0x02 and
0x03 in the CBOR encoding to represent even and odd y-coordinate,
respectively.
o issuerUniqueID. Not supported.
o subjectUniqueID. Not supported.
o extensions. The 'extensions' field is encoded as a CBOR array
where each extension is encoded as either a CBOR int (see
Section 9.3) followed by an optional CBOR item of any type or a
CBOR OID tag [I-D.ietf-cbor-tags-oid] followed by a CBOR bool
encoding 'critical' and the DER encoded value of the 'extnValue'
encoded as a CBOR byte string. If the array contains exactly two
ints and the absolute value of the first int is 2, the array is
omitted and the extensions is encoded as a single CBOR int with
the absolute value of the second int and the sign of the first
int. Extensions are encoded as specified in Section 3.2. The
extensions mandated to be supported by [RFC7925] and
[IEEE-802.1AR] are given special treatment. An omitted
'extensions' field is encoded as an empty CBOR array.
o signatureAlgorithm. The 'signatureAlgorithm' field is encoded as
a CBOR int (see Section 9.6) or a CBOR OID tag
[I-D.ietf-cbor-tags-oid]. Algorithms with parameters are not
supported except RSA algorithms that use parameters = NULL.
o signatureValue. The 'signatureValue' BIT STRING value field is
encoded as the CBOR byte string issuerSignatureValue. This
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specification assumes the BIT STRING has zero unused bits and the
unused bits byte is omitted. ECDSA signatures are given special
treatment. For ECDSA signatures the SEQUENCE and INTEGER type and
length fields are omitted and the two INTEGER value fields are
padded to the fixed length L = ceil( log2(n) / 8 ), where n is the
size of the largest prime-order subgroup. For secp256r1,
secp384r1, and secp521r1, L is 32, 48, and 66 respectively. For
natively signed CBOR certificates the signatureValue is calculated
over the CBOR sequence TBSCertificate.
The following Concise Data Definition Language (CDDL) defines
CBORCertificate and TBSCertificate, which are encoded as CBOR
Sequences [RFC8742]. The member names therefore only have
documentary value.
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; The elements of the following array are to be used in a CBOR Sequence:
CBORCertificate = [
TBSCertificate,
issuerSignatureValue : bytes,
]
TBSCertificate = (
cborCertificateType : int,
certificateSerialNumber : CertificateSerialNumber,
issuer : Name,
validityNotBefore : Time,
validityNotAfter : Time / null,
subject : Name,
subjectPublicKeyAlgorithm : Algorithm,
subjectPublicKey : bytes,
extensions : Extensions,
issuerSignatureAlgorithm : Algorithm,
)
CertificateSerialNumber = ~biguint
Name = [ * [ + Attribute ] ] / text / bytes
Attribute = ( attributeType : int, attributeValue : text )
Time = ~time
Algorithm = int / oid
Extensions = [ * Extension ] / int
Extension = (
extensionID : int / oid,
? critical : bool, ; present if and only if extensionID is an oid
extensionValue : any, ; type known from extensionID
)
Figure 1: CDDL for CBORCertificate.
3.2. Encoding of Extensions
EDITOR'S NOTE: The current specification encodes many common
extensions with a DER encoded byte string. It should be discussed if
more or all commonly active extensions should be natively encoded
with CBOR. Would a specific CBOR encoding have to be specified for
each extension or can a general CBOR encoding that apply to all
remaining extensions be specified?
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This section details the encoding of the 'extensions' field. The
'extensions' field is encoded as a CBOR array where each extensionID
is encoded as either a CBOR int or a CBOR OID tag. If 'extensionID'
is encoded an int (see Section 9.3),the sign is used to encode if the
extension is critical and the 'critical' field is omitted. Critical
extensions are encoded with a positive sign and non-critical
extensions are encoded with a negative sign.
The 'extnValue' OCTET STREAM value field is encoded as the CBOR byte
string 'extensionValue' except for the extensions specified below.
The 'extensionValue' for the extensions mandated to be supported by
[RFC7925] and [IEEE-802.1AR] are encoded as follows:
o basicConstraints. If 'cA' = false then extensionValue = -2, if
'cA' = true and 'pathLenConstraint' is not present then
extensionValue = -1, and if 'cA' = true and 'pathLenConstraint' is
present then extensionValue = pathLenConstraint.
o keyUsage. The 'KeyUsage' BIT STRING is interpreted as an unsigned
integer n in network byte order and encoded as a CBOR int.
o extKeyUsage. extensionValue is encoded as an array of CBOR ints
(see Section 9.4) or CBOR OID tags [I-D.ietf-cbor-tags-oid] where
each int or OID tag encodes a key usage purpose. If the array
contains a single int, the array is omitted.
ExtValueEKU = [ + int / oid ] / int
o subjectAltName. extensionValue is encoded as an array of (int,
any) pairs where each pair encodes a general name (see
Section 9.5). If subjectAltName contains exactly one dNSName, the
array and the int are omitted and extensionValue is the dNSName
encoded as a CBOR text string. In addition to the general names
defined in [RFC5280], the hardwareModuleName type of otherName has
been given its own int due to its mandatory use in IEEE 802.1AR.
When 'otherName + hardwareModuleName' is used, then [ oid, bytes ]
is used to identify the pair ( hwType, hwSerialEntries ) directly
as specified in [RFC4108].
GeneralNames = [ + GeneralName ] / text
GeneralName = ( GeneralNameType : int, GeneralNameValue : any )
o authorityKeyIdentifier. extensionValue is encoded as an array
where the value of the 'keyIdentifier' is encoded as a CBOR byte
string, 'GeneralNames' is encoded like in subjectAltName, and
'AuthorityCertSerialNumber' is encoded as ~biguint exactly like
certificateSerialNumber.
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KeyIdentifier = bytes
o subjectKeyIdentifier. extensionValue is the value of the
'keyIdentifier' field encoded as a CBOR byte string.
o cRLDistributionPoints. If the cRLDistributionPoints is a sequence
of DistributionPointName, it is encoded like subjectAltName, with
the difference that if cRLDistributionPoints contains exactly one
uniformResourceIdentifier, the the array and the int are omitted
and extensionValue is the uniformResourceIdentifier encoded as a
CBOR text string.
o authorityInfoAccess. If authorityInfoAccess consist of only
uniformResourceIdentifiers it is encoded as an array of uris.
ExtValueAIA = [ + ( ocsp : 1 // caIssuers : 2 , uri : text ) ]
3.2.1. Example Encoding of Extensions
The examples below use values from Section 9.3, Section 9.4, and
Section 9.5:
o A critical basicConstraints ('cA' = true) without
pathLenConstraint is encoded as the two CBOR ints -1, -1.
o A non-critical keyUsage with digitalSignature and keyAgreement
asserted is encoded as the two CBOR ints 2, 17 (2^0 + 2^4 = 17).
o A non-critical extKeyUsage containing id-kp-codeSigning and id-kp-
OCSPSigning is encoded as the CBOR int 3 followed by the CBOR
array [ 3, 6 ].
o A non-critical subjectAltName containing only the dNSName
example.com is encoded as the CBOR int 4 followed by the CBOR text
string "example.com".
Thus, the extension field of a certificate containing all of the
above extensions in the given order would be encoded as the CBOR
array [ -1, -1, 2, 17, 3, [ 3, 6 ], 4, "example.com" ].
4. Compliance Requirements for Constrained IoT
For general purpose applications, the normative requirements of
[RFC5280] applies. This section describes the mandatory to implement
algorithms and OIDs for constrained IoT application; the values of
the OIDs including certificate fields and extensions, time format,
attributes in distinguished names, etc.
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TODO: Write this section
5. Legacy Considerations
CBOR certificates can be deployed with legacy X.509 certificates and
CA infrastructure. In order to verify the signature, the CBOR
certificate is used to recreate the original X.509 data structure to
be able to verify the signature.
For protocols like TLS/DTLS 1.2, where the handshake is sent
unencrypted, the actual encoding and compression can be done at
different locations depending on the deployment setting. For
example, the mapping between CBOR certificate and standard X.509
certificate can take place in a 6LoWPAN border gateway which allows
the server side to stay unmodified. This case gives the advantage of
the low overhead of a CBOR certificate over a constrained wireless
links. The conversion to X.509 within an IoT device will incur a
computational overhead, however, measured in energy this is likely to
be negligible compared to the reduced communication overhead.
For the setting with constrained server and server-only
authentication, the server only needs to be provisioned with the CBOR
certificate and does not perform the conversion to X.509. This
option is viable when client authentication can be asserted by other
means.
For protocols like IKEv2, TLS/DTLS 1.3, and EDHOC, where certificates
are encrypted, the proposed encoding needs to be done fully end-to-
end, through adding the encoding/decoding functionality to the
server.
6. Expected Certificate Sizes
The CBOR encoding of the sample certificate given in Appendix A
results in the numbers shown in Figure 2. After [RFC7925] profiling,
most duplicated information has been removed, and the remaining text
strings are minimal in size. Therefore, the further size reduction
reached with general compression mechanisms will be small, mainly
corresponding to making the ASN.1 encoding more compact. The zlib
number was calculated with zlib-flate.
zlib-flate -compress < cert.der > cert.compressed
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+------------------+--------------+------------+--------------------+
| | RFC 7925 | zlib | CBOR Certificate |
+------------------+---------------------------+--------------------+
| Certificate Size | 314 | 295 | 138 |
+------------------+--------------+------------+--------------------+
Figure 2: Comparing Sizes of Certificates (bytes)
7. Natively Signed CBOR Certificates
The difference between CBOR encoded X.509 certificate and natively
signed CBOR certificate is that the signature is calculated over the
CBOR encoding of the CBOR sequence TBSCertficate rather than the DER
encoded ASN.1 data. This removes entirely the need for ASN.1 DER and
base64 encodings which reduces the processing in the authenticating
devices, and avoids known complexities and security issues with these
encodings.
Natively signed CBOR certificates can be applied in devices that are
only required to authenticate to natively signed CBOR certificate
compatible servers. This is not a major restriction for many IoT
deployments, where the parties issuing and verifying certificates can
be a restricted ecosystem which not necessarily involves public CAs.
CBOR encoded X.509 certificates provides an intermediate step between
[RFC7925] or [IEEE-802.1AR] profiled X.509 certificates and natively
signed CBOR certificates: An implementation of CBOR encoded X.509
certificates contains both the CBOR encoding of the X.509 certificate
and the signature operations sufficient for natively signed CBOR
certificates.
The natively signed approach based on DER encoded X.509 certificates
described in this document has also other benefits. For example, a
CA can use existing ASN.1 machinery to create a DER encoded
certificate, the DER encoded certificate can then be transformed to
CBOR before signing.
8. Security Considerations
The CBOR profiling of X.509 certificates does not change the security
assumptions needed when deploying standard X.509 certificates but
decreases the number of fields transmitted, which reduces the risk
for implementation errors.
The use of natively signed CBOR certificates removes the need for
ASN.1 encoding, which is a rich source of security vulnerabilities.
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Conversion between the certificate formats can be made in constant
time to reduce risk of information leakage through side channels.
The mechanism in this draft does not reveal any additional
information compared to X.509. Because of difference in size, it
will be possible to detect that this profile is used. The gateway
solution described in Section 5 requires unencrypted certificates and
is not recommended.
9. IANA Considerations
This document creates several new registries under the new heading
"CBOR Certificate". For all items, the 'Reference' field points to
this document.
The expert reviewers for the registries defined in this document are
expected to ensure that the usage solves a valid use case that could
not be solved better in a different way, that it is not going to
duplicate one that is already registered, and that the registered
point is likely to be used in deployments. They are furthermore
expected to check the clarity of purpose and use of the requested
code points. Experts should take into account the expected usage of
entries when approving point assignment, and the length of the
encoded value should be weighed against the number of code points
left that encode to that size and the size of device it will be used
on. Values in the interval [-24, 23] have a 1 byte encodings, other
values in the interval [-256, 255] have a 2 byte encodings, and the
remaning values in the interval [-65536, 65535] have 3 byte
encodings.
9.1. CBOR Certificate Types Registry
IANA has created a new registry titled "CBOR Certificate Types" under
the new heading "CBOR Certificate". For values in the interval [-24,
23] the registration procedure is "IETF Review" and "Expert Review".
For all other values the registration procedure is "Expert Review".
The columns of the registry are Value, Description, and Reference,
where Value is an integer, and the other columns are text strings.
The initial contents of the registry are:
+-------+-----------------------------------------------------+
| Value | Description |
+=======+=====================================================+
| 0 | Natively Signed CBOR Certificate following X.509 v3 |
| 1 | CBOR re-encoding of X.509 v3 Certificate |
+-------+-----------------------------------------------------+
Figure 3: CBOR Certificate Types
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9.2. CBOR Attribute Type Registry
IANA has created a new registry titled "CBOR Attribute Type Registry"
under the new heading "CBOR Certificate". The columns of the
registry are Value, X.509 Attribute Type, and Reference, where Value
is an integer, and the other columns are text strings. Only non-
negative values can be registered. For values in the interval [0,
23] the registration procedure is "IETF Review" and "Expert Review".
For all other values the registration procedure is "Expert Review".
The initial contents of the registry are:
+-------+---------------------------------------+
| Value | X.509 Attribute Type |
+=======+=======================================+
| 0 | id-emailAddress |
| 1 | id-at-commonName |
| 2 | id-at-surname |
| 3 | id-at-serialNumber |
| 4 | id-at-countryName |
| 5 | id-at-localityName |
| 6 | id-at-stateOrProvinceName |
| 7 | id-at-organizationName |
| 8 | id-at-organizationalUnitName |
| 9 | id-at-title |
| 10 | id-at-givenName |
| 11 | id-at-initials |
| 12 | id-at-generationQualifier |
| 13 | id-at-dnQualifier |
| 14 | id-at-pseudonym |
| 15 | id-at-organizationIdentifier |
+-------+---------------------------------------+
Figure 4: CBOR Attribute Type Registry
9.3. CBOR Extension Type Registry
IANA has created a new registry titled "CBOR Extension Type Registry"
under the new heading "CBOR Certificate". The columns of the
registry are Value, X.509 Extension Type, and Reference, where Value
is an integer, and the other columns are text strings. Only positive
values can be registered. For values in the interval [1, 23] the
registration procedure is "IETF Review" and "Expert Review". For all
other values the registration procedure is "Expert Review". The
initial contents of the registry are:
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+-------+-------------------------------------+------------------+
| Value | X.509 Extension Type | extensionValue |
+=======+=====================================+==================+
| 1 | id-ce-basicConstraints | int |
| 2 | id-ce-keyUsage | int |
| 3 | id-ce-extKeyUsage | ExtValueEKU |
| 4 | id-ce-subjectAltName | GeneralNames |
| 5 | id-ce-authorityKeyIdentifier | ExtValueAKI |
| 6 | id-ce-subjectKeyIdentifier | KeyIdentifier |
| 7 | id-ce-certificatePolicies | bytes |
| 8 | id-ce-cRLDistributionPoints | GeneralNames |
| 9 | id-pe-authorityInfoAccess | ExtValueAIA |
| 10 | SCT List (1.3.6.1.4.1.11129.2.4.2) | bytes |
| 248 | id-ce-nameConstraints | bytes |
| 249 | id-ce-policyConstraints | bytes |
| 250 | id-ce-inhibitAnyPolicy | bytes |
| 251 | id-ce-policyMappings | bytes |
| 252 | id-ce-issuerAltName | GeneralNames |
| 253 | id-ce-subjectDirectoryAttributes | bytes |
| 254 | id-ce-freshestCRL | bytes |
| 255 | id-pe-subjectInfoAccess | bytes |
+-------+-------------------------------------+------------------+
Figure 5: CBOR Extension Type Registry
9.4. CBOR Extended Key Usage Registry
IANA has created a new registry titled "CBOR Extended Key Usage
Registry" under the new heading "CBOR Certificate". The columns of
the registry are Value, Extended Key Usage Purpose, and Reference,
where Value is an integer, and the other columns are text strings.
For values in the interval [-24, 23] the registration procedure is
"IETF Review" and "Expert Review". For all other values the
registration procedure is "Expert Review". The initial contents of
the registry are:
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+-------+---------------------------------------+
| Value | Extended Key Usage |
+=======+=======================================+
| 0 | anyExtendedKeyUsage |
| 1 | id-kp-serverAuth |
| 2 | id-kp-clientAuth |
| 3 | id-kp-codeSigning |
| 4 | id-kp-emailProtection |
| 5 | id-kp-timeStamping |
| 6 | id-kp-OCSPSigning |
+-------+---------------------------------------+
Figure 6: CBOR Extended Key Usage Registry
9.5. CBOR General Name Registry
IANA has created a new registry titled "CBOR General Name Registry"
under the new heading "CBOR Certificate". The columns of the
registry are Value, General Name, and Reference, where Value is an
integer, and the other columns are text strings. For values in the
interval [-24, 23] the registration procedure is "IETF Review" and
"Expert Review". For all other values the registration procedure is
"Expert Review". The initial contents of the registry are:
+-------+-----------------------------------+------------------+
| Value | General Name Type | Value |
+=======+===================================+==================+
| -1 | otherName + hardwareModuleName | [ oid, bytes ] |
| 0 | otherName | [ oid, bytes ] |
| 1 | rfc822Name | text |
| 2 | dNSName | text |
| 4 | directoryName | Name |
| 6 | uniformResourceIdentifier | text |
| 7 | iPAddress | bytes |
| 8 | registeredID | oid |
+-------+-----------------------------------+------------------+
Figure 7: CBOR General Name Registry
9.6. CBOR Certificate Signature Algorithms Registry
IANA has created a new registry titled "CBOR Certificate Signature
Algorithms" under the new heading "CBOR Certificate". For values in
the interval [-24, 23] the registration procedure is "IETF Review"
and "Expert Review". For all other values the registration procedure
is "Expert Review". The columns of the registry are Value, X.509
Algorithm, and Reference, where Value is an integer, and the other
columns are text strings. The initial contents of the registry are:
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+-------+---------------------------------------+
| Value | X.509 Signature Algorithm |
+=======+=======================================+
| -256 | sha1WithRSAEncryption |
| -255 | ecdsa-with-SHA1 |
| 1 | sha256WithRSAEncryption |
| 2 | sha384WithRSAEncryption |
| 3 | sha512WithRSAEncryption |
| 4 | id-RSASSA-PSS-SHAKE128 |
| 5 | id-RSASSA-PSS-SHAKE256 |
| 6 | ecdsa-with-SHA256 |
| 7 | ecdsa-with-SHA384 |
| 8 | ecdsa-with-SHA512 |
| 9 | id-ecdsa-with-shake128 |
| 10 | id-ecdsa-with-shake256 |
| 11 | id-Ed25519 |
| 12 | id-Ed448 |
| 13 | id-alg-hss-lms-hashsig |
| 14 | id-alg-xmss |
| 15 | id-alg-xmssmt |
| 245 | sha224WithRSAEncryption |
| 246 | id-rsassa-pkcs1-v1_5-with-sha3-224 |
| 247 | id-rsassa-pkcs1-v1_5-with-sha3-256 |
| 248 | id-rsassa-pkcs1-v1_5-with-sha3-384 |
| 249 | id-rsassa-pkcs1-v1_5-with-sha3-512 |
| 251 | ecdsa-with-SHA224 |
| 252 | id-ecdsa-with-sha3-224 |
| 253 | id-ecdsa-with-sha3-256 |
| 254 | id-ecdsa-with-sha3-384 |
| 255 | id-ecdsa-with-sha3-512 |
+-------+---------------------------------------+
Figure 8: CBOR Certificate Signature Algorithms
9.7. CBOR Certificate Public Key Algorithms Registry
IANA has created a new registry titled "CBOR Certificate Public Key
Algorithms" under the new heading "CBOR Certificate". For values in
the interval [-24, 23] the registration procedure is "IETF Review"
and "Expert Review". For all other values the registration procedure
is "Expert Review". The columns of the registry are Value, X.509
Algorithm, and Reference, where Value is an integer, and the other
columns are text strings. The initial contents of the registry are:
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+-------+---------------------------------------+
| Value | X.509 Public Key Algorithm |
+=======+=======================================+
| 0 | rsaEncryption |
| 1 | id-ecPublicKey + secp256r1 |
| 2 | id-ecPublicKey + secp384r1 |
| 3 | id-ecPublicKey + secp521r1 |
| 4 | id-X25519 |
| 5 | id-X448 |
| 6 | id-Ed25519 |
| 7 | id-Ed448 |
| 8 | id-alg-hss-lms-hashsig |
| 9 | id-alg-xmss |
| 10 | id-alg-xmssmt |
+-------+---------------------------------------+
Figure 9: CBOR Certificate Public Key Algorithms
9.8. COSE Header Parameters Registry
This document registers the following entries in the "COSE Header
Parameters" registry under the "CBOR Object Signing and Encryption
(COSE)" heading. The formatting and processing are the same as the
corresponding x5bag, x5chain, x5t, and x5u defined in
[I-D.ietf-cose-x509] except that the certificates are CBOR encoded
instead of DER encoded. Note that certificates can also be
identified with a 'kid' header parameter by storing 'kid' and the
associated bag or chain in a dictionary.
+-----------+-------+----------------+---------------------+
| Name | Label | Value Type | Description |
+===========+=======+================+=====================+
| c5bag | TBD1 | COSE_X509 | An unordered bag of |
| | | | CBOR certificates |
+-----------+-------+----------------+---------------------+
| c5chain | TBD2 | COSE_X509 | An ordered chain of |
| | | | CBOR certificates |
+-----------+-------+----------------+---------------------+
| c5t | TBD3 | COSE_CertHash | Hash of an |
| | | | CBOR certificate |
+-----------+-------+----------------+---------------------+
| c5u | TBD4 | uri | URI pointing to a |
| | | | CBOR certificate |
+-----------+-------+----------------+---------------------+
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9.9. TLS Certificate Types Registry
This document registers the following entry in the "TLS Certificate
Types" registry under the "Transport Layer Security (TLS) Extensions"
heading. The new certificate type can be used with addtional TLS
certificate compression [I-D.ietf-tls-certificate-compression].
EDITOR'S NOTE: The TLS registrations should be discussed and approved
by the TLS WG at a later stage. When COSE WG has adopted work on
CBOR certificates, it could perhaps be presented in the TLS WG. The
TLS WG might e.g. want a separate draft in the TLS WG.
+-------+------------------+-------------+---------+
| Value | Name | Recommended | Comment |
+=======+==================+=============+=========+
| TBD5 | CBOR Certificate | Y | |
+-------+------------------+-------------+---------+
10. References
10.1. Normative References
[I-D.ietf-cbor-tags-oid]
Bormann, C. and S. Leonard, "Concise Binary Object
Representation (CBOR) Tags for Object Identifiers", draft-
ietf-cbor-tags-oid-03 (work in progress), November 2020.
[I-D.ietf-cose-x509]
Schaad, J., "CBOR Object Signing and Encryption (COSE):
Header parameters for carrying and referencing X.509
certificates", draft-ietf-cose-x509-07 (work in progress),
September 2020.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4108] Housley, R., "Using Cryptographic Message Syntax (CMS) to
Protect Firmware Packages", RFC 4108,
DOI 10.17487/RFC4108, August 2005,
<https://www.rfc-editor.org/info/rfc4108>.
[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,
<https://www.rfc-editor.org/info/rfc5280>.
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[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <https://www.rfc-editor.org/info/rfc7049>.
[RFC8152] Schaad, J., "CBOR Object Signing and Encryption (COSE)",
RFC 8152, DOI 10.17487/RFC8152, July 2017,
<https://www.rfc-editor.org/info/rfc8152>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/info/rfc8610>.
[RFC8742] Bormann, C., "Concise Binary Object Representation (CBOR)
Sequences", RFC 8742, DOI 10.17487/RFC8742, February 2020,
<https://www.rfc-editor.org/info/rfc8742>.
[SECG] "Elliptic Curve Cryptography, Standards for Efficient
Cryptography Group, ver. 2", 2009,
<https://secg.org/sec1-v2.pdf>.
10.2. Informative References
[I-D.ietf-lake-edhoc]
Selander, G., Mattsson, J., and F. Palombini, "Ephemeral
Diffie-Hellman Over COSE (EDHOC)", draft-ietf-lake-
edhoc-02 (work in progress), November 2020.
[I-D.ietf-tls-certificate-compression]
Ghedini, A. and V. Vasiliev, "TLS Certificate
Compression", draft-ietf-tls-certificate-compression-10
(work in progress), January 2020.
[I-D.ietf-tls-ctls]
Rescorla, E., Barnes, R., and H. Tschofenig, "Compact TLS
1.3", draft-ietf-tls-ctls-01 (work in progress), November
2020.
[I-D.ietf-tls-dtls13]
Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version
1.3", draft-ietf-tls-dtls13-39 (work in progress),
November 2020.
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[I-D.ietf-uta-tls13-iot-profile]
Tschofenig, H. and T. Fossati, "TLS/DTLS 1.3 Profiles for
the Internet of Things", draft-ietf-uta-tls13-iot-
profile-00 (work in progress), June 2020.
[IEEE-802.1AR]
Institute of Electrical and Electronics Engineers, .,
"IEEE Standard for Local and metropolitan area networks-
Secure Device Identity", IEEE Standard 802.1AR-2018 ,
August 2018,
<https://standards.ieee.org/standard/802_1AR-2018.html>.
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>.
[RFC7925] Tschofenig, H., Ed. and T. Fossati, "Transport Layer
Security (TLS) / Datagram Transport Layer Security (DTLS)
Profiles for the Internet of Things", RFC 7925,
DOI 10.17487/RFC7925, July 2016,
<https://www.rfc-editor.org/info/rfc7925>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[X.509-IoT]
Forsby, F., Furuhed, M., Papadimitratos, P., and S. Raza,
"Lightweight X.509 Digital Certificates for the Internet
of Things.", Springer, Cham. Lecture Notes of the
Institute for Computer Sciences, Social Informatics and
Telecommunications Engineering, vol 242., July 2018,
<https://doi.org/10.1007/978-3-319-93797-7_14>.
Appendix A. Example CBOR Certificates
A.1. Example RFC 7925 profiled X.509 Certificate
Example of [RFC7925] profiled X.509 certificate parsed with OpenSSL.
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Certificate:
Data:
Version: 3 (0x2)
Serial Number: 128269 (0x1f50d)
Signature Algorithm: ecdsa-with-SHA256
Issuer: CN=RFC test CA
Validity
Not Before: Jan 1 00:00:00 2020 GMT
Not After : Feb 2 00:00:00 2021 GMT
Subject: CN=01-23-45-FF-FE-67-89-AB
Subject Public Key Info:
Public Key Algorithm: id-ecPublicKey
Public-Key: (256 bit)
pub:
04:b1:21:6a:b9:6e:5b:3b:33:40:f5:bd:f0:2e:69:
3f:16:21:3a:04:52:5e:d4:44:50:b1:01:9c:2d:fd:
38:38:ab:ac:4e:14:d8:6c:09:83:ed:5e:9e:ef:24:
48:c6:86:1c:c4:06:54:71:77:e6:02:60:30:d0:51:
f7:79:2a:c2:06
ASN1 OID: prime256v1
NIST CURVE: P-256
X509v3 extensions:
X509v3 Key Usage:
Digital Signature
Signature Algorithm: ecdsa-with-SHA256
30:44:02:20:44:5d:79:8c:90:e7:f5:00:dc:74:7a:65:4c:ec:
6c:fa:6f:03:72:76:e1:4e:52:ed:07:fc:16:29:4c:84:66:0d:
02:20:5a:33:98:5d:fb:d4:bf:dd:6d:4a:cf:38:04:c3:d4:6e:
bf:3b:7f:a6:26:40:67:4f:c0:35:4f:a0:56:db:ae:a6
The DER encoding of the above certificate is 314 bytes.
30 82 01 36 30 81 DE A0 03 02 01 02 02 03 01 F5 0D 30 0A 06 08 2A 86
48 CE 3D 04 03 02 30 16 31 14 30 12 06 03 55 04 03 0C 0B 52 46 43 20
74 65 73 74 20 43 41 30 1E 17 0D 32 30 30 31 30 31 30 30 30 30 30 30
5A 17 0D 32 31 30 32 30 32 30 30 30 30 30 30 5A 30 22 31 20 30 1E 06
03 55 04 03 0C 17 30 31 2D 32 33 2D 34 35 2D 46 46 2D 46 45 2D 36 37
2D 38 39 2D 41 42 30 59 30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 86
48 CE 3D 03 01 07 03 42 00 04 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E
69 3F 16 21 3A 04 52 5E D4 44 50 B1 01 9C 2D FD 38 38 AB AC 4E 14 D8
6C 09 83 ED 5E 9E EF 24 48 C6 86 1C C4 06 54 71 77 E6 02 60 30 D0 51
F7 79 2A C2 06 A3 0F 30 0D 30 0B 06 03 55 1D 0F 04 04 03 02 07 80 30
0A 06 08 2A 86 48 CE 3D 04 03 02 03 47 00 30 44 02 20 44 5D 79 8C 90
E7 F5 00 DC 74 7A 65 4C EC 6C FA 6F 03 72 76 E1 4E 52 ED 07 FC 16 29
4C 84 66 0D 02 20 5A 33 98 5D FB D4 BF DD 6D 4A CF 38 04 C3 D4 6E BF
3B 7F A6 26 40 67 4F C0 35 4F A0 56 DB AE A6
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A.1.1. Example CBOR Certificate Encoding
The CBOR encoding of the same X.509 certificate is shown below in
CBOR diagnostic format.
/This defines a CBOR Sequence (RFC 8742):/
1,
h'01f50d',
"RFC test CA",
1577836800,
1612224000,
h'0123456789AB',
1,
h'02B1216AB96E5B3B3340F5BDF02E693F16213A04525ED44450
B1019C2DFD3838AB',
1,
6,
h'445D798C90E7F500DC747A654CEC6CFA6F037276E14E52ED07
FC16294C84660D5A33985DFBD4BFDD6D4ACF3804C3D46EBF3B
7FA62640674FC0354FA056DBAEA6
The size of the CBOR encoding (CBOR sequence) is 138 bytes.
01
43 01 F5 0D
6B 52 46 43 20 74 65 73 74 20 43 41
1A 5E 0B E1 00
1A 60 18 96 00
46 01 23 45 67 89 AB
01
58 21 02 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52
5E D4 44 50 B1 01 9C 2D FD 38 38 AB
01
06
58 40 44 5D 79 8C 90 E7 F5 00 DC 74 7A 65 4C EC 6C FA 6F 03 72 76 E1
4E 52 ED 07 FC 16 29 4C 84 66 0D 5A 33 98 5D FB D4 BF DD 6D 4A CF 38
04 C3 D4 6E BF 3B 7F A6 26 40 67 4F C0 35 4F A0 56 DB AE A6
A.1.2. Example: Natively Signed CBOR Certificate
The corresponding natively signed CBOR certificate in CBOR diagnostic
format is identical, except for cborCertificateType and
signatureValue.
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/This defines a CBOR Sequence (RFC 8742):/
0,
h'01f50d',
"RFC test CA",
1577836800,
1612224000,
h'0123456789AB',
1,
h'02B1216AB96E5B3B3340F5BDF02E693F16213A04525ED44450
B1019C2DFD3838AB',
1,
6,
h'B27A0B781455F71B68290F6C2EC9A897F18FDE9B6C59575953
BC67268AB0E4DDE99D273E04E4715383AB2257C6AAA35284E5
ED18BDB91247E9F2C433136480B9'
The size of the CBOR encoding (CBOR sequence) is 138 bytes.
00
43 01 F5 0D
6B 52 46 43 20 74 65 73 74 20 43 41
1A 5E 0B E1 00
1A 60 18 96 00
46 01 23 45 67 89 AB
01
58 21 02 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52
5E D4 44 50 B1 01 9C 2D FD 38 38 AB
01
06
58 40 B2 7A 0B 78 14 55 F7 1B 68 29 0F 6C 2E C9 A8 97 F1 8F DE 9B 6C
59 57 59 53 BC 67 26 8A B0 E4 DD E9 9D 27 3E 04 E4 71 53 83 AB 22 57
C6 AA A3 52 84 E5 ED 18 BD B9 12 47 E9 F2 C4 33 13 64 80 B9
A.1.3. Example: Key Pair
All of the the above example certificate were signed and can be
verified with the following key pair where the private key is encoded
as in COSE [RFC8152].
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issuerPublicKeyAlgorithm :
1 (id-ecPublicKey + secp256r1)
issuerPublicKey :
h'02AE4CDB01F614DEFC7121285FDC7F5C6D1D42C95647F061BA0080DF678867845E'
issuerPrivateKey :
h'DC66B3415456D649429B53223DF7532B942D6B0E0842C30BCA4C0ACF91547BB2'
A.2. Example HTPPS X.509 Certificate
The DER encoding of the tools.ietf.org certificate is 1647 bytes.
30 82 06 6b 30 82 05 53 a0 03 02 01 02 02 09 00 a6 a5 5c 87 0e 39 b4
0e 30 0d 06 09 2a 86 48 86 f7 0d 01 01 0b 05 00 30 81 c6 31 0b 30 09
06 03 55 04 06 13 02 55 53 31 10 30 0e 06 03 55 04 08 13 07 41 72 69
7a 6f 6e 61 31 13 30 11 06 03 55 04 07 13 0a 53 63 6f 74 74 73 64 61
6c 65 31 25 30 23 06 03 55 04 0a 13 1c 53 74 61 72 66 69 65 6c 64 20
54 65 63 68 6e 6f 6c 6f 67 69 65 73 2c 20 49 6e 63 2e 31 33 30 31 06
03 55 04 0b 13 2a 68 74 74 70 3a 2f 2f 63 65 72 74 73 2e 73 74 61 72
66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72
79 2f 31 34 30 32 06 03 55 04 03 13 2b 53 74 61 72 66 69 65 6c 64 20
53 65 63 75 72 65 20 43 65 72 74 69 66 69 63 61 74 65 20 41 75 74 68
6f 72 69 74 79 20 2d 20 47 32 30 1e 17 0d 32 30 31 30 30 31 31 39 33
38 33 36 5a 17 0d 32 31 31 31 30 32 31 39 33 38 33 36 5a 30 3e 31 21
30 1f 06 03 55 04 0b 13 18 44 6f 6d 61 69 6e 20 43 6f 6e 74 72 6f 6c
20 56 61 6c 69 64 61 74 65 64 31 19 30 17 06 03 55 04 03 0c 10 2a 2e
74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67 30 82 01 22 30 0d 06 09 2a
86 48 86 f7 0d 01 01 01 05 00 03 82 01 0f 00 30 82 01 0a 02 82 01 01
00 b1 e1 37 e8 eb 82 d6 89 fa db f5 c2 4b 77 f0 2c 4a de 72 6e 3e 13
60 d1 a8 66 1e c4 ad 3d 32 60 e5 f0 99 b5 f4 7a 7a 48 55 21 ee 0e 39
12 f9 ce 0d ca f5 69 61 c7 04 ed 6e 0f 1d 3b 1e 50 88 79 3a 0e 31 41
16 f1 b1 02 64 68 a5 cd f5 4a 0a ca 99 96 35 08 c3 7e 27 5d d0 a9 cf
f3 e7 28 af 37 d8 b6 7b dd f3 7e ae 6e 97 7f f7 ca 69 4e cc d0 06 df
5d 27 9b 3b 12 e7 e6 fe 08 6b 52 7b 82 11 7c 72 b3 46 eb c1 e8 78 b8
0f cb e1 eb bd 06 44 58 dc 83 50 b2 a0 62 5b dc 81 b8 36 e3 9e 7c 79
b2 a9 53 8a e0 0b c9 4a 2a 13 39 31 13 bd 2c cf a8 70 cf 8c 8d 3d 01
a3 88 ae 12 00 36 1d 1e 24 2b dd 79 d8 53 01 26 ed 28 4f c9 86 94 83
4e c8 e1 14 2e 85 b3 af d4 6e dd 69 46 af 41 25 0e 7a ad 8b f2 92 ca
79 d9 7b 32 4f f7 77 e8 f9 b4 4f 23 5c d4 5c 03 ae d8 ab 3a ca 13 5f
5d 5d 5d a1 02 03 01 00 01 a3 82 02 e1 30 82 02 dd 30 0c 06 03 55 1d
13 01 01 ff 04 02 30 00 30 1d 06 03 55 1d 25 04 16 30 14 06 08 2b 06
01 05 05 07 03 01 06 08 2b 06 01 05 05 07 03 02 30 0e 06 03 55 1d 0f
01 01 ff 04 04 03 02 05 a0 30 3d 06 03 55 1d 1f 04 36 30 34 30 32 a0
30 a0 2e 86 2c 68 74 74 70 3a 2f 2f 63 72 6c 2e 73 74 61 72 66 69 65
6c 64 74 65 63 68 2e 63 6f 6d 2f 73 66 69 67 32 73 31 2d 32 34 32 2e
63 72 6c 30 63 06 03 55 1d 20 04 5c 30 5a 30 4e 06 0b 60 86 48 01 86
fd 6e 01 07 17 01 30 3f 30 3d 06 08 2b 06 01 05 05 07 02 01 16 31 68
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74 74 70 3a 2f 2f 63 65 72 74 69 66 69 63 61 74 65 73 2e 73 74 61 72
66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72
79 2f 30 08 06 06 67 81 0c 01 02 01 30 81 82 06 08 2b 06 01 05 05 07
01 01 04 76 30 74 30 2a 06 08 2b 06 01 05 05 07 30 01 86 1e 68 74 74
70 3a 2f 2f 6f 63 73 70 2e 73 74 61 72 66 69 65 6c 64 74 65 63 68 2e
63 6f 6d 2f 30 46 06 08 2b 06 01 05 05 07 30 02 86 3a 68 74 74 70 3a
2f 2f 63 65 72 74 69 66 69 63 61 74 65 73 2e 73 74 61 72 66 69 65 6c
64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72 79 2f 73 66
69 67 32 2e 63 72 74 30 1f 06 03 55 1d 23 04 18 30 16 80 14 25 45 81
68 50 26 38 3d 3b 2d 2c be cd 6a d9 b6 3d b3 66 63 30 2b 06 03 55 1d
11 04 24 30 22 82 10 2a 2e 74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67
82 0e 74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67 30 1d 06 03 55 1d 0e
04 16 04 14 ad 8a b4 1c 07 51 d7 92 89 07 b0 b7 84 62 2f 36 55 7a 5f
4d 30 82 01 06 06 0a 2b 06 01 04 01 d6 79 02 04 02 04 81 f7 04 81 f4
00 f2 00 77 00 f6 5c 94 2f d1 77 30 22 14 54 18 08 30 94 56 8e e3 4d
13 19 33 bf df 0c 2f 20 0b cc 4e f1 64 e3 00 00 01 74 e5 ac 71 13 00
00 04 03 00 48 30 46 02 21 00 8c f5 48 52 ce 56 35 43 39 11 cf 10 cd
b9 1f 52 b3 36 39 22 3a d1 38 a4 1d ec a6 fe de 1f e9 0f 02 21 00 bc
a2 25 43 66 c1 9a 26 91 c4 7a 00 b5 b6 53 ab bd 44 c2 f8 ba ae f4 d2
da f2 52 7c e6 45 49 95 00 77 00 5c dc 43 92 fe e6 ab 45 44 b1 5e 9a
d4 56 e6 10 37 fb d5 fa 47 dc a1 73 94 b2 5e e6 f6 c7 0e ca 00 00 01
74 e5 ac 72 3c 00 00 04 03 00 48 30 46 02 21 00 a5 e0 90 6e 63 e9 1d
4f dd ef ff 03 52 b9 1e 50 89 60 07 56 4b 44 8a 38 28 f5 96 dc 6b 28
72 6d 02 21 00 fc 91 ea ed 02 16 88 66 05 4e e1 8a 2e 53 46 c4 cc 51
fe b3 fa 10 a9 1d 2e db f9 91 25 f8 6c e6 30 0d 06 09 2a 86 48 86 f7
0d 01 01 0b 05 00 03 82 01 01 00 14 04 3f a0 be d2 ee 3f a8 6e 3a 1f
78 8e a0 4c 35 53 0f 11 06 1f ff 60 a1 6d 0b 83 e9 d9 2a db b3 3f 9d
b3 d7 e0 59 4c 19 a8 e4 19 a5 0c a7 70 72 77 63 d5 fe 64 51 0a d2 7a
d6 50 a5 8a 92 38 ec cb 2f 0f 5a c0 64 58 4d 5c 06 b9 73 63 68 27 8b
89 34 dc 79 c7 1d 3a fd 34 5f 83 14 41 58 49 80 68 29 80 39 8a 86 72
69 cc 79 37 ce e3 97 f7 dc f3 95 88 ed 81 03 29 00 d2 a2 c7 ba ab d6
3a 8e ca 09 0b d9 fb 39 26 4b ff 03 d8 8e 2d 3f 6b 21 ca 8a 7d d8 5f
fb 94 ba 83 de 9c fc 15 8d 61 fa 67 2d b0 c7 db 3d 25 0a 41 4a 85 d3
7f 49 46 37 3c f4 b1 75 d0 52 f3 dd c7 66 f1 4b fd aa 00 ed bf e4 7e
ed 01 ec 7b e4 f6 46 fc 31 fd 72 fe 03 d2 f2 65 af 4d 7e e2 81 9b 7a
fd 30 3c f5 52 f4 05 34 a0 8a 3e 19 41 58 c8 a8 e0 51 71 84 09 15 ae
ec a5 77 75 fa 18 f7 d5 77 d5 31 cc c7 2d
A.2.1. Example CBOR Certificate Encoding
The CBOR encoding of the X.509 certificate is shown below in CBOR
diagnostic format.
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/This defines a CBOR Sequence (RFC 8742):/
1,
h'A6A55C870E39B40E',
[
[-4, "US"],
[-6, "Arizona"],
[-5, "Scottsdale"],
[-7, "Starfield Technologies, Inc."],
[-8, "http://certs.starfieldtech.com/repository/"],
[-1, "Starfield Secure Certificate Authority - G2"]
],
1601581116,
1635881916,
[
[-8, "Domain Control Validated"],
[1, "*.tools.ietf.org"]
],
0,
h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
[
-1, -2,
3, [ 1, 2 ],
-2, 5,
8, "http://crl.starfieldtech.com/sfig2s1-242.crl",
7, h'305A304E060B6086480186FD6E01071701303F303D06082B060105050702011631687474703A2F2F6365727469666963617465732E737461726669656C64746563682E636F6D2F7265706F7369746F72792F3008060667810C010201',
9, [ 1, "http://ocsp.starfieldtech.com/", 2, "http://certificates.starfieldtech.com/repository/sfig2.crt" ],
5, h'254581685026383D3B2D2CBECD6AD9B63DB36663',
4, [ 2, "*.tools.ietf.org", 2, "tools.ietf.org" ],
6, h'AD8AB41C0751D7928907B0B784622F36557A5F4D',
10, h'0481F400F2007700F65C942FD1773022145418083094568EE34D131933BFDF0C2F200BCC4EF164E300000174E5AC711300000403004830460221008CF54852CE5635433911CF10CDB91F52B33639223AD138A41DECA6FEDE1FE90F022100BCA2254366C19A2691C47A00B5B653ABBD44C2F8BAAEF4D2DAF2527CE64549950077005CDC4392FEE6AB4544B15E9AD456E61037FBD5FA47DCA17394B25EE6F6C70ECA00000174E5AC723C0000040300483046022100A5E0906E63E91D4FDDEFFF0352B91E50896007564B448A3828F596DC6B28726D022100FC91EAED02168866054EE18A2E5346C4CC51FEB3FA10A91D2EDBF99125F86CE6'
],
1,
h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
The size of the CBOR encoding (CBOR sequence) is 1332 bytes.
Appendix B. X.509 Certificate Profile, ASN.1
EDITOR'S NOTE: The ASN.1 below is not up to date with the rest of the
specification. The below ASN.1 for RFC 7925 profile should be in
draft-ietf-uta-tls13-iot-profile instead. If CBOR Certificates
support a large subset of RFC 5280, we should probably not duplicate
all the ASN.1 in that document. Should be discussed what kind and
how much (if any) ASN.1 this document needs. If possible, one option
would be to have ASN.1 for the restrictions compared to RFC 5280.
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IOTCertificate DEFINITIONS EXPLICIT TAGS ::= BEGIN
Certificate ::= SEQUENCE {
tbsCertificate TBSCertificate,
signatureAlgorithm AlgorithmIdentifier,
signatureValue BIT STRING
}
TBSCertificate ::= SEQUENCE {
version [0] INTEGER {v3(2)},
serialNumber INTEGER (1..MAX),
signature AlgorithmIdentifier,
issuer Name,
validity Validity,
subject Name,
subjectPublicKeyInfo SubjectPublicKeyInfo,
extensions [3] Extensions OPTIONAL
}
Name ::= SEQUENCE SIZE (1) OF DistinguishedName
DistinguishedName ::= SET SIZE (1) OF CommonName
CommonName ::= SEQUENCE {
type OBJECT IDENTIFIER (id-at-commonName),
value UTF8String
}
Validity ::= SEQUENCE {
notBefore UTCTime,
notAfter UTCTime
}
SubjectPublicKeyInfo ::= SEQUENCE {
algorithm AlgorithmIdentifier,
subjectPublicKey BIT STRING
}
AlgorithmIdentifier ::= SEQUENCE {
algorithm OBJECT IDENTIFIER,
parameters ANY DEFINED BY algorithm OPTIONAL }
}
Extensions ::= SEQUENCE SIZE (1..MAX) OF Extension
Extension ::= SEQUENCE {
extnId OBJECT IDENTIFIER,
critical BOOLEAN DEFAULT FALSE,
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extnValue OCTET STRING
}
id-at-commonName OBJECT IDENTIFIER ::=
{joint-iso-itu-t(2) ds(5) attributeType(4) 3}
END
Acknowledgments
The authors want to thank Henk Birkholz, Carsten Bormann, Russ
Housley, Olle Johansson, Benjamin Kaduk, Ilari Liusvaara, Laurence
Lundblade, Thomas Peterson, Michael Richardson, Stefan Santesson, Jim
Schaad, Fraser Tweedale, and Rene Struik for reviewing and commenting
on intermediate versions of the draft.
Authors' Addresses
Shahid Raza
RISE AB
Email: shahid.raza@ri.se
Joel Hoeglund
RISE AB
Email: joel.hoglund@ri.se
Goeran Selander
Ericsson AB
Email: goran.selander@ericsson.com
John Preuss Mattsson
Ericsson AB
Email: john.mattsson@ericsson.com
Martin Furuhed
Nexus Group
Email: martin.furuhed@nexusgroup.com
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