draft-ietf-lamps-hash-of-root-key-cert-extn-05.txt   draft-ietf-lamps-hash-of-root-key-cert-extn-06.txt 
Network Working Group R. Housley Network Working Group R. Housley
Internet-Draft Vigil Security Internet-Draft Vigil Security
Intended status: Informational January 31, 2019 Intended status: Informational June 28, 2019
Expires: August 4, 2019 Expires: December 30, 2019
Hash Of Root Key Certificate Extension Hash Of Root Key Certificate Extension
draft-ietf-lamps-hash-of-root-key-cert-extn-05 draft-ietf-lamps-hash-of-root-key-cert-extn-06
Abstract Abstract
This document specifies the Hash Of Root Key certificate extension. This document specifies the Hash Of Root Key certificate extension.
This certificate extension is carried in the self-signed certificate This certificate extension is carried in the self-signed certificate
for a trust anchor, which is often called a Root Certification for a trust anchor, which is often called a Root Certification
Authority (CA) certificate. This certificate extension unambiguously Authority (CA) certificate. This certificate extension unambiguously
identifies the next public key that will be used at some point in the identifies the next public key that will be used at some point in the
future as the next Root CA certificate, eventually replacing the future as the next Root CA certificate, eventually replacing the
current one. current one.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 4, 2019. This Internet-Draft will expire on December 30, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2
1.2. ASN.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. ASN.1 . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Hash Of Root Key Certificate Extension . . . . . . . . . . . 4 3. Hash Of Root Key Certificate Extension . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
5. Operational Considerations . . . . . . . . . . . . . . . . . 4 5. Operational Considerations . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7 8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 8 8.2. Informative References . . . . . . . . . . . . . . . . . 9
Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 8 Appendix A. ASN.1 Module . . . . . . . . . . . . . . . . . . . . 9
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 10 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
This document specifies the Hash Of Root Key X.509 version 3 This document specifies the Hash Of Root Key X.509 version 3
certificate extension. The extension is an optional addition to the certificate extension. The extension is an optional addition to the
Internet X.509 Public Key Infrastructure Certificate and Certificate Internet X.509 Public Key Infrastructure Certificate and Certificate
Revocation List (CRL) Profile [RFC5280]. The certificate extension Revocation List (CRL) Profile [RFC5280]. The certificate extension
facilitates the orderly transition from one Root Certification facilitates the orderly transition from one Root Certification
Authority (CA) public key to the next. It does so by publishing the Authority (CA) public key to the next. It does so by publishing the
hash value of the next generation public key in the current self- hash value of the next generation public key in the current self-
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1.1. Terminology 1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119][RFC8174] when, and only when, they appear in all BCP 14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
1.2. ASN.1 1.2. ASN.1
Certificates [RFC5280] are generated using ASN.1 [X680]; certificates Certificates [RFC5280] use ASN.1 [X680]; Distinguished Encoding Rules
are always encoded with the Distinguished Encoding Rules (DER) (DER) [X690] are REQUIRED for certificate signing and validation.
[X690].
2. Overview 2. Overview
Before the initial deployment of the Root CA, the following are Before the initial deployment of the Root CA, the following are
generated: generated:
R1 = The initial Root key pair R1 = The initial Root key pair
R2 = The second generation Root key pair R2 = The second generation Root key pair
H2 = Thumbprint (hash) of the public key of R2 H2 = Thumbprint (hash) of the public key of R2
C1 = Self-signed certificate for R1, which also contains H2 C1 = Self-signed certificate for R1, which also contains H2
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The following ASN.1 [X680][X690] syntax defines the HashOfRootKey The following ASN.1 [X680][X690] syntax defines the HashOfRootKey
certificate extension: certificate extension:
ext-HashOfRootKey EXTENSION ::= { -- Only in Root CA certificates ext-HashOfRootKey EXTENSION ::= { -- Only in Root CA certificates
SYNTAX HashedRootKey SYNTAX HashedRootKey
IDENTIFIED BY id-ce-hashOfRootKey IDENTIFIED BY id-ce-hashOfRootKey
CRITICALITY {FALSE} } CRITICALITY {FALSE} }
HashedRootKey ::= SEQUENCE { HashedRootKey ::= SEQUENCE {
hashAlg AlgorithmIdentifier, -- Hash algorithm used hashAlg HashAlgorithm, -- Hash algorithm used
hashValue OCTET STRING } -- Hash of DER-encoded hashValue OCTET STRING } -- Hash of DER-encoded
-- SubjectPublicKeyInfo -- SubjectPublicKeyInfo
id-ce-hashOfRootKey ::= OBJECT IDENTIFIER { 1 3 6 1 4 1 51483 2 1 } id-ce-hashOfRootKey ::= OBJECT IDENTIFIER { 1 3 6 1 4 1 51483 2 1 }
The definitions of EXTENSION and HashAlgorithm can be found in The definitions of EXTENSION and HashAlgorithm can be found in
[RFC5912]. [RFC5912].
The hashAlg indicates the one-way hash algorithm that was used to The hashAlg indicates the one-way hash algorithm that was used to
compute the hash value. compute the hash value.
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available in Section 4.4 of [RFC4210]. In particular, the oldWithNew available in Section 4.4 of [RFC4210]. In particular, the oldWithNew
and newWithOld advice ensures that relying parties are able to and newWithOld advice ensures that relying parties are able to
validate certificates issued under the current Root CA certificate validate certificates issued under the current Root CA certificate
and the next generation Root CA certificate throughout the and the next generation Root CA certificate throughout the
transition. The notAfter field in the oldWithNew certificate MUST transition. The notAfter field in the oldWithNew certificate MUST
cover the validity period of all unexpired certificates issued under cover the validity period of all unexpired certificates issued under
the old Root CA private key. Further, this advice SHOULD be followed the old Root CA private key. Further, this advice SHOULD be followed
by Root CAs to avoid the need for all relying parties to make the by Root CAs to avoid the need for all relying parties to make the
transition at the same time. transition at the same time.
After issuing the oldWithNew and newWithOld certificates, the Root CA After issuing the newWithOld certificate, the Root CA MUST stop using
MUST stop using the old private key to sign certificates. the old private key to sign certificates.
Some enterprise and application-specific environments offer a Some enterprise and application-specific environments offer a
directory service or certificate repository to make certificate and directory service or certificate repository to make certificate and
CRLs available to relying parties. Section 3 in [RFC5280] describes CRLs available to relying parties. Section 3 in [RFC5280] describes
a certificate repository. When a certificate repository is a certificate repository. When a certificate repository is
available, the oldWithNew and newWithOld certificates SHOULD be available, the oldWithNew and newWithOld certificates SHOULD be
published before the successor to the current Root CA self-signed published before the successor to the current Root CA self-signed
certificate is released. Recipients that are able to obtain the certificate is released. Recipients that are able to obtain the
oldWithNew certificate SHOULD immediately remove the old Root CA oldWithNew certificate SHOULD immediately remove the old Root CA
self-signed certificate from the trust anchor store. self-signed certificate from the trust anchor store.
In environments without such a directory service or repository, like
the Web PKI, recipients need a way to obtain the oldWithNew and
newWithOld certificates. The Root CA SHOULD include the subject
information access extension [RFC5280] with the accessMethod set to
id-ad-caRepository and the assessLocation set to the HTTP URL that
can be used to fetch a DER-encoded "certs-only" (simple PKI response)
message as specified in [RFC5272] in all of their self-signed
certificates. The Root CA SHOULD publish the "certs-only" message
with the oldWithNew certificate and the newWithOld certificate before
the subsequent Root CA self-signed certificate is released. The
"certs-only" message format allows certificates to be added and
removed from the bag of certificates over time, so the same HTTP URL
can be used throughout the lifetime of the Root CA.
In environments without such a directory service or repository, In environments without such a directory service or repository,
recipients SHOULD keep both the old and replacement Root CA self- recipients SHOULD keep both the old and replacement Root CA self-
signed certificate in the trust anchor store for some amount of time signed certificates in the trust anchor store for some amount of time
to ensure that all end-entity certificates can be validated until to ensure that all end-entity certificates can be validated until
they expire. The recipient MAY keep the old Root CA self-signed they expire. The recipient MAY keep the old Root CA self-signed
certificate until all of the certificates in the local cache that are certificate until all of the certificates in the local cache that are
subordinate to it have expired. subordinate to it have expired.
Certification path construction is more complex when multiple self- Certification path construction is more complex when the trust anchor
signed certificates in the trust anchor store have the same store contains multiple self-signed certificates with the same
distinguished name. For this reason, the replacement Root CA self- distinguished name. For this reason, the replacement Root CA self-
signed certificate SHOULD contain a different distinguished name than signed certificate SHOULD contain a different distinguished name than
the one it is replacing. One approach is to include a number as part the one it is replacing. One approach is to include a number as part
of the name that is incremented with each generation, such as of the name that is incremented with each generation, such as
"Example CA", "Example CA G2", "Example CA G3", and so on. "Example CA", "Example CA G2", "Example CA G3", and so on.
Changing names from one generation to another can lead to confusion Changing names from one generation to another can lead to confusion
when reviewing the history of a trust anchor store. To assist with when reviewing the history of a trust anchor store. To assist with
such review, a recipient MAY create an audit entry to capture the old such review, a recipient MAY create an audit entry to capture the old
and replacement self-signed certificates. and replacement self-signed certificates.
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preimage attacks [RFC4270]. A first-preimage attack against the hash preimage attacks [RFC4270]. A first-preimage attack against the hash
function would allow an attacker to find another input that results function would allow an attacker to find another input that results
published hash value. For the attack to be successful, the input published hash value. For the attack to be successful, the input
would have to be a valid SubjectPublicKeyInfo that contains a public would have to be a valid SubjectPublicKeyInfo that contains a public
key that corresponds to a private key known to the attacker. A key that corresponds to a private key known to the attacker. A
second-preimage attack becomes possible once the Root CA releases the second-preimage attack becomes possible once the Root CA releases the
next generation public key, which makes the input to the hash next generation public key, which makes the input to the hash
function available to the attacker and everyone else. Again, the function available to the attacker and everyone else. Again, the
attacker needs to find a valid SubjectPublicKeyInfo that contains the attacker needs to find a valid SubjectPublicKeyInfo that contains the
public key that corresponds to a private key known to the attacker. public key that corresponds to a private key known to the attacker.
If the employed hash function is broken after the Root CA publishes
the self-signed certificate with the HashOfRootKey certificate
extension, an attacker would be able to trick the recipient into
installing the incorrect next generation certificate in the trust
anchor store.
If an early release of the next generation public key occurs and the If an early release of the next generation public key occurs and the
Root CA is concerned that attackers were given too much lead time to Root CA is concerned that attackers were given too much lead time to
analyze that public key, then the Root CA can transition to a freshly analyze that public key, then the Root CA can transition to a freshly
generated key pair by rapidly performing two transitions. The first generated key pair by rapidly performing two transitions. The first
transition takes the Root CA to the key pair that suffered the early transition takes the Root CA to the key pair that suffered the early
release, and it causes the Root CA to generate the subsequent Root release, and it causes the Root CA to generate the subsequent Root
key pair. The second transition occurs when the Root CA is confident key pair. The second transition occurs when the Root CA is confident
that the population of relying parties have completed the first that the population of relying parties have completed the first
transition, and it takes the Root CA to the freshly generated key transition, and it takes the Root CA to the freshly generated key
pair. Of course, the second transition also causes the Root CA to pair. Of course, the second transition also causes the Root CA to
generate another key pair that is reserved for future use. generate another key pair that is reserved for future use. Queries
for the CRLs associated with certificates that are subordinate to the
self-signed certificate can give some indication for the number of
relying parties that are still actively using the self-signed
certificates.
7. Acknowledgements 7. Acknowledgements
The Secure Electronic Transaction (SET) [SET] specification published The Secure Electronic Transaction (SET) [SET] specification published
by MasterCard and VISA in 1997 includes a very similar certificate by MasterCard and VISA in 1997 includes a very similar certificate
extension. The SET certificate extension has essentially the same extension. The SET certificate extension has essentially the same
semantics, but the syntax fairly different. semantics, but the syntax fairly different.
CTIA - The Wireless Association is developing a public key CTIA - The Wireless Association - is developing a public key
infrastructure that will make use of the certificate extension infrastructure that will make use of the certificate extension
described in this document. described in this document, and the object identifiers used in the
ASN.1 module were assigned by CTIA.
Many thanks to Stefan Santesson, Jim Schaad, Daniel Kahn Gillmor, Many thanks to Stefan Santesson, Jim Schaad, Daniel Kahn Gillmor,
Joel Halpern, Paul Hoffman, and Rich Salz. Their review and comments Joel Halpern, Paul Hoffman, Rich Salz, and Ben Kaduk. Their review
have greatly improved the document, especially the Operational and comments have greatly improved the document, especially the
Considerations and Security Considerations sections. Operational Considerations and Security Considerations sections.
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4210] Adams, C., Farrell, S., Kause, T., and T. Mononen, [RFC4210] Adams, C., Farrell, S., Kause, T., and T. Mononen,
"Internet X.509 Public Key Infrastructure Certificate "Internet X.509 Public Key Infrastructure Certificate
Management Protocol (CMP)", RFC 4210, Management Protocol (CMP)", RFC 4210,
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"Internet X.509 Public Key Infrastructure Certificate "Internet X.509 Public Key Infrastructure Certificate
Management Protocol (CMP)", RFC 4210, Management Protocol (CMP)", RFC 4210,
DOI 10.17487/RFC4210, September 2005, DOI 10.17487/RFC4210, September 2005,
<https://www.rfc-editor.org/info/rfc4210>. <https://www.rfc-editor.org/info/rfc4210>.
[RFC4270] Hoffman, P. and B. Schneier, "Attacks on Cryptographic [RFC4270] Hoffman, P. and B. Schneier, "Attacks on Cryptographic
Hashes in Internet Protocols", RFC 4270, Hashes in Internet Protocols", RFC 4270,
DOI 10.17487/RFC4270, November 2005, DOI 10.17487/RFC4270, November 2005,
<https://www.rfc-editor.org/info/rfc4270>. <https://www.rfc-editor.org/info/rfc4270>.
[RFC5272] Schaad, J. and M. Myers, "Certificate Management over CMS
(CMC)", RFC 5272, DOI 10.17487/RFC5272, June 2008,
<https://www.rfc-editor.org/info/rfc5272>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<https://www.rfc-editor.org/info/rfc5280>. <https://www.rfc-editor.org/info/rfc5280>.
[RFC5912] Hoffman, P. and J. Schaad, "New ASN.1 Modules for the [RFC5912] Hoffman, P. and J. Schaad, "New ASN.1 Modules for the
Public Key Infrastructure Using X.509 (PKIX)", RFC 5912, Public Key Infrastructure Using X.509 (PKIX)", RFC 5912,
DOI 10.17487/RFC5912, June 2010, DOI 10.17487/RFC5912, June 2010,
<https://www.rfc-editor.org/info/rfc5912>. <https://www.rfc-editor.org/info/rfc5912>.
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HashedRootKeyCertExtn { 1 3 6 1 4 1 51483 0 1 } HashedRootKeyCertExtn { 1 3 6 1 4 1 51483 0 1 }
DEFINITIONS IMPLICIT TAGS ::= DEFINITIONS IMPLICIT TAGS ::=
BEGIN BEGIN
-- EXPORTS All -- EXPORTS All
IMPORTS IMPORTS
AlgorithmIdentifier{}, DIGEST-ALGORITHM HashAlgorithm
FROM AlgorithmInformation-2009 -- [RFC5912] FROM PKIX1-PSS-OAEP-Algorithms-2009 -- [RFC5912]
{ iso(1) identified-organization(3) dod(6) internet(1) { iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0) security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-algorithmInformation-02(58) } id-mod-pkix1-rsa-pkalgs-02(54) }
EXTENSION EXTENSION
FROM PKIX-CommonTypes-2009 FROM PKIX-CommonTypes-2009
{ iso(1) identified-organization(3) dod(6) internet(1) { iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0) security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-pkixCommon-02(57) } ; id-mod-pkixCommon-02(57) } ;
-- --
-- Expand the certificate extensions list in [RFC5912] -- Expand the certificate extensions list in [RFC5912]
-- --
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-- --
-- HashOfRootKey Certificate Extension -- HashOfRootKey Certificate Extension
-- --
ext-HashOfRootKey EXTENSION ::= { -- Only in Root CA certificates ext-HashOfRootKey EXTENSION ::= { -- Only in Root CA certificates
SYNTAX HashedRootKey SYNTAX HashedRootKey
IDENTIFIED BY id-ce-hashOfRootKey IDENTIFIED BY id-ce-hashOfRootKey
CRITICALITY {FALSE} } CRITICALITY {FALSE} }
HashedRootKey ::= SEQUENCE { HashedRootKey ::= SEQUENCE {
hashAlg HashAlgorithmId, -- Hash algorithm used hashAlg HashAlgorithm, -- Hash algorithm used
hashValue OCTET STRING } -- Hash of DER-encoded hashValue OCTET STRING } -- Hash of DER-encoded
-- SubjectPublicKeyInfo -- SubjectPublicKeyInfo
HashAlgorithmId ::= AlgorithmIdentifier {DIGEST-ALGORITHM,{ ... }} HashAlgorithmId ::= AlgorithmIdentifier {DIGEST-ALGORITHM,{ ... }}
id-ce-hashOfRootKey OBJECT IDENTIFIER ::= { 1 3 6 1 4 1 51483 2 1 } id-ce-hashOfRootKey OBJECT IDENTIFIER ::= { 1 3 6 1 4 1 51483 2 1 }
END END
Author's Address Author's Address
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