Draft: draft-ietf-rats-architecture

Commentary: fixes for comments from  . 
 CC Thanks to    for the General Area Review Team ( Gen - ART ) review ( ) . This document uses the RFC2119 keyword [ ' SHOULD ' ] , but does not contain the recommended RFC8174 boilerplate . I do n't think you need to add the boilerplate , simply rephrase the sentence so it is more clear that you are in fact citing RFC4086 here ? Found terminology that should be reviewed for inclusivity ; see for background and more guidance : Terms and ; alternatives might be , , , , All comments below are about very minor potential issues that you may choose to address in some way - or ignore - as you see fit . Some were flagged by automated tools ( via ) , so there will likely be some false positives . There is no need to let me know what you did with these suggestions . Nowadays , it 's more common to write this as one word . Use " an " instead of " a " if the following word starts with a vowel sound , e.g. " an article " , " an hour " . Possible typo : you repeated a word . Do not mix variants of the same word ( " among " and " amongst " ) within a single text . ( Also elsewhere . ) A comma may be missing after the conjunctive / linking adverb " Therefore " . A comma may be missing after the conjunctive / linking adverb " Typically " . Possible typo : you repeated a word . Did you mean " out - of - band " ? The plural noun " messages " can not be used with the article " a " . Did you mean " a conceptual message " or " conceptual messages " ? This word is normally spelled with a hyphen . Possible typo : you repeated a word . This word is normally spelled as one word . Use " an " instead of " a " if the following word starts with a vowel sound , e.g. " an article " , " an hour " . The verb " kept " is used with the gerund form . The preposition " to " is required before the verb " get " . This word is normally spelled with a hyphen . The adverb " forever " is spelled as one word . Possible typo : you repeated a word . A comma may be missing after the conjunctive / linking adverb " Thus " . A comma may be missing after the conjunctive / linking adverb " Similarly " . 
 lgtm , including  's comma
Mailing list commentary: Reviewer : Review result : Ready with Nits I am the assigned Gen - ART reviewer for this draft . The General Area Review Team ( Gen - ART ) reviews all IETF documents being processed by the IESG for the IETF Chair . Please treat these comments just like any other last call comments . For more information , please see the FAQ at . Document : draft - ietf - rats - architecture- ? ? Reviewer : Review Date : 2022 - 08 - 19 IETF LC End Date : 2022 - 09 - 01 IESG Telechat date : Not scheduled for a telechat Summary : This document provides an architectural overview of the entities involved that make such tests possible through the process of generating , conveying , and evaluating evidentiary claims . An attempt is made to provide for a model that is neutral toward processor architectures , the content of claims , and protocols . Major issues : None Minor issues : As this is a architecture specification should this be standards track . Normative language should then be applied where applicable . As the architecture of rats is related to security a lot of what is in the security considerations to me seems part of the architecture and maybe should be moved to the body of the document or appendix . Section 3 describes the environment of an attester . Section 3.2 clearly describes a layered environment , however section 3.3 describes a composite environment using a carrier grade router as an example . I think here the composite should be described just as is done in the layer environment section but not referencing an environment use case that may not be applicable to RAT . So within a carrier grade router chassis the backplane communication is all done vendor proprietary no external elements so I do n’t see how trust comes into play as well as the backplane communication is hardware bus elements for backplane throughput for the LC and then as well router OS software component for the backplane communication . I think maybe choosing a better example that applies to RAT composite environment would be better . Nits / editorial comments : Throughout the document there are acronyms used and the acronyms have not been expanded . Few words like ROM , BIOS , TEEP , TLS , CWT , JWT , X.509 , TPM etc
Paragraph (version A):
A bank back-end system might refuse to transact with another
system that is not known to be in a good state.
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A bank backend system might refuse to transact with another system
that is not known to be in a good state.
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Any web site, mobile application back-end, or service that relies
on authentication data based on biometric information.
Paragraph (version B):
Any web site, mobile application backend, or service that relies
on authentication data based on biometric information.
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The text below summarizes the activities conducted by the roles
illustrated in dataflow.  Roles are assigned to entities.  Entities
are often system components RFC4949, such as devices.  As the term
device is typically more intuitive than the term entity or system
component, device is often used as a illustrative synonym throughout
this document.
Paragraph (version B):
The text below summarizes the activities conducted by the roles
illustrated in dataflow.  Roles are assigned to entities.  Entities
are often system components RFC4949, such as devices.  As the term
device is typically more intuitive than the term entity or system
component, device is often used as an illustrative synonym throughout
this document.
Paragraph (version A):
See messages for further discussion of the conceptual messages shown
in dataflow.  Section terminology provides a more complete definition
of all RATS roles.
Paragraph (version B):
See messages for further discussion of the conceptual messages shown
in dataflow.  terminology provides a more complete definition of all
RATS roles.
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Among these slots, only a "main" slot can communicate with the
Verifier while other slots cannot.  But other slots can communicate
with the main slot by the links between them inside the router.  So
the main slot collects the Evidence of other slots, produces the
final Evidence of the whole router and conveys the final Evidence to
the Verifier.  Therefore the router is a composite device, each slot
is an Attester, and the main slot is the lead Attester.
Paragraph (version B):
Among these slots, only a "main" slot can communicate with the
Verifier while other slots cannot.  But other slots can communicate
with the main slot by the links between them inside the router.  So
the main slot collects the Evidence of other slots, produces the
final Evidence of the whole router and conveys the final Evidence to
the Verifier.  Therefore, the router is a composite device, each slot
is an Attester, and the main slot is the lead Attester.
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Another example is a multi-chassis router composed of multiple single
carrier-grade routers.  Multi-chassis router setups create redundancy
groups that provide higher throughput by interconnecting multiple
routers in these groups, which can be treated as one logical router
for simpler management.  A multi-chassis router setup provides a
management point that connects to the Verifier.  Typically one router
in the group is designated as the main router.  Other routers in the
multi-chassis setup are connected to the main router only via
physical network links and are therefore managed and appraised via
the main router's help.  Consequently, a multi-chassis router setup
is a composite device, each router is an Attester, and the main
router is the lead Attester.
Paragraph (version B):
Another example is a multi-chassis router composed of multiple single
carrier-grade routers.  Multi-chassis router setups create redundancy
groups that provide higher throughput by interconnecting multiple
routers in these groups, which can be treated as one logical router
for simpler management.  A multi-chassis router setup provides a
management point that connects to the Verifier.  Typically, one
router in the group is designated as the main router.  Other routers
in the multi-chassis setup are connected to the main router only via
physical network links and are therefore managed and appraised via
the main router's help.  Consequently, a multi-chassis router setup
is a composite device, each router is an Attester, and the main
router is the lead Attester.
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The passport model is so named because of its resemblance to how
nations issue passports to their citizens.  The nature of the
Evidence that an individual needs to provide to its local authority
is specific to the country involved.  The citizen retains control of
the resulting passport document and presents it to other entities
when it needs to assert a citizenship or identity Claim, such as an
airport immigration desk.  The passport is considered sufficient
because it vouches for the citizenship and identity Claims, and it is
issued by a trusted authority.  Thus, in this immigration desk
analogy, the citizen is the Attester, the passport issuing agency is
a Verifier, the passport application and identifying information
(e.g., birth certificate) is the the Evidence, the passport is an
Attestation Result, and the immigration desk is a Relying Party.
Paragraph (version B):
The passport model is so named because of its resemblance to how
nations issue passports to their citizens.  The nature of the
Evidence that an individual needs to provide to its local authority
is specific to the country involved.  The citizen retains control of
the resulting passport document and presents it to other entities
when it needs to assert a citizenship or identity Claim, such as an
airport immigration desk.  The passport is considered sufficient
because it vouches for the citizenship and identity Claims, and it is
issued by a trusted authority.
Paragraph (version B):
Thus, in this immigration desk analogy, the citizen is the Attester,
the passport issuing agency is a Verifier, and the passport
application and identifying information (e.g., birth certificate) is
the the Evidence.  The passport is an Attestation Result, and the
immigration desk is a Relying Party.
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Thus, trusting a Verifier might be expressed by having the Relying
Party store the Verifier's key or certificate in its trust anchor
store, or might be expressed by storing the public key or certificate
of an entity (e.g., a Certificate Authority) that is in the
Verifier's certificate path.  For example, the Relying Party can
verify that the Verifier is an expected one by out of band
establishment of key material, combined with a protocol like TLS to
communicate.  There is an assumption that between the establishment
of the trusted key material and the creation of the Evidence, that
the Verifier has not been compromised.
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Thus, trusting a Verifier might be expressed by having the Relying
Party store the Verifier's key or certificate in its trust anchor
store, or might be expressed by storing the public key or certificate
of an entity (e.g., a Certificate Authority) that is in the
Verifier's certificate path.  For example, the Relying Party can
verify that the Verifier is an expected one by out-of-band
establishment of key material, combined with a protocol like TLS to
communicate.  There is an assumption that between the establishment
of the trusted key material and the creation of the Evidence, that
the Verifier has not been compromised.
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dataflow illustrates the flow of a conceptual messages between
various roles.  This section provides additional elaboration and
implementation considerations.  It is the responsibility of protocol
specifications to define the actual data format and semantics of any
relevant conceptual messages.
Paragraph (version B):
dataflow illustrates the flow of conceptual messages between various
roles.  This section provides additional elaboration and
implementation considerations.  It is the responsibility of protocol
specifications to define the actual data format and semantics of any
relevant conceptual messages.
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Thus, Attestation Results can contain detailed information about an
Attester, which can include privacy sensitive information as
discussed in section privacy-considerations.  Unlike Evidence, which
is often very device- and vendor-specific, Attestation Results can be
vendor-neutral, if the Verifier has a way to generate vendor-agnostic
information based on the appraisal of vendor-specific information in
Evidence.  This allows a Relying Party's appraisal policy to be
simpler, potentially based on standard ways of expressing the
information, while still allowing interoperability with heterogeneous
devices.
Paragraph (version B):
Thus, Attestation Results can contain detailed information about an
Attester, which can include privacy sensitive information as
discussed in privacy-considerations.  Unlike Evidence, which is often
very device- and vendor-specific, Attestation Results can be vendor-
neutral, if the Verifier has a way to generate vendor-agnostic
information based on the appraisal of vendor-specific information in
Evidence.  This allows a Relying Party's appraisal policy to be
simpler, potentially based on standard ways of expressing the
information, while still allowing interoperability with heterogeneous
devices.
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with a epoch ID that the receiver has not yet obtained.
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with an epoch ID that the receiver has not yet obtained.
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The keys generated in the factory, whether generated in the device or
off-device by the factory SHOULD be generated by a Cryptographically
Strong Sequence (RFC4086, Section 6.2).
Paragraph (version B):
When generating keys off-device in the factory or in the device, the
use of a Cryptographically Strong Sequence (RFC4086, Section 6.2)
needs consideration.
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When key material is generated within a device and the secret part of
it never leaves the device, then the problem may lessen.  For public-
key cryptography, it is, by definition, not necessary to maintain
confidentiality of the public key: however integrity of the chain of
custody of the public key is necessary in order to avoid attacks
where an attacker is able get a key they control endorsed.
Paragraph (version B):
When key material is generated within a device and the secret part of
it never leaves the device, then the problem may lessen.  For public-
key cryptography, it is, by definition, not necessary to maintain
confidentiality of the public key: however integrity of the chain of
custody of the public key is necessary in order to avoid attacks
where an attacker is able to get a key they control endorsed.
Paragraph (version A):
An attacker who is able to tamper with epoch IDs can potentially lock
all the participants in a certain epoch of choice for ever,
effectively freezing time.  This is problematic since it destroys the
ability to ascertain freshness of Evidence and Attestation Results.
Paragraph (version B):
An attacker who is able to tamper with epoch IDs can potentially lock
all the participants in a certain epoch of choice forever,
effectively freezing time.  This is problematic since it destroys the
ability to ascertain freshness of Evidence and Attestation Results.