Draft: draft-ietf-rats-architecture

Commentary: Edited Privacy and Security considerations sections per Issue 45
Paragraph (version A):
It is important to prevent replay attacks where an attacker replays
old Evidence or an old Attestation Result that is no longer correct.
To do so, some mechanism of ensuring that the Evidence and
Attestation Result are fresh, meaning that there is some degree of
assurance that they still reflect the latest state of the Attester,
and that any Attestation Result was generated using the latest
Appraisal Policy for Evidence.  There is, however, always a race
condition possible in that the state of the Attester, and the
Appraisal Policy for Evidence, may change immediately after the
Evidence or Attestation Result was generated.  The goal is merely to
narrow the time window to something the Verifier (for Evidence) or
Relying Party (for an Attestation Result) is willing to accept.
Paragraph (version B):
It is important to prevent replay attacks where an attacker replays
old Evidence or an old Attestation Result that is no longer correct.
To do so, some mechanism of ensuring that the Evidence and
Attestation Result are fresh, meaning that there is some degree of
assurance that they still reflect the latest state of the Attester,
and that any Attestation Result was generated using the latest
Appraisal Policy for Evidence.  There is, however, always a race
condition possible in that the state of the Attester, and the
Appraisal Policy for Evidence, might change immediately after the
Evidence or Attestation Result was generated.  The goal is merely to
narrow the time window to something the Verifier (for Evidence) or
Relying Party (for an Attestation Result) is willing to accept.
Paragraph (version A):
The conveyance of Evidence and the resulting Attestation Results
reveal a great deal of information about the internal state of a
device.  In many cases, the whole point of the Attestation process is
to provide reliable information about the type of the device and the
firmware/software that the device is running.  This information is
particularly interesting to many attackers.  For example, knowing
that a device is running a weak version of firmware provides a way to
aim attacks better.
Paragraph (version A):
Protocols that convey Evidence or Attestation Results are responsible
for detailing what kinds of information are disclosed, and to whom
they are exposed.
Paragraph (version A):
Any solution that conveys information used for security purposes,
whether such information is in the form of Evidence, Attestation
Results, or Endorsements, or Appraisal Policy, needs to support end-
to-end integrity protection and replay attack prevention, and often
also needs to support additional security protections.  For example,
additional means of authentication, confidentiality, integrity,
replay, denial of service and privacy protection are needed in many
use cases.  freshness discusses ways in which freshness can be used
in this architecture to protect against replay attacks.
Paragraph (version B):
The conveyance of Evidence and the resulting Attestation Results
reveal a great deal of information about the internal state of a
device.  In many cases, the whole point of the Attestation process is
to provide reliable information about the type of the device and the
firmware/software that the device is running.  This information might
be particularly interesting to many attackers.  For example, knowing
that a device is running a weak version of firmware provides a way to
aim attacks better.
Paragraph (version B):
Evidence and Attestation Results data structures are expected to
support integrity protection encoding (e.g., COSE, JOSE, X.509) and
optionally might support confidentiality protection (e.g., COSE,
JOSE).  Therefore, if confidentiality protection is omitted or
unavailable, the protocols that convey Evidence or Attestation
Results are responsible for detailing what kinds of information are
disclosed, and to whom they are exposed.
Paragraph (version B):
Any solution that conveys information used for security purposes,
whether such information is in the form of Evidence, Attestation
Results, Endorsements, or Appraisal Policy, needs to support end-to-
end integrity protection and replay attack prevention, and often also
needs to support additional security protections.  For example,
additional means of authentication, confidentiality, integrity,
replay, denial of service and privacy protection are needed in many
use cases.  freshness discusses ways in which freshness can be used
in this architecture to protect against replay attacks.
Paragraph (version B):
The security of conveyed information may be applied at different
layers, whether by a conveyance protocol, or an information encoding
format.  This architecture expects attestation messages (i.e.,
Evidence, Attestation Results, Endorsements and Policies) are end-to-
end protected based on the role interaction context.  For example, if
an Attester produces Evidence that is relayed through some other
entity that doesn't implement the Attester or the intended Verifier
roles, then the relaying entity should not expect to have access to
the Evidence.