Draft: draft-ietf-rats-architecture

Commentary: and 
 A few words on the “ why that is the case ” are needed here . 
 Both examples basically seem to be the same here ?
Paragraph (version A):
Confidentiality protection can be realized via physical provisioning
facility security involving no encryption at all.  For low-security
use cases, this might be simply locking doors and limiting personnel
that can enter the facility.  For high-security use cases, this might
involve a special area of the facility accessible only to select
security-trained personnel.
Paragraph (version A):
Typically, cryptography is used to enable confidentiality protection.
This can result in recursive problems, as the key material used to
provision attestation keys must again somehow have been provisioned
securely beforehand (requiring an additional level of protection, and
so on).
Paragraph (version A):
In general, a combination of some physical security measures and some
cryptographic measures is used to establish confidentiality
protection.
Paragraph (version A):
Another way to provision key material is to generate it on the device
and export the validation key.  If public-key cryptography is being
used, then only integrity is necessary.  Confidentiality of public
keys is not necessary.
Paragraph (version A):
In all cases, attestation key provisioning must ensure that only
attestation key material that is generated by a valid Endorser is
established in Attesters.  For many use cases, this will involve
physical security at the facility, to prevent unauthorized devices
from being manufactured that may be counterfeit or incorrectly
configured.
Paragraph (version B):
The degree of protection afforded to this key material can vary by
device, based upon considerations as to a cost/benefit evaluation of
the intended function of the device.  The confidentiality protection
is fundamentally based upon some amount of physical protection: while
encryption is often used to provide confidentiality when a key is
conveyed across a factory, where the attestation key is created or
applied, it must be available in an unencrypted form.  The physical
protection can therefore vary from situations where the key is
unencrypted only within carefully controlled secure enclaves within
silicon, to situations where an entire facility is considered secure,
by the simple means of locked doors and limited access.
Paragraph (version B):
The cryptography that is used to enable confidentiality protection of
the attestation key comes with its own requirements to be secured.
This results in recursive problems, as the key material used to
provision attestation keys must again somehow have been provisioned
securely beforehand (requiring an additional level of protection, and
so on).
Paragraph (version B):
So, this is why, in general, a combination of some physical security
measures and some cryptographic measures is used to establish
confidentiality protection.
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 get a key they control endorsed.
Paragraph (version B):
To summarize: attestation key provisioning must ensure that only
valid attestation key material is established in Attesters.