Merge pull request #4 from EntrustCorporation/hannestschofenig-patch-1

Adding Use Cases

draft-ounsworth-rats-pkix-evidence.md

@@ -142,8 +142,7 @@ have been using ASN.1-based encodings for a long time prefer the use of
 the same format throughout their software ecosystem. For those use cases
 this specification has been developed.
 
-This specification re-uses the claims defined in {{I-D.ietf-rats-eat}},
-and encodes them as an extension in an X.509 certificate {{RFC5280}}.
+This specification re-uses the claims defined in {{I-D.ietf-rats-eat}}.
 While the encoding of the claims is different to what is defined in
 {{I-D.ietf-rats-eat}}, the semantics of the claims is retained. This
 specification is not an EAP profile, as defined in Section 6 of
@@ -154,8 +153,18 @@ CA Browser Forum to convey properties about hardware security models, such
 as non-exportability, which must be enabled for storing publicly-trusted
 code-signing keys. Hence, this specification is supposed to be used with
 the attestation extension for Certificate Signing Requests (CSRs), see
-{{I-D.ietf-lamps-csr-attestation}}, but Evidence encoded as X.509 certificates
-may also be used in other context.
+{{I-D.ietf-lamps-csr-attestation}}. 
+
+There are, however, other use cases where remote attestation may also be
+used, such as
+
+-  A Certification Authority receives a certificate signing request and wishes to verify that the subject public key was generated in an HSM (for example to satisfy CA/B Forum subscriber private key verification requirement). They may also wish to verify that the operations the HSM will allow for the corresponding private key are consistent with the purpose of the requested certificate.
+
+- A user of a Cloud Service Provider's 'Bring Your Own Key' service wishes to transfer their locally-generated key securely to the CSP's service by encrypting it under the CSP's public key. As part of their due diligence on the CSP's key they wish to verify (1) that it was generated by an HSM and (2) may only be used to unwrap the key into an HSM (i.e. unwrap permission but not decrypt permission).
+
+- An auditor of an identity provision service (or a competent end user) may wish to verify that keys representing end-user identities are held in an HSM and have permissions that are in line with the applicable regulations. For example, they may wish verify that the protection arrangements for assigned keys cannot be changed.
+
+- A manufacturer needs to provision configuration info, software, and credentials to a device from remote. With the help of remote attestation the manufacturer is provided enough information to verify that information is only sent to devices it has built.
 
 # Conventions and Definitions