Define Public Key Credential Source and Credential ID.

index.bs

@@ -274,7 +274,7 @@ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "S
 : <dfn>Attestation</dfn>
 :: Generally, <em>attestation</em> is a statement serving to bear witness, confirm, or authenticate.
     In the WebAuthn context, [=attestation=] is employed to <em>attest</em> to the <em>provenance</em> of an [=authenticator=]
-    and the data it emits; including, for example: credential IDs, [=credential key pairs=], signature counters, etc. An
+    and the data it emits; including, for example: [=credential IDs=], [=credential key pairs=], signature counters, etc. An
     [=attestation statement=] is conveyed in an [=attestation object=] during [=registration=]. See also [[#sctn-attestation]]
     and [Figure 3](#fig-attStructs).
 
@@ -297,6 +297,9 @@ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "S
 :: The cryptographically signed {{AuthenticatorAssertionResponse}} object returned by an [=authenticator=] as the result of a
     [=authenticatorGetAssertion=] operation.
 
+    This corresponds to the [[CREDENTIAL-MANAGEMENT-1]] specification's single-use <a
+    spec="credential-management">credentials</a>.
+
 : <dfn>Authenticator</dfn>
 :: A cryptographic entity used by a [=[WAC]=] to (i) generate a [=public key credential=] and register it with a [=[RP]=],
     and (ii) [=authentication|authenticate=] by potentially [=user verification|verifying the user=], and then 
@@ -339,13 +342,70 @@ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "S
 :: A user agent implementing, in conjunction with the underlying platform, the [=Web Authentication API=] and algorithms
     given in this specification, and handling communication between [=authenticators=] and [=[RPS]=].
 
+: <dfn>Credential ID</dfn>
+:: A probabilistically-unique [=byte sequence=] identifying a [=public key credential source=] and its [=authentication assertions=].
+
+    Credential IDs are generated by [=authenticators=] in two forms:
+    1. At least 16 bytes that include at least 100 bits of entropy, or
+    1. The [=public key credential source=], without its [=Credential ID=], encrypted so only its [=managing authenticator=] can
+        decrypt it. This form allows the [=authenticator=] to be nearly stateless, by having the [=[RP]=] store any necessary
+        state.
+
+        Note: [[FIDO-UAF-AUTHNR-CMDS]] includes guidance on encryption techniques under "Security Guidelines".
+
+    [=[RPS]=] do not need to distinguish these two [=Credential ID=] forms.
+
 : <dfn>Credential Public Key</dfn>
 :: The public key portion of an [=[RP]=]-specific <dfn>credential key pair</dfn>, generated by an [=authenticator=] and
     returned to an [=[RP]=] at [=registration=] time (see also [=public key credential=]). The private key portion of the
     [=credential key pair=] is known as the <dfn>credential private key</dfn>. Note that in the case of [=self
     attestation=], the [=credential key pair=] is also used as the [=attestation key pair=], see [=self attestation=]
     for details.
 
+: <dfn>Public Key Credential Source</dfn>
+:: A [=credential source=] ([[CREDENTIAL-MANAGEMENT-1]]) used by an [=authenticator=] to generate [=authentication assertions=]. A public key credential source has:
+
+    * A [=Credential ID=].
+    * A [=credential private key=].
+    * The [=Relying Party Identifier=] for the [=[RP]=] that created this credential source.
+    * An optional [=user handle=] for the person who created this credential source.
+    * Optional other information used by the authenticator to inform its UI. For example, this might include the user's
+        {{displayName}}.
+
+    The [=authenticatorMakeCredential=] operation creates a [=public key credential source=] bound to a <dfn for="public key
+    credential source">managing authenticator</dfn> and returns the [=credential public key=] associated with its [=credential
+    private key=]. The [=[RP]=] can use this [=credential public key=] to verify the [=authentication assertions=] created by
+    this [=public key credential source=].
+
+: <dfn>Public Key Credential</dfn>
+
+:: Generically, a *credential* is data one entity presents to another in order to *authenticate* the former to the latter
+    [[RFC4949]]. The term [=public key credential=] refers to one of: a [=public key credential source=], the
+    possibly-[=attestation|attested=] [=credential public key=] corresponding to a [=public key credential source=], or an
+    [=authentication assertion=]. Which one is generally determined by context.
+
+    <div class="note">
+        Note: This is a [=willful violation=] of [[RFC4949]]. In English, a "credential" is both a) the thing presented to prove
+        a statement and b) intended to be used multiple times. It's impossible to achieve both criteria securely with a single
+        piece of data in a public key system. [[RFC4949]] chooses to define a credential as the thing that can be used multiple
+        times (the public key), while this specification gives "credential" the English term's flexibility. This specification
+        uses more specific terms to identify the data related to an [[RFC4949]] credential:
+
+        : "Authentication information" (possibly including a private key)
+        :: [=Public key credential source=]
+        : "Signed value"
+        :: [=Authentication assertion=]
+        : [[RFC4949]] "credential"
+        :: [=Credential public key=] or [=attestation object=]
+    </div>
+
+    At [=registration=] time, the [=authenticator=] creates an asymmetric key pair, and stores its [=credential private
+    key|private key portion=] and information from the [=[RP]=] into a [=public key credential source=]. The [=credential public
+    key|public key portion=] is returned to the [=[RP]=], who then stores it in conjunction with the present user's account.
+    Subsequently, only that [=[RP]=], as identified by its [=RP ID=], is able to employ the [=public key credential=] in
+    [=authentication|authentication ceremonies=], via the {{CredentialsContainer/get()}} method. The [=[RP]=] uses its stored
+    copy of the [=credential public key=] to verify the resultant [=authentication assertion=].
+
 : <dfn>Rate Limiting</dfn>
 :: The process (also known as throttling) by which an authenticator implements controls against brute force attacks by limiting
     the number of consecutive failed authentication attempts within a given period of time. If the limit is reached, the
@@ -388,17 +448,6 @@ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "S
         [=document.domain=]'s setter provides.
     </div>
 
-: <dfn>Public Key Credential</dfn>
-:: Generically, a <em>credential</em> is data one entity presents to another in order to <em>authenticate</em> the former to the
-    latter [[RFC4949]]. A WebAuthn <em>[=public key credential=]</em> is a <code>{ identifier, type }</code> pair identifying
-    authentication information established by the [=authenticator=] and the [=[RP]=], together, at [=registration=] time. The
-    authentication information consists of an asymmetric key pair, where the [=credential public key|public key portion=] is
-    returned to the [=[RP]=], who then stores it in conjunction with the present user's account. The [=authenticator=] maps the
-    [=credential private key|private key portion=] to the [=[RP]=]'s [=RP ID=] and stores it. Subsequently, only that [=[RP]=],
-    as identified by its [=RP ID=], is able to employ the [=public key credential=] in [=authentication|authentication
-    ceremonies=], via the {{CredentialsContainer/get()}} method. The [=[RP]=] uses its stored copy of the [=credential public
-    key=] to verify the resultant [=authentication assertion=].
-
 : <dfn>Test of User Presence</dfn>
 :: A [=test of user presence=] is a simple form of [=authorization gesture=] and technical process where a user interacts with
     an [=authenticator=] by (typically) simply touching it (other modalities may also exist), yielding a boolean result. Note
@@ -1001,7 +1050,7 @@ method is invoked, the user agent MUST:
                     ::  Create a new {{ArrayBuffer}}, using |global|'s [=%ArrayBuffer%=].
                             If |savedCredentialId| exists, set the value of the new {{ArrayBuffer}} to be the bytes of
                             |savedCredentialId|. Otherwise, set the value of the new {{ArrayBuffer}} to be the bytes of the
-                            credential ID returned from the successful [=authenticatorGetAssertion=] operation, as defined in
+                            [=credential ID=] returned from the successful [=authenticatorGetAssertion=] operation, as defined in
                             [[#op-get-assertion]].
 
                     :   {{PublicKeyCredential/response}}
@@ -1130,7 +1179,7 @@ during registration.
     :   <dfn>attestationObject</dfn>
     ::  This attribute contains an [=attestation object=], which is opaque to, and cryptographically protected against
         tampering by, the client. The [=attestation object=] contains both [=authenticator data=] and an [=attestation
-        statement=]. The former contains the AAGUID, a unique credential ID, and the [=credential public key=]. The
+        statement=]. The former contains the AAGUID, a unique [=credential ID=], and the [=credential public key=]. The
         contents of the [=attestation statement=] are determined by the [=attestation statement format=] used by the
         [=authenticator=]. It also contains any additional information that the [=[RP]=]'s server requires to validate the
         [=attestation statement=], as well as to decode and validate the [=authenticator data=] along with the
@@ -1900,10 +1949,10 @@ When this method is invoked, the [=authenticator=] must perform the following pr
     terminate the operation.
 
 1. Return to the user agent:
-    - |selectedCredential|'s credential ID, if either a list of credentials of length 2 or greater was supplied by the client,
+    - |selectedCredential|'s [=credential ID=], if either a list of credentials of length 2 or greater was supplied by the client,
         or no such list was supplied.
 
-        Note: If the client supplies a list of exactly one credential and it was successfully employed, then its credential ID
+        Note: If the client supplies a list of exactly one credential and it was successfully employed, then its [=credential ID=]
             is not returned since the client already knows it.
 
     - |authenticatorData|
@@ -2009,7 +2058,7 @@ object=] for a given credential. It has the following format:
     <tr>
         <td><dfn>credentialId</dfn></td>
         <td>L</td>
-        <td>Credential ID</td>
+        <td>[=Credential ID=]</td>
     </tr>
     <tr>
         <td><dfn>credentialPublicKey</dfn></td>
@@ -2260,7 +2309,7 @@ When registering a new credential, represented by a {{AuthenticatorAttestationRe
 14. If the attestation statement |attStmt| successfully verified but is not trustworthy per step 12 above, the [=[RP]=] SHOULD fail
     the registration ceremony.
 
-    NOTE: However, if permitted by policy, the [=[RP]=] MAY register the credential ID and credential public key but treat the
+    NOTE: However, if permitted by policy, the [=[RP]=] MAY register the [=credential ID=] and credential public key but treat the
         credential as one with [=self attestation=] (see [[#sctn-attestation-types]]). If doing so, the [=[RP]=] is asserting there
         is no cryptographic proof that the [=public key credential=] has been generated by a particular [=authenticator=] model.
         See [[FIDOSecRef]] and [[UAFProtocol]] for a more detailed discussion.
@@ -2787,7 +2836,7 @@ This attestation statement format is used with FIDO U2F authenticators using the
 
     Generate a Registration Response Message as specified in [[FIDO-U2F-Message-Formats]] section 4.3, with the application parameter set to the
     SHA-256 hash of the [=RP ID=] associated with the given credential, the challenge parameter set to |tbsHash|, and the key handle
-    parameter set to the credential ID of the given credential. Set the raw signature part of this Registration Response Message (i.e., without the user public key,
+    parameter set to the [=credential ID=] of the given credential. Set the raw signature part of this Registration Response Message (i.e., without the user public key,
     key handle, and attestation certificates) as |sig| and set the attestation certificates of
     the attestation public key as |x5c|.
 
@@ -3569,7 +3618,7 @@ In this flow, the [=[RP]=] does not have a preference for [=platform authenticat
         such as attestation regarding the provenance and characteristics of the authenticator.
     - The server stores the [=credential public key=] in its database and associates it with the user as well as with the
         characteristics of authentication indicated by attestation, also storing a friendly name for later use.
-    - The script may store data such as the credential ID in local storage, to improve future UX by narrowing the choice of
+    - The script may store data such as the [=credential ID=] in local storage, to improve future UX by narrowing the choice of
         credential for the user.
 
 The sample code for generating and registering a new key follows:
@@ -3692,10 +3741,10 @@ credential.
 
 9. If an assertion was successfully generated and returned,
     - The script sends the assertion to the server.
-    - The server examines the assertion, extracts the credential ID, looks up the registered
+    - The server examines the assertion, extracts the [=credential ID=], looks up the registered
         credential public key it is database, and verifies the assertion's authentication signature.
-        If valid, it looks up the identity associated with the assertion's credential ID; that
-        identity is now authenticated. If the credential ID is not recognized by the server (e.g.,
+        If valid, it looks up the identity associated with the assertion's [=credential ID=]; that
+        identity is now authenticated. If the [=credential ID=] is not recognized by the server (e.g.,
         it has been deregistered due to inactivity) then the authentication has failed; each [=[RP]=]
         will handle this in its own way.
     - The server now does whatever it would otherwise do upon successful authentication -- return a success page, set
@@ -3913,6 +3962,13 @@ Axel Nennker, Kimberly Paulhamus, Adam Powers, Yaron Sheffer, Mike West, Jeffrey
     "status": "FIDO Alliance Review Draft"
   },
 
+  "FIDO-UAF-AUTHNR-CMDS": {
+    "authors": ["R. Lindemann", "J. Kemp"],
+    "title": "FIDO UAF Authenticator Commands",
+    "href": "https://fidoalliance.org/specs/fido-uaf-v1.1-id-20170202/fido-uaf-authnr-cmds-v1.1-id-20170202.html",
+    "status": "FIDO Alliance Implementation Draft"
+  },
+
   "CDDL": {
     "authors": ["C. Vigano", "H. Birkholz"],
     "title": "CBOR data definition language (CDDL): a notational convention to express CBOR data structures",