On Thu, Oct 17, 2019 at 07:08:49AM -0700, Benjamin Kaduk via Datatracker wrote: > > > ---------------------------------------------------------------------- > DISCUSS: > ---------------------------------------------------------------------- > > % (1) The text of the document suffers from lack of clarity throughout about > % whether the nonce-ful operation is mandatory or not, with several > % figures and discussions making declarative statements about nonce usage > % and others saying that nonce usage is optional. (See COMMENT.) > > [keep in mind when reading]
This was just supposed to be a note to myself and should be ignored; I was in a hurry and forgot to trim it before pushing "send". Sorry about that. I also have some more comments that didn't make it into my ballot position; please consider them as well. I will put them in the datatracker for posterity, but will have it not generate an additional mail since the mostly-duplicate contents would be confusing. Section 2 Should the "Drop Ship" arrow in Figure 1 be unidirectional instead of bidirectional? 3. Request to join the discovered registrar. A unique nonce is included ensuring that any responses can be associated with this particular bootstrapping attempt. This still seems to assume nonce-ful operation, which IIUC remains required for pledge voucher-requests; only registrar-voucher-requests have the option of being nonceless. So, this seems okay as-is, right? 4. Imprint on the registrar. This requires verification of the manufacturer service provided voucher. A voucher contains nit: hyphenate "manufacturer-service-provided" Section 2.3.1 The serialNumber fields is defined in [RFC5280], and is a SHOULD field in [IDevID]. IDevID certificates for use with this protocol MUST include the "serialNumber" attribute with the device's unique serial number (from [IDevID] section 7.2.8, and [RFC5280] section 4.1.2.4's list of standard attributes). This is 4.1.2.2 (or just 4.1.2) from RFC 5280. Section 2.4 I note that both Figure 2 and Figure 4 have a step labeled "Identity", but the description accompanying Figure 2 describes the step as "Identify itself"; perhaps the 'f' form is more appropriate everywhere? Section 2.8 Note that the registrar can only select the configured MASA URL based on the trust anchor -- so manufacturers can only leverage this approach if they ensure a single MASA URL works for all pledge's associated with each trust anchor. nit: s/pledge's/pledges/ Section 3 Voucher-requests are how vouchers are requested. The semantics of the vouchers are described below, in the YANG model. nit: semantics of vouchers, or voucher requests? Section 3.3 Figure 6: JSON representation of example Voucher-Request I suggest adding "(unsigned)" or "prior to CMS wrapping". Section 3.4 refine "voucher/assertion" { mandatory false; description "Any assertion included in voucher requests SHOULD be ignored by the MASA."; If this is true, why do we propagate the assertion from pledge voucher-request to registrar voucher-request? Section 4.1 Each possible proxy offer SHOULD be attempted up to the point where a voucher is received: while there are many ways in which the attempt may fail, it does not succeed until the voucher has been validated. nit: I suggest "valid voucher is received". Section 5 o The pledge requests and validates a voucher using the new REST calls described below. nit: I think the validation is local and does not use the REST call. o The registrar forwards the voucher to the pledge when requested. I suggest "validates and forwards" to cover the case where the registrar applies policy. Section 5.2 nonce: The pledge voucher-request MUST contain a cryptographically strong random or pseudo-random number nonce. (see [RFC4086]) Doing so ensures Section 2.6.1 functionality. The nonce MUST NOT be This section reference reads kind of strangely. (Also, full stop after parenthetical, not before.) proximity-registrar-cert: In a pledge voucher-request this is the first certificate in the TLS server 'certificate_list' sequence (see [RFC5246]) presented by the registrar to the pledge. That is, it is the end-entity certificate. This MUST be populated in a pledge voucher-request if the "proximity" assertion is populated. nit: there is no "proximity" field to be populated; it's the "assertion" field that's populated with the value "proximity". Section 5.5 serial-number: The serial number of the pledge the registrar would like a voucher for. The registrar determines this value by parsing the authenticated pledge IDevID certificate. See Section 2.3. The registrar MUST verify that the serial number field it parsed matches the serial number field the pledge provided in its voucher-request. This provides a sanity check useful for detecting error conditions and logging. The registrar MUST NOT simply copy the serial number field from a pledge voucher request as that field is claimed but not certified. (Just to be clear, the serial-number field is optional in the pledge's voucher-request.) Section 5.6.2 intervals according to the backoff timer described earlier. Attempts SHOULD be repeated as failure may be the result of a temporary inconsistently (an inconsistently rolled registrar key, or some other mis-configuration). The inconsistently could also be the result an active MITM attack on the EST connection. nit: only one of these "inconsistently"s is correct; the others should be "inconsistency". Section 5.8 although it results in additional network traffic. The relying MASA implementation MAY leverage internal state to associate this request with the original, and by now already validated, voucher-request so as to avoid an extra crypto validation. It seems that doing so would turn the voucher-request into a bearer token for retrieving audit-log information (if the MASA accepts unauthenticated clients). Section 5.8.2 If the "pinned-domain-cert" certificate includes the SubjectKeyIdentifier (Section 4.2.1.2 [RFC5280]), then it is to be used as the domainID. If not, then it is the SPKI Fingerprint as described in [RFC7469] section 2.4 is to be used. This value needs to be calculated by both MASA (to populate the audit-log), and by the Registrar (to recognize itself). nit: maybe "to recognize itself in the audit log"? Section 5.9 The pledge SHOULD follow the BRSKI operations with EST enrollment operations including "CA Certificates Request", "CSR Attributes" and "Client Certificate Request" or "Server-Side Key Generation", etc. This is a relatively seamless integration since BRSKI REST calls (I think we decided to not call this REST.) Section 7.3 4. A registrar MAY ignore unrecognized nonceless log entries. This could occur when used equipment is purchased with a valid history being deployed in air gap networks that required permanent vouchers. "nonceless" and "permanent" are related but subtly different concepts, given the potential for an expiration date in a nonceless voucher. Section 7.4.3 As a third option, the manufacturer's trust anchors could be entirely overwitten with local trust anchors. A factory default would never restore those anchors. This option comes with a lot of power, but also a lot of responsability: if the new anchors are lost the manufacturer may be unable to help. nit: perhaps we refer to the private key portions of the anchors. Section 11 I am somewhat embarassed that I did not previously note that the mechanism used to generate the domainID needs to be second-preimage-resistant or an attacker can claim to be a registrar for a domain that already exists. Section 11.2 Although the nonce used by the Pledge in the voucher-request does not require a strong cryptographic randomness, the use of TLS in all of the protocols in this document does. We discuss the need for strong randomness in the nonce in Section 11.3, so it's not clear this is actually true. Thanks! -Ben _______________________________________________ Anima mailing list Anima@ietf.org https://www.ietf.org/mailman/listinfo/anima