On Wed, Sep 04, 2019 at 09:02:06AM +0200, Peter van der Stok wrote:
> I concluded on the pruned .
>
> Peter
> Jim Schaad schreef op 2019-09-03 20:48:
>
> > I have pruned and tossed in a few [JLS] comments.
> >
> > Jim
> >
> > FROM: Peter van der Stok <stokc...@bbhmail.nl>
> > SENT: Tuesday, September 3, 2019 5:18 AM
> > TO: Benjamin Kaduk <ka...@mit.edu>
> > CC: Jim Schaad <i...@augustcellars.com>;
> > draft-ietf-ace-coap-est....@ietf.org; consulta...@vanderstok.org;
> > ace@ietf.org
> > SUBJECT: Re: [Ace] AD review of draft-ietf-ace-coap-est-12 part 2
> >
> > Hi Ben,
> >
> > the last part of the responses to your thorough review.
> > Apart from nits you found some "nice" mistakes.
> >
> > the openssl example make me worry a bit.
> >
> > See below.
> >
> > Peter
> > _______________________________________________________________________
> >
> > SignedData is signed by the party that generated the private key,
> > which may be the EST server or the EST CA. The SignedData is further
> > protected by placing it inside of a CMS EnvelopedData as explained in
> > Section 4.4.2 of [RFC7030]. In summary, the symmetrically encrypted
> >
> > .... if the SignedData is not the outermost container, then we don't care
> > what the relevant Content-Format for it is; we only care about the
> > Content-Format for the EnvelopedData.
> >
> > <pvds>
> >
> > s/ SignedData is signed/SignedData, placed in the outermost container, is
> > signed/
> >
> > s/ The SignedData is further protected by placing it inside of a CMS
> > EnvelopedData/
> >
> > SignedData placed within the Enveloped Data does not need additional
> > signing/
> >
> > </pvds>
> >
> > Also, did we explicitly consider and reject AuthEnvelopedData?
> >
> > <pvds>
> >
> > Not sure about this
> >
> > [JLS] As a CMS person, I would consider the use of EnvelopedData and
> > AuthEnvelopedData to be equivalent. Which of these is used is totally
> > dependent on what algorithm is used for encryption. If one requires the
> > use of AES-GCM or AES-CCM then one has no choice but to use
> > AuthEnvelopedData. If one wants to use AES-CCM ten one has no choice but
> > to use EnvelopedData. Everybody is slowly moving from EnvelopedData to
> > AuthEnvelopedData just because everybody is changing algorithms. I do not
> > remember any discussions about this, but AuthEnvelopeData is generally
> > going to be the more correct value here. I will also note that there is a
> > space between Enveloped and Data which is not CMS.
> >
> > <pvds2>
> > I don't do anything here
> > </pvds2>
I was reading Jim as suggesting to make a change here (though exactly what
change, I'm not sure).
> > </pvds>
> >
> > encryptedKey attribute in a KeyTransRecipientInfo structure.
> > Finally, if the asymmetric encryption key is suitable for key
> > agreement, the generated private key is encrypted with a symmetric
> > key which is encrypted by the client defined (in the CSR) asymmetric
> >
> > In the key-agreement case, the symmetric key-encryption key is the
> > result of the key-agreement operation, no? In which case it is not
> > itself encrypted, but rather the server's ephemeral public value is
> > sent.
> >
> > <pvds>
> >
> > In RFC7030 the text says: the EnvelopedData content is encrypted using a
> > randomly
> >
> > generated symmetric encryption key (that means ephemeral I assume). The
> > cryptographic strength of
> >
> > the symmetric encryption key SHOULD be equivalent to the clientspecified
> >
> > asymmetric key.
> >
> > However, I see no explicit relation with the ephemeral public value.
> >
> > I don't know what to do here; probably insert the 7030 text.
> >
> > [JLS] Ben, you do not have the correct view of the key-agreement case. It
> > does a key agreement -> KDF -> KeyWrap -> Content. There is always a key
> > wrap step between the key agreement and the content encryption key.
> > <pvds2>
> > Also here I see no room for improvement then.
> > <pvds2>
> >
> > </pvds>
> >
> > public key and is carried in an recipientEncryptedKeys attribute in a
> > KeyAgreeRecipientInfo.
> >
> > [RFC7030] recommends the use of additional encryption of the returned
> > private key. For the context of this specification, clients and
> > servers that choose to support server-side key generation MUST
> > support unprotected (PKCS#8) private keys (Content-Format 284).
> > Symmetric or asymmetric encryption of the private key (CMS
> > EnvelopedData, Content-Format 280) SHOULD be supported for
> > deployments where end-to-end encryption needs to be provided between
> > the client and a server. Such cases could include architectures
> > where an entity between the client and the CA terminates the DTLS
> > connection (Registrar in Figure 4).
> >
> > This carefully says nothing about recommendations for use, only for
> > software support. Are we letting 7030's recommendation for use of
> > encryption stand? It's probably worth being explicit, either way.
> >
> > <pvds> I did not find any recommendation for use in RFC7030 apart the
> > responsibility of the server for generating random numbers. The
> > recommendations at the top of section 5.8 of the draft seem adequate in my
> > opinion. The alternative is classifying the applications; unless you see a
> > better way to do this.
> >
> > </pvds>
> >
> > Why OPTIONAL? (Also, nit: OPTIONALLY isn't a 2119 keyword; only OPTIONAL.)
> >
> > client. For example, it could be configured to accept POP linking
> > information that does not match the current TLS session because the
> > authenticated EST client Registrar has verified this information when
> > acting as an EST server.
> >
> > This is close enough to a literal quote that we might think about
> > actually quoting and using quotation marks.
> > nit: s/POP/PoP/ if we don't do the literal quote.
> >
> > <pvds>
> >
> > Hope my co-authors will react to this
> >
> > [JLS] I would disagree with the nit.
> >
> > [JLS] I would agree with the nit on OPTIONALLY being wrong, but I think
> > that it ought to be at least a SHOULD if not a MUST for the use of COAPS as
> > it is terminating the connection. The only exception would be in there is
> > internal authentication for the EST request.
> > <pvds2>
> > Suggest to use SHOULD and not distinguish between terminating or not.
> > <pvds2>
I'm not 100% sure I understand the proposal, but if I do, it seems okay.
I'll just have to look at the new rev when it comes out, I suppose.
-Ben
> > </pvds>
> >
> > Section 9.1
> >
> > I think we probably need this document as a reference for all the
> > allocations; as the document effectuating the registration, we are still
> > of interest even if most details of content encoding lie elsewhere.
> >
> > [JLS] No response from Peter?
> > <pvds2>
> > Sorry, misunderstood. Will add <thisdocument>
> > </pvds2>
> >
> > Appendix A.3
> >
> > I'm having trouble validating the private key in the PKCS#8 component:
> > asn1parse says:
> >
> > <pvds>
> >
> > As input I used recently a hex dump of Wt1234.key.der:
> >
> > 308187020100301306072a8648ce3d020106082a8648ce3d030107046d30
> > 6b020101042061336a86ac6e7af4a96f632830ad4e6aa0837679206094d7
> > 679a01ca8c6f0c37a14403420004c8b421f11c25e47e3ac57123bf2d9fdc
> > 494f028bc351cc80c03f150bf50cff958d75419d81a6a245dffae790be95
> > cf75f602f9152618f816a2b23b5638e59fd9
> >
> > I used openssl pkey -in Wt1234.key.der -text -noout -inform der\
> >
> > -passin pass:watnietweet
> >
> > [JLS] I would lose the password on the key if possible.
> >
> > <pvds2>
> > Right, It means changing the whole chain of certificates. and redoing the
> > examples.
> > But I understand the reason, being confronted with the disassembly failure.
> > </pvds2>
> >
> > The password is may be prohibitive?
> >
> > Resulting in:
> > Private-Key: (256 bit)
> > priv:
> > 61:33:6a:86:ac:6e:7a:f4:a9:6f:63:28:30:ad:4e:
> > 6a:a0:83:76:79:20:60:94:d7:67:9a:01:ca:8c:6f:
> > 0c:37
> > pub:
> > 04:c8:b4:21:f1:1c:25:e4:7e:3a:c5:71:23:bf:2d:
> > 9f:dc:49:4f:02:8b:c3:51:cc:80:c0:3f:15:0b:f5:
> > 0c:ff:95:8d:75:41:9d:81:a6:a2:45:df:fa:e7:90:
> > be:95:cf:75:f6:02:f9:15:26:18:f8:16:a2:b2:3b:
> > 56:38:e5:9f:d9
> > ASN1 OID: prime256v1
> > NIST CURVE: P-256
> >
> > $ unhex|openssl asn1parse -inform der
> > 308187020100301306072a8648ce3d020106082a8648ce3d030107046d30
> > 6b02010104200b9a67785b65e07360b6d28cfc1d3f3925c0755799deeca7
> > 45372b01697bd8a6a144034200041bb8c1117896f98e4506c03d70efbe82
> > 0d8e38ea97e9d65d52c8460c5852c51dd89a61370a2843760fc859799d78
> > cd33f3c1846e304f1717f8123f1a284cc99f
> > 0:d=0 hl=3 l= 135 cons: SEQUENCE
> > 3:d=1 hl=2 l= 1 prim: INTEGER :00
> > 6:d=1 hl=2 l= 19 cons: SEQUENCE
> > 8:d=2 hl=2 l= 7 prim: OBJECT :id-ecPublicKey
> > 17:d=2 hl=2 l= 8 prim: OBJECT :prime256v1
> > 27:d=1 hl=2 l= 109 prim: OCTET STRING [HEX
> > DUMP]:306B02010104200B9A67785B65E07360B6D28CFC1D3F3925C0755799DEECA745372B01697BD8A6A144034200041BB8C1117896F98E4506C03D70EFBE820D8E38EA97E9D65D52C8460C5852C51DD89A61370A2843760FC859799D78CD33F3C1846E304F1717F8123F1A284CC99F
> >
> > which doesn't look like an RFC5208 PrivateKeyInfo:
> >
> > PrivateKeyInfo ::= SEQUENCE {
> > version Version,
> > privateKeyAlgorithm PrivateKeyAlgorithmIdentifier,
> > privateKey PrivateKey,
> > attributes [0] IMPLICIT Attributes OPTIONAL }
> >
> > Version ::= INTEGER
> >
> > PrivateKeyAlgorithmIdentifier ::= AlgorithmIdentifier
> >
> > PrivateKey ::= OCTET STRING
> >
> > Attributes ::= SET OF Attribute
> >
> > due to the lack of OID for privateKeyAlgorithm, etc.
> > (`openssl pkcs8` also chokes on it, but I don't have a working example and
> > can't rule out user error there.)
> >
> > Even that giant OCTET STRING 27 bytes in doesn't seem to match a
> > PrivateKeyInfo:
> >
> > $ unhex|openssl asn1parse -inform der -strparse 27
> > 308187020100301306072a8648ce3d020106082a8648ce3d030107046d30
> > 6b02010104200b9a67785b65e07360b6d28cfc1d3f3925c0755799deeca7
> > 45372b01697bd8a6a144034200041bb8c1117896f98e4506c03d70efbe82
> > 0d8e38ea97e9d65d52c8460c5852c51dd89a61370a2843760fc859799d78
> > cd33f3c1846e304f1717f8123f1a284cc99f
> > 0:d=0 hl=2 l= 107 cons: SEQUENCE
> > 2:d=1 hl=2 l= 1 prim: INTEGER :01
> > 5:d=1 hl=2 l= 32 prim: OCTET STRING [HEX
> > DUMP]:0B9A67785B65E07360B6D28CFC1D3F3925C0755799DEECA745372B01697BD8A6
> > 39:d=1 hl=2 l= 68 cons: cont [ 1 ]
> > 41:d=2 hl=2 l= 66 prim: BIT STRING
> >
> > though the OCTET STRING does have the private key and the BIT STRING has
> > the public key's contents as depicted in C.3 (details of that too boring
> > to show).
> >
> > So I have to wonder if I'm messing something up, somewhere.
> >
> > Appendix B.1
> >
> > Should we be using the same Token value in two different exchanges in
> > this document?
> >
> > <pvds>
> >
> > No opinion
> >
> > [JLS] As long as the Token values are not in the same exchange, this makes
> > no difference. Tokens are reused after an amount of time in CoAP.
> >
> > <pvds2>
> > No extra text, I gather
> > </pvds2>
> >
> > </pvds>
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