[cabf_validation] [EXTERNAL]Re: Ballot Proposal: Validation Method in certificatePolicies
Ryan Sleevi
sleevi at google.com
Thu Aug 16 11:02:54 MST 2018
Ideally, we'd keep the syntax something that CAs and RPs can just paste in
to their ASN.1 modules. To that end, both the ellipses and periods in the
named bitmask names (method3.2.2.4.1) would be ideal to avoid. Whether we
give them semantic identifiers (domainAuthorizationDocument (5)) or not I
don't have any strong feelings about, I'd just love to make sure we've got
clean syntax that is valid :)
On Thu, Aug 16, 2018 at 1:54 PM Wayne Thayer <wthayer at mozilla.com> wrote:
> Here some new language that attempts to incorporate everyone's feedback:
>
>
> https://github.com/wthayer/documents/commit/73bece3c6c506e0fdd50b86fee42ac769a016fe5
>
> My use of ellipses ("...") in the enumerations is surely a syntax
> violation, but I think it helps to clarify the layout of the BIT STRINGs
> without adding a maintenance burden to the document.
>
> On Thu, Aug 16, 2018 at 9:23 AM Ryan Sleevi <sleevi at google.com> wrote:
>
>> If we assume the concerns are:
>> 1) Simplicity of implementation for CAs
>> 2) Maximum compatibility with clients
>> 3) Minimal size encoding in the average and best cases
>> 4) Ease in maintenance overhead for the Forum
>>
>> Then we end up with something like (using some of the RFC 5912 class
>> templates)
>>
>> -- Option 1: This just uses them as bit strings without enumerating the
>> reasons, and
>> -- prose would be attached to describe which bit to set, using the
>> terminology from
>> -- X.680 regarding 'leading' bit (e.g. X.680 21.2 / 21.4)
>> DNSValidationMethods ::= BIT STRING
>> IPValidationMethods ::= BIT STRING
>>
>> -- Option 2: This provides an enumeration for semantic names for the
>> bits. New bits can be added at any time
>> DNSValidationMethods ::= BIT STRING {
>> unused (0),
>> -- This is also optional, and just means we're skipping the leading bit
>> so that the textual
>> -- '1' can align with the named '1' bit.
>> -- It does mean one bit is 'reserved', to the extent that matters to
>> folks, for want of a bit.
>> method1 (1),
>> method2 (2),
>> method3 (3)
>> }
>> IPValidationMethods ::= BIT STRING {
>> method1 (0),
>> -- This demonstrates the other approach
>> method2 (1),
>> method3 (2)
>> }
>>
>> id-cabf-dnsValidation OBJECT IDENTIFIER ::= { /*TBD */ }
>> id-cabf-ipValidation OBJECT IDENTIFIER ::= { /* TBD */ }
>> ext-cabf-dnsValidation EXTENSION ::= { SYNTAX DNSValidationMethods
>> IDENTIFIED BY id-cabf-dnsValidation }
>> ext-cabf-ipValidation EXTENSION ::= { SYNTAX IPValidationMethods
>> IDENTIFIED BY id-cabf-ipValidation }
>>
>>
>> On Thu, Aug 16, 2018 at 12:06 PM Ben Wilson <ben.wilson at digicert.com>
>> wrote:
>>
>>> Never mind, then. I was just responding to the confusion I felt there
>>> was on the validation WG call this morning about how this was going to be
>>> done. Has anyone circulated an example of how this will be encoded in ASN1?
>>>
>>>
>>>
>>> *From:* Ryan Sleevi <sleevi at google.com>
>>> *Sent:* Thursday, August 16, 2018 10:03 AM
>>> *To:* Ben Wilson <ben.wilson at digicert.com>
>>> *Cc:* Tim Hollebeek <tim.hollebeek at digicert.com>; CA/Browser Forum
>>> Validation WG List <validation at cabforum.org>; Corey Bonnell <
>>> CBonnell at trustwave.com>; Wayne Thayer <wthayer at mozilla.com>
>>> *Subject:* Re: [cabf_validation] [EXTERNAL]Re: Ballot Proposal:
>>> Validation Method in certificatePolicies
>>>
>>>
>>>
>>> Ben,
>>>
>>>
>>>
>>> Could you explain why you prefer that method? It would be the most
>>> expensive in terms of size proposed yet, and be second only to relative OID
>>> in complexity for implementations. It also doesn't align with the X.680
>>> guidance. Could you indicate what the factors you were considering in that
>>> solution?
>>>
>>>
>>>
>>> On Thu, Aug 16, 2018 at 11:58 AM Ben Wilson <ben.wilson at digicert.com>
>>> wrote:
>>>
>>> I think we should have one OID extension and then a sequence and then
>>> context-specific strings that map to each validation method used – similar
>>> to what is done for SANs under RFC 5280. Similar to the SAN approach, you
>>> would identify what context-specific type of SAN (domain name or IP
>>> address) we are talking about. (I’m not suggesting that CAs would be
>>> required to have a matching method for each SAN in a certificate, they
>>> could still have just one, however they could if they wanted, or they could
>>> include multiple lines, without one-to-one mapping.)
>>>
>>>
>>>
>>> To illustrate, here is a clip from RFC 5280
>>>
>>>
>>>
>>> SubjectAltName ::= GeneralNames
>>>
>>>
>>>
>>> GeneralNames ::= SEQUENCE SIZE (1..MAX) OF GeneralName
>>>
>>>
>>>
>>> GeneralName ::= CHOICE {
>>>
>>> otherName [0] AnotherName,
>>>
>>> rfc822Name [1] IA5String,
>>>
>>> dNSName [2] IA5String,
>>>
>>> x400Address [3] ORAddress,
>>>
>>> directoryName [4] Name,
>>>
>>> ediPartyName [5] EDIPartyName,
>>>
>>> uniformResourceIdentifier [6] IA5String,
>>>
>>> iPAddress [7] OCTET STRING,
>>>
>>> registeredID [8] OBJECT IDENTIFIER }
>>>
>>>
>>>
>>> I’m also not suggesting that this numbering from RFC 5280 be used.
>>>
>>>
>>>
>>> Ben
>>>
>>>
>>>
>>> *From:* Validation <validation-bounces at cabforum.org> *On Behalf Of *Tim
>>> Hollebeek via Validation
>>> *Sent:* Wednesday, August 15, 2018 11:40 AM
>>> *To:* Corey Bonnell <CBonnell at trustwave.com>; Wayne Thayer <
>>> wthayer at mozilla.com>; CA/Browser Forum Validation WG List <
>>> validation at cabforum.org>
>>> *Subject:* Re: [cabf_validation] [EXTERNAL]Re: Ballot Proposal:
>>> Validation Method in certificatePolicies
>>>
>>>
>>>
>>> I also like the separate extension because IP validated certificates are
>>> pretty rare. I think it’d be nicer not to muck up the 3.2.2.4 list with
>>> attempts to accommodate them.
>>>
>>>
>>>
>>> -Tim
>>>
>>>
>>>
>>> *From:* Corey Bonnell <CBonnell at trustwave.com>
>>> *Sent:* Wednesday, August 15, 2018 12:48 PM
>>> *To:* Wayne Thayer <wthayer at mozilla.com>; CA/Browser Forum Validation
>>> WG List <validation at cabforum.org>; Tim Hollebeek <
>>> tim.hollebeek at digicert.com>
>>> *Subject:* Re: [cabf_validation] [EXTERNAL]Re: Ballot Proposal:
>>> Validation Method in certificatePolicies
>>>
>>>
>>>
>>> Hi Wayne,
>>>
>>> Perhaps create another extension/OID to contain the BIT STRING of
>>> validation methods for IP addresses? Doing so would remove the need to have
>>> a special numbering scheme for IP address validation method numbers and
>>> would be straightforward to process.
>>>
>>>
>>>
>>> Additionally, if a certificate contains only iPAddress SANs, it could
>>> omit the dNSName-specific extension entirely (likewise for a certificate
>>> that contains only dNSNames). Certificates that contain both dNSNames and
>>> iPAddress SANs are rare in practice, so there is no additional space
>>> overhead in the common case.
>>>
>>>
>>>
>>> Thanks,
>>> Corey
>>>
>>>
>>>
>>>
>>>
>>> *Corey Bonnell*
>>>
>>> Senior Software Engineer
>>>
>>>
>>>
>>> *Trustwave* | SMART SECURITY ON DEMAND
>>> https://www.trustwave.com <http://www.trustwave.com/>
>>>
>>>
>>>
>>> *From: *Validation <validation-bounces at cabforum.org> on behalf of Wayne
>>> Thayer via Validation <validation at cabforum.org>
>>> *Reply-To: *Wayne Thayer <wthayer at mozilla.com>, CA/Browser Forum
>>> Validation WG List <validation at cabforum.org>
>>> *Date: *Wednesday, August 15, 2018 at 12:34 PM
>>> *To: *Tim Hollebeek <tim.hollebeek at digicert.com>, CA/Browser Forum
>>> Validation WG List <validation at cabforum.org>
>>> *Subject: *Re: [cabf_validation] [EXTERNAL]Re: Ballot Proposal:
>>> Validation Method in certificatePolicies
>>>
>>>
>>>
>>> To make the BIT STRING encoding work in a single extension, we should
>>> discuss how best to collapse domain and IP address validation methods into
>>> a single "namespace". It might be best to add explicit and unique numbering
>>> to all the domain + IP address methods as part of the ballot to remove the
>>> IP address "any other method". I'd like to avoid the need for a separate
>>> mapping table (e.g. bit position 17 signifies method 3.2.2.5.3).
>>>
>>>
>>>
>>> On Wed, Aug 15, 2018 at 9:22 AM Tim Hollebeek via Validation <
>>> validation at cabforum.org> wrote:
>>>
>>> Yeah, lots of people are going to make the same mistake I did if Method
>>> 6 is represented by bit 5 (not 6! I like my bit numbers to be zero based,
>>> so you can just do the power thing). Off by one errors are so much fun …
>>>
>>>
>>>
>>> But again, I don’t think it’s a huge problem. Only technical people are
>>> staring at this stuff, and they’ll quickly learn which values correspond to
>>> which methods.
>>>
>>>
>>>
>>> -Tim
>>>
>>>
>>>
>>> *From:* Ryan Sleevi <sleevi at google.com>
>>> *Sent:* Wednesday, August 15, 2018 11:32 AM
>>> *To:* Tim Hollebeek <tim.hollebeek at digicert.com>
>>> *Cc:* Doug Beattie <doug.beattie at globalsign.com>; Daymion T. Reynolds <
>>> dreynolds at godaddy.com>; CA/Browser Forum Validation WG List <
>>> validation at cabforum.org>
>>> *Subject:* Re: [cabf_validation] [EXTERNAL]Re: Ballot Proposal:
>>> Validation Method in certificatePolicies
>>>
>>>
>>>
>>>
>>>
>>> On Wed, Aug 15, 2018 at 9:24 AM Tim Hollebeek <
>>> tim.hollebeek at digicert.com> wrote:
>>>
>>> Given that the number of 1 bits is likely low, I don’t think BIT STRING
>>> is that hard to read. It just means that you’re going to have to memorize
>>> that Method 6 is “64” instead of 6. It’s slightly tougher, but if you’re
>>> the sort of person who is capable of staring at raw ASN.1, I think you can
>>> cope.
>>>
>>>
>>>
>>> I'm not sure I understand your point about knowing that "Method 6 is 64".
>>>
>>>
>>>
>>> Method 6 is Bit 6.
>>>
>>> Method 7 is Bit 7.
>>>
>>> Method 139 is Bit 139.
>>>
>>>
>>>
>>> A certificate viewer that does not dive into constructed extensions
>>> would display the extension as its full hex (e.g. with the outer Tag and
>>> Length octets).
>>>
>>> A certificate viewer that does dive into constructed extensions would
>>> display the inner value, typically in either base2 or base16 notation. In
>>> Base2 notation, it's 'easy' to count which bits are set. In Base16
>>> notation, you can easily convert to Base2.
>>>
>>> A certificate viewer that explicitly knows about this extension can:
>>>
>>> - Used named values for methods it recognizes - e.g. as a lookup
>>> table, same as OIDs)
>>>
>>> - Alternatively, note the integer position itself for which bit was
>>> set - e.g. bit 1 = method 1, bit 2 = method 2 etc. - and display that as
>>> such
>>>
>>>
>>>
>>> But regardless, you shouldn't expect to see "Method 6 is 64". You'd
>>> expect 32, at best, but more realistically, 0x20. :)
>>>
>>>
>>>
>>> _______________________________________________
>>> Validation mailing list
>>> Validation at cabforum.org
>>> https://cabforum.org/mailman/listinfo/validation
>>> <https://scanmail.trustwave.com/?c=4062&d=hdb021QJj1WGk3oW4iuneFftb6mTa86AK485jQ3E5A&s=5&u=https%3a%2f%2fcabforum%2eorg%2fmailman%2flistinfo%2fvalidation>
>>>
>>>
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