[OpenID] Signing method for XRD

Sun Jun 14 17:26:43 UTC 2009

John,

We spent a lot of time looking at ways of simplifying canonicalization  
by having the signature in a separate doc.

This minimally requires a separate network access to get the signature  
document if one wants to check it.

It also presumes that XRD will only be used in applications using http:.

One solution proposed by Google was to include the signature in the  
headers, to reduce accesses.

However this makes deployment at the OP end more difficult, because  
you no longer have just static files,  and may also behave  
unpredictably with proxy's

For simplicity of deployment of the files having a single static file  
seems to be the preference.

We looked at using HTLM form encoding with the XRD body base64 encoded  
but that added unnecessary complexity for people not wanting signatures.
S/MIME PKCS7 and other options were considered but had no clear  
advantage over a constrained form of XML normalization.

Being able to keep the signature and document together has advantages  
for audit logs,  creating XRDS documents for XRI,  using XRD for  
protocols other than HTTP.

If I want to send a XRD as a AX Attribute because some of the  
endpoints are private sending the signature in the document makes life  
much easier.

Infocard pushing a XRD discovery document as the value of a claim also  
benefits from the single document approach.

Peter is not unusually looking farther down the road.

X.509 is a ASN.1 meta-data document that has an enveloped signature.    
Probably not something you want to parse from scratch in Ruby.
X.509 was designed to be flexible and contain may types of meta-data.

It has never really lived up to the design goal.  In practice they are  
not useful for conveying arbitrary meta-data.

I think Peter is imagining that if we have a well understood  
extensible meta-data container XRD, with an enveloped signature like X. 
509 it could replace X.509 certificates.

People on the Shibboleth side of the world are considering such things  
with SAML meta-data.

I will leave the required rant about overthrowing the evil CA  
oppressors to others.

It is possible that signed XRD could play a valuable role in expanding  
trust on the internet in areas where traditional PKI has not stepped  
up to the challenge.

The question is a single human readable document that can be consumed  
both by signature aware and unaware applications the way to go?

Is being compatible with existing XMLDsig libraries and being  
reasonably easy to implement in scripting languages compatible?

XRD has broader use cases than just openID.  We are honestly trying to  
provide a good balance.

John B.
On 14-Jun-09, at 12:47 PM, John Panzer wrote:

> John Bradley wrote:
>>
>> Peter,
>>
>> Yes some of us see the possibility of XRD as signed meta-data being  
>> a useful alternative to X.509 eventually.
>>
>> If we have an signature method that supports enveloping  
>> signatures,  XRD will be more useful for those applications.
>>
>> We can opt for the simplest signing, that of signing the binary  
>> representation of the XRD and keeping the signature in a detached  
>> file.
>> This may make life simpler for scripting languages dealing with  
>> cannonicalization  but at the cost of making it awkward to deal  
>> with in other environments where having the signature in the same  
>> document is very useful.
> For the record, and for those of us not versed in X.509, can provide  
> some use cases and details on how having the signature in the XRD  
> doc is necessary/useful for  for XRD?
>
>
>>
>> Full XMLDsig is ugly because of qnames and other issues.   We are  
>> proposing a constrained implementation that eliminates most of the  
>> cannonicalization complexities,  but is still compatible with  
>> existing libraries.
>>
>> John B.
>> On 10-Jun-09, at 12:10 PM, general-request at openid.net wrote:
>>
>>> Date: Wed, 10 Jun 2009 09:10:44 -0700
>>> From: Peter Williams <pwilliams at rapattoni.com>
>>> Subject: Re: [OpenID] Signing method for XRD
>>> To: Santosh Rajan <santrajan at gmail.com>, "general at openid.net"
>>>  <general at openid.net>
>>> Message-ID:
>>>  <BFBC0F17A99938458360C863B716FE46398DCE8FDD at simmbox01.rapnt.com>
>>> Content-Type: text/plain; charset="us-ascii"
>>>
>>>
>>> my first reaction was ugh - xml-dsig has its own inband mechanism  
>>> for referencing keying material - and here is openid/xrd doing yet  
>>> another standard for verifying signatures and validating the  
>>> supporting keying material (probably poorly).
>>>
>>> My second reaction on reflection was that xml-dsig is rarely used  
>>> to its full potential. Its typically used as a PKCS7 signing and  
>>> sealing emulation modes, with an XML centric view of the world -  
>>> with no particular benefit. But, if xml dsig fully uses its  
>>> external references, and the references are to a world of XRD  
>>> files which are TRUSTED to act as a key distribution mechanism,  
>>> things get rather more interesting. In that world, the XRD is  
>>> becoming a certificate, as we know it - and one whose format and  
>>> semantics would enable it to go beyond the staid ol X.509 cert  
>>> chains and benefit the full expression power of xri queries and  
>>> XRI resolution.
>>>
>>> What the X.509 v3 format work took part (divorcing asymmetric key  
>>> management from dap/ldap resolution), XRI/XRD may be putting back  
>>> together: query-based named-key resolution supporting trust fabric  
>>> meshes.
>>>
>>
>>
>> _______________________________________________
>> general mailing list
>> general at openid.net
>> http://openid.net/mailman/listinfo/general
>>
>

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