Re: [xcbf] Interpretation of the CS under ballot

["Phillip H. Griffin" <phil.griffin@asn-1.com>]

Alessandro,

By these remarks, you seem very confused. Please
see below.

Alessandro Triglia wrote:

>Phil, All,
>
>Please confirm my interpretation of the XCBF CS document in the
>following two areas:
>
>1) Use of BASE64
>2) Use of CXER vs. BASIC-XER
>
>
>As for (1), my interpretation is that  ***BASE-64 must NOT be used in
>actual encodings and message exchanges***,  despite the sentence (line
>1542) that mentions use of BASE-64 for certificates to  "minimize their
>size when represented using XML markup" 
>  
>
The document states clearly at line 1018 that for both the "crls" and
"certificates" components of  type "SignedData",  

"This component shall contain a Base64 armored value. "

This is the opposite of your interpretation.

>As for (2), my interpretation is that  ***CXER, and only CXER, must be
>used for encoding the WHOLE messages***,  despite the numerous sentences
>such as  "This value is always encoded using the XML Encoding Rules"
>and the numerous exampes of BASIC-XER encoding.
>  
>
Clearly, since CXER is a subset of XER, CXER may be used to
encode entire messages. But this is not required. As you say above,
there are numerous sentences in the document such as

"This value is always encoded using the XML Encoding Rules"

and it is these sentences that specify all of the CXER requirements.

If you carefully examine all cases, you will see that a canonical
encoding of XER is only required for cryptographic processing
of protected message components, and not for the message
wrapper.

This requirement is identical for the same message schemas when
they are encoded in BER and DER in X9.84. This should come as
no surprise, as it is common practice in many cryptographic protocols.

The idea is to give implementers flexibility in what they send in all
places in the message where doing so does not affect inter working
of implementations. Where additional rigor is required, a canonical
encoding is specified.

As an example that may be familiar to many people involved in
security, consider X.509 certificates. The signed content must be
encoded in the canonical DER encoding rules. But the wrapper
that encapsulates the signed content may be encoded using the
Basic Encoding Rules of ASN.1. XCBF signed objects are
treated the same.

Phil

>I think that, if my interpretations above are the same as other
>people's, the current imprecisions in the document should not prevent
>its progress.  However, I strongly wish that assurance.
>
>Alessandro
>
>
>
>  
>