Data format guessing of data within Base64Data tag

[Daniel Martín Lambea <dmlambea@tenerife.es>]

Dear all,

I have found an implementation of the DSS standard that refuses to sign an octet stream provided as base 64 string within a <dss:Base64Data>...</dss:Base64Data> tag, as long as the octet stream can be interpreted as XML. In other words, if one tries to provide a base64 encoding of the following sample string '<sample>Hello, world!</sample>' into the <dss:Base64Data> tag, the implementation denies the signing operation with an error saying that "The data is XML and therefore must be provided within <Base64XML> tag".

AFAIK, the standard (http://docs.oasis-open.org/dss/v1.0/oasis-dss-core-spec-v1.0-os.pdf) paragraph 3.3.4, "Process variant for <Base64Data>" says that the octed stream must not be processed. The ambiguity here is in the parsing that the implementation is doing for the provided base64 data. "Parsing" is not "processing", as far as no modification is being performed over the data. But since the implementation is trying to guess the format of the data, no signing operation can be done over an arbitrary octet stream, whenever the octet stream has XML look & feel.

Is that implementation correct? I mean, is the implementation responsible of parsing the octet stream within Base64Data to ensure it MUST NOT be XML data?

Kind regards,
Daniel M. Lambea

Unidad Orgánica de Desarrollo
Instituto Insular de Informática y Comunicaciones
Excmo. Cabildo Insular de Tenerife
C/ Clavel, Nº2, 38003 Santa Cruz de Tenerife
Tfno. 922239362