the revision 5 and 6 encryption algorithms specify the presence of additional encryption material named 'oe' and 'ue'. it turns out this is not always required so will now default to null if not present. this also adds support for those values being in hex rather than normal string format.
tidies up some commenting on the xynode class, moves public methods below constructors and adds xy to the resharper list of abbreviations for the solution.
cid fonts may contain a registry, ordering and supplement to identify the font. we were checking for string registry and ordering tokens but failing on hex tokens.
for encrypted documents we now decrypt hex data.
using an online tool to encrypt a simple document with aes-128 seems to add the dictionary type cryptalgorithm rather than cryptfilter. i couldn't find any references to cryptalgorithm in the spec or pdfbox but it seems to work ok when treated as equivalent to cryptfilter.
there are situations where the string derived from a hex token has a different length to the underlying bytes, for example if the hex token contains the '\0' byte, the encryption algorithm needs to use the raw bytes rather than the 'stringified' bytes. this change passes raw bytes for hex tokens for both the user and owner password keys.
