Hashing Elements

[Mike King]

Is there a way to create a hash of an element with all of its descendants? I want to uniquely identify an element within a XML document not by its position but by its content (not concatenated string values). Something like a hashed Infoset of an element in a Base64 format.

The reason why I want to do this is because different users of the document apply different values to the elements in the document.

Right now, I'm running the XML file through a MD5 algorithm which produces a hash of the file. Then, I save that hash to a file with the values the user applys to that document, but this approach doesn't allow for the elements to change their position within the document.

I know XML Digital Signatures might be what I want, but I don't know where to begin. I'm currently using MSXML4 and .NET for my XML work. Is where any hope for me?

 

[FLEB]

Regarding this well-known quote, often attributed to Mike King's famous "Fri, 30 Jul 2004 13:36:10 -0400" speech:

Is there a way to create a hash of an element with all of its descendants? I want to uniquely identify an element within a XML document not by its position but by its content (not concatenated string values). Something like a hashed Infoset of an element in a Base64 format.

The reason why I want to do this is because different users of the document apply different values to the elements in the document.

Right now, I'm running the XML file through a MD5 algorithm which produces a hash of the file. Then, I save that hash to a file with the values the user applys to that document, but this approach doesn't allow for the elements to change their position within the document.

I know XML Digital Signatures might be what I want, but I don't know where to begin. I'm currently using MSXML4 and .NET for my XML work. Is where any hope for me?

You could just pull out indicative portions of the data, sorted into a particular order, either via a processing script, or with an XSLT transform, then MD5 that. If things might change order, just force them into order with a sort.