2 Replies Latest reply on Nov 21, 2011 10:16 PM by mark_erickson

    XMP Metadata Identification Help


      To all-


      Is this XMP value unique to a particular image, software or camera? Is there a way to decode the value or do any sort of analysis on the information contained within?


      Im in the middle of an important investigation and part of it hinges on a few digital images, one of which contains this XMP value.


      Any help is appreciated.








        • 1. Re: XMP Metadata Identification Help
          Jörg Ehrlich Adobe Employee

          Please see the official XMP specification for an explanation of those properties.




          • 2. Re: XMP Metadata Identification Help
            mark_erickson Level 1

            The simple answer, there is no requirement on how this unque value is created. You might be able to extract some information, but depends upon the "scheme" by which it was created.


            Reading the XMP specification you will find the following...


            An ID should be a GUID/UUID-style ID, which is a large integer that is guaranteed to be globally unique (in practical terms, the probability of a collision is so remote as to be effectively impossible). Typically 128- or 144-bit integers are used, encoded as 22 or 24 base- 64 characters.


            XMP does not require any specific scheme for generating the unique number. There are various common schemes available for that purpose, such as:

            • Using physical information such as a local Ethernet address and a high resolution clock.

              NOTE: When creating a unique ID, applications must consider tradeoffs between privacy and the desire to create an audit trail. Adobe applications favor privacy and do not include Ethernet addresses.

            • Using a variety of locally unique and random data, then computing an MD5 hash value. This avoids privacy concerns about the use of Ethernet addresses. It also allows for regeneration of the ID in some cases; for example if the MD5 hash is computed using the image contents for a resource that is a digital photograph.





            - Mark