MachineTagLinkFingerprint

Machine tags (MachineTag) are just standard tag with extra information to extend the information in the tag. They are called machine tags because there are often use by program to get extra information from a specific work determined by its URI/location.

Blog entry about linkfingerprint : 2008-05-02 Linkfingerprint MachineTag

Link Fingerprint Machine Tags

Usage

The initial idea came from the Internet-Draft named Link Fingerprints:

   Link Fingerprints provides a backward-compatible technique for
   resource providers to ensure that the resource originally referenced
   is the same as the resource retrieved by an end user.  Changes are
   localized to the user agent retrieving the resource, and this can
   automatically prevent the end user from accidentally using unintended
   modified data while being transparent to the end user if the data is
   correct.

In the Internet-Draft, the fingerprint information is located in the URI using a specific anchor mechanism. The main issue is to keep the URI readable and meaningful while keeping the integrity of the linked object. I had the idea to move the information in a system tag to avoid the issue of URI containing the fingerprint information. The additional idea is to benefit from the mass of users tagging a specific URI to validate his integrity. But also introducing the trust on the software based of the social network available in the bookmarking services like del.icio.us.

The link fingerprint machine tag also supports an additional stronger integrity format not described in the initial draft using a simple OpenPGP? detached signature.

namespace : linkfingerprint (?)

A single URI can be tagged one time or more using the below predicate value. For example, you can tag an URI at the same time using one-way hashing in MD5 and OpenPGP? detached signature.

predicate and value

predicate and value are case insensitive.

• hash="type:value"
  • defined type are :

 md5 
 sha1 
 sha-224 
 sha-256 
 sha-384 
 sha-512 

• openpgp="value" value is the base64 encoded value of the OpenPGP? detached signature

example in del.icio.us

• http://del.icio.us/adulau/linkfingerprint (an experiment with the URL of my OpenPGP? public key)

software using it

• linkfingerprint.py - a linkfingerprint python script relying on del.icio.us

 action :

 --lookup (default) URI
 --add URI

discussion about OpenPGP detached signature

- (1)a standard Base64 encoding of the binary detached signature.

The major problem raised by OpenPGP? detached is the size of the signature. Various tagging solution has a limit for the size of a tag.