Hi All, We just released an interactive graph that shows the relationship between the root-CAs of the Mozilla root-store and their intermediates at http://notary.icsi.berkeley.edu/trust-tree/.
Root-CAs are pictured as red nodes, intermediate CAs are green. The node diameter scales logarithmically with the number of certificates signed by the node. Similarly, the color of the green nodes scales proportional to the diameter. The data source for this graph is the ICSI SSL notary [1], which was previously mentioned on this mailing list. We have been passively monitoring the Internet uplinks of a number of (mostly) edu networks for certificate and SSL information for about 10 months. Clicking on individual nodes reveals additional information about the CAs, especially the number of valid child certificates we currently know for it. In the graph, the CA that directly signed the largest number of certificates is the Go Daddy Secure Certification Authority, an intermediate of GoDaddy. Our current dataset contains over 74,000 certificates that it signed. The DFN-Verein CA has signed the largest number of intermediate CA certificates. As you might know it provides certificates for many German higher education and research institutions. It creates a unique sub-CA for each institution for which it issues certificates. Our data set currently contains more than 200 sub-CAs of it. The DFN does this for administrative reasons. The control of the private keys of all sub-CAs remains at the DFN and they check each certificate request. If you have any questions or comments about this, please let us know. Bernhard [1]: http://notary.icsi.berkeley.edu/
