Archive for the ‘images’ Category

a graphical web of trust

Sunday, September 12th, 2010

I recently stumbled upon sig2dot, a gpg/pgp keyring graph generator. In fact this seems to have been around for some time, but I’d never come across it before. It can be used to generate a graph of all of the signature relationships in a GPG/PGP keyring, and, like other visualisation tools, this graphical image producing program can give new insight into relationships between objects.

The sig2dot program itself is available in the debian/ubuntu repositories in the package called “signing-party”. But unless you want to install a shed load of other unnecessary cruft along with it (exim? for god’s sake, why?), I recommend you simply pull the perl code direct from the author’s site. Along with the sig2dot program itself, you will need “neato” from the graphviz package and “convert” from the wondrous imagemagick package suite. If you don’t already have those installed then it is pretty safe to pull them from your distro’s package repository.

That done, try the following:

first create an ascii graphviz dot file ready for neato

$ gpg –list-sigs –keyring ~/.gnupg./pubring.gpg | sig2dot.pl > ~/.gnupg/pubring.dot

now convert to a postscipt file

$ neato -Tps ~/.gnupg/pubring.dot > ~/.gnupg/pubring.ps

before using imagmagick to convert to a png graphic

$ convert ~/.gnupg/pubring.ps ~/.gnupg/pubring.png

Those of you with gpg keyrings may wish to try it out (and no. I’m not going to show you mine).

kseniya simonova

Saturday, September 4th, 2010

This has absolutely nothing to do with my usual topics but I make no apology for posting this because the artistry is stunningly beautiful. I was sent a link to Kseniya Simonova’s sand art by a correspondent on a mailing list I subscribe to. Apparently the artist is telling the story of a ukrainian family before, during and after the bombing of their town in the second world war.

I understand that Ms Simonova was a contestant on Ukraine’s version of “Britain’s got talent”. This lady has real talent, unlike some of the contestants I have seen on the UK’s version. It looks as if Ukrainian television may be in a better place than ITV.

email address images

Monday, May 3rd, 2010

Adding valid email addresses to web sites is almost always a bad idea these days. Automated ‘bots routinely scan web servers and harvest email addresses for sale to spammers and scammers. And in some cases, email addresses harvested from commercial web sites can be used in targetted social engineering attacks. So, posting your email address to a website in a way which is useful to human being, but not to a ‘bot has to be a “good thing” (TM). One way of doing so is to use an image of an address rather than text itself. Of course this has the disadvantage that the address will not be immediately usable by client email software (unless, of course you defeat the object of the exercise by adding an html “mailto” tag to the image) but it should be no big deal for someone who wants to contact you to write the address down.

There are a number of web sites which offer a (free) service which allows you to plug in an email address and then download an image generated from that address. However, I can’t get over the suspicion that this would be an ideal way to actually harvest valid email addresses, moreover addresses which you could be pretty certain the users did not want exposed to spammers. Call me paranoid, but I prefer to control my own privacy.

There are also a number of web sites (and blog entries) describing how to use netpbm tools to create an image from text – one of the better ones (despite its idiosyncratic look) is at robsworld. But in fact it is pretty easy to do this in gimp. Take a look at the address below:

This was created as follows:

open gimp and create a new file with a 640×480 template (actually any template will do);
select the text tool and choose a suitable font size, colour etc;
enter the text of the address in the new file;
select image -> autocrop image;
select layer -> Transparency -> Colour to Alpha;
select from white (the background colour) to alpha;
select save-as and use the file extension .png – you will be prompted to export as png.

Now add the image to your web site.