# Tag: maxant

## Blog Piracy…

The internet never ceases to amaze me... For it appears someone at ease with a cyrillic language is copying my blog word for word:     http://rational_software_architect.softblog.biz/category/work/page/2/ I guess I shall take it as a compliment. I also guess they are just an RSS subscriber and their blog gets updated automatically, so perhaps all of my future postings will have copyright notices in them :-( So, this posting is Copyright 2008, Ant Kutschera! UPDATE: Excellent - I see the site has been taken down! I wonder if its because of the email I sent to their provider, or because they just got bored? Probably the latter :-( If you notice that the site is ever up again, please post a comment below to inform me. Thanks!

## Image Encryption II – Steganography

See the old post. Apparently this is called steganography and is a well researched field! That just proves you how hard it is to invent anything new. Anyway, I have optimised the algorithm and build a website dedicated to it: http://stega.maxant.co.uk.

## Image Encryption

Problem The trouble with encrypting documents is that its quite obvious that they have been encrypted which makes people want to decrypt them. So what about some kind of sexy algorithm that encodes a message within a picture? If the picture only gets slightly changed, then no one will ever realise it contains a secret message, since it looks to all intents and purposes like its a genuine picture. Analysis So, an evenings hacking later and I've come up with an algorithm that does it. The program takes an image file (gif, jpeg, etc) and outputs a bitmap (it cannot be output to a format that compresses with loss like JPEG, otherwise its not possible to decrypt the message since what gets saved is saved with bits lost). Here is an example of a red image that has been modified to contain a message: OK, if you look close (see below which is zoomed in) you can see the modified dots. But its just an example. So here is a photo that has been modified to contain a different secret message: Again, without zooming in, its hard to see the changes. Below is a zoomed in version. You can see the changes as speckled dots. The algorithm has been tuned to try and match the changes to the pixels around the changed pixel. If the surrounding area is blue, the change will be blue, whereas if the area around the change is red, the result will be a red pixel.…

## Login doesn’t appear to work?

I've come across the following problem in IE7 in several products which I initially commented on at the MVN Forum forum (incidentally MVN Forum is a great open source Java Web Forum). Here is a copy: First, thanks for MVNForum - I've used it before, and I have now come back 4 years later to use it again. Its perfect for an all Java platform! But I have a strange bug, which I have figured out. For some reason, with IE7, Tomcat 5.5.9 (and later), MySQL 4.1.x, I find that with IE7 only (not Firefox), it is putting the jsessionid into the URL instead of using a cookie. I have tried changing all the settings in MVN as well as in IE, but it still uses URL rewriting when using my site, even though the cookies work perfect on this forum... I can't figure that bit out... Anyway, I debugged into MVNForum to see what was going on, and I noticed that after one enters their login details, it sends a redirect. In this redirect, the "redirect-to URL", does not contain the jsessionid, and so a new session is started. That means users cannot then do admin, or whatever, depending on user permissions, because the server thinks its a new session and wants them to authenticate again. I used the debugger and on line 426 of com.mvnforum.user.UserModuleProcessor (right at the bottom of the process(HttpServletRequest, HttpServletResponse) method), I modified the value of the responseURI in the JVM, to include ";jsessionid=XXX" where…