uuencode(my favorite commandline encoder) to generate the BASE64 string. But the blogeditor ruins it by inserting <br/> after each line in the BASE64 text so I will not show here, but fine from a local file on my harddrive. But then i found a hint that showed me how to disable these automatic line breaks and voilá:
I can add it as an image and the upload goes okay:
but in the blog post the line breaks are introduced again. I looks like it time to investigate some of the other options for posting.