Thank you for your letter of the fourth. We can supply the timber you asked about, though not before the end of the month. Yours faithfully,
Turn the magnifier up
The underline beneath the signature is not a line. It is a sentence, written small enough that the eye reads it as a stroke of the pen.
This is the oldest hiding trick on the site that needs no chemistry, no equipment and no agreement: a fine nib, a steady hand, and a reader who owns a lens.
Nothing is encrypted. Anyone who magnifies it can read it. It relies on one thing only: that nobody thinks to look closely at a line.
Small enough to matter
Micro-writing runs all the way from Renaissance scribes squeezing a psalm onto a fingernail to the microdot, which is the same idea with a camera doing the shrinking, to the last digit of a pixel, which is the same idea again with nothing physical left at all.
It also does honest work. Banknotes carry lines of tiny text that look like a rule until you magnify them, precisely because a photocopier cannot reproduce them. The same trick used to prove a thing is real rather than to hide what it says.
Back to HIPS The microdot Hidden pixelsRead more elsewhere
Longer, harder and written for grown-ups. Worth a look when this page runs out.