British code breakers during World War II get a lot of credit, and rightfully so (Enigma code, natch), but what about British code creators? Cryptography goes both ways...

When discussing British code creators during World War II, one must begin with Leo Marks. He headed the office that created codes that supplied British agents throughout Nazi-occupied Europe. But Marks wasn't some bureaucrat; he was an expect code breaker and code maker himself, who created a new method of encryption:

Poetry.

To encrypt messages sent to agents, a cipher has to be used. But what does one select? As we know from internet password restrictions, you want something that is long, easy for you to recall, but hard for someone else to figure out. So: poetry.

But not just poetry, because a Nazi with a knowledge of English literature could go through works of the Shakespeare, Tennyson, Byron, et al, and find the selected poem. So Marks wrote his own poems that were easy to remember and, obviously, not known to the Nazis!

After the war, Marks became a screenwriter, penning the screenplay to "Peeping Tom", a movie about a serial killer who films his victims.

Should have stuck to poetry!