Every Resistance organization had worries about security. They were particularly acute for groups like Dutch-Paris that simply could not be kept among friends. Dutch-Paris was too big and covered too much territory. Sometimes contact had to be made between strangers, although both strangers would come recommended and vouched for by mutually known third parties. One way to make sure you were meeting the right stranger was passwords.

Passwords work best if they are random enough to be unguessable. For instance, in 1943 John Weidner met a Dutch friend in a café in Brussels. He gave him an envelope and asked him to deliver it to his father in The Hague. Weidner didn’t have a password worked out with his father, but he wanted his father to know that he could trust the stranger knocking on his door claiming to know his son. So he told the friend to use this word: “postzegel” [postage stamp]. The friend had no idea why “postzegel”, but it worked with Weidner senior. Father and son collected postage stamps together and Weidner sometimes sent them to his father during the war in place of money, thinking that his father could sell the stamps for cash.

You could also use layers of passwords. For example, Weidner had an appointment with a Dutch student in a café in Louvain, Belgium, in April 1944. If the Dutch student didn’t show up, Weidner had a back-up address with a different Dutchman he’d never met. In this case, Weidner was to say “1918” and the Dutchman was to reply “1944”. That one was near and dear to the Dutchmen’s hearts of course, but a clever German could have easily figured it out. The First World War ended in 1918 with a victory for the Allies; the Dutchmen hoped the Second would end in 1944 with the same victors.

So they had a second layer of far more random passwords: 1) Société des Nations [League of Nations] 2) Jura [mountains on the Franco-Swiss border] and 3) Statue de J-J Rousseau [statue of Jean-Jacque Rousseau]. That series was probably thought up by a philosophy student, but what their meaning was for the three men involved eludes me and most probably any lurking Gestapo agents.

On occasion, however, words wouldn’t work. In February 1944 Weidner and a contact with the Dutch authorities in Spain made an arrangement that couriers coming from Spain would leave letters with Weidner’s sister in Paris. The pass sign would be an envelope that was lightly ripped along the top edge.