The Network by Jason Elliot

was a pagan.’
    The smile fades. He’s not really expecting this and a slight stutter comes into his voice. ‘But … but do you believe your actions in this life make a difference in the world to come?’
    ‘If we’re going to be judged on something in an afterlife, I think it’ll probably be our inactions . It’s not difficult to live a pious life, if you think about it, imagining you’ll be saved if you stick to a few rules. But think of all the good things you could have done but didn’t because you were too lazy or complacent. I think we’ll be judged on our potential.’
    He’s frowning now.
    ‘I forget where I first heard the idea, but it does stay with you. I think it’s somewhere in the Qur’an.’
    I pluck a copy of the Watchtower from his grasp and thank him warmly, saying I hope I’ll see him again soon. The speed at which he walks away up the drive suggests I won’t.
    With a feeling of guilty victory I return to my coffee. Then I close the windows in the sitting room because the light is hurting my eyes, and sit down at the table, taking the postcard from the mantelpiece where I left it. I read it again several times. There’s nothing out of the ordinary about the text. I wonder if the picture, depicting a nomad leading a line of camels, is intended to convey a meaning. It’s the identity of ‘Mohammed’ that bothers me. I wonder if it might be worth looking through my diaries from the period I was last in Kabul, but if the card was sent months earlier, whoever Mohammed is will have given up hearing from me.
    I take the card to the kitchen and boil the kettle, hold the card in the steam and gently work a corner of the stamp with the tip of a knife. I’m not sure what to expect – anything strange or out of the ordinary.
    As the stamp begins to curl back in the steam, what I see is even stranger. Under the stamp, in the same ink as the writing on the card, is a tiny drawing of a dinosaur with a smiling face.
    It’s a stegosaurus.
     
    Cryptography is the science of hiding the true meaning of a message by disguising it; encrypting it by some means known to the recipient but not to others. As long as the sender and the recipient keep their means of encryption secret, the effort needed by the codebreaker is determined by the difficulty of the code. Some codes, like alphabetical substitutions, are easy to crack because the frequencies at which letters appear in words are well known. Others, like one-time pads based on random numbers, can only be cracked by computers, if at all. The most complex codes that use block ciphers and multiple algorithms need both computers and time, and modern computing power means that few codes are truly impossible to crack, given enough of the latter. But the science of hiding a message by disguising it as something which on the surface appears innocent is called steganography.
    Strictly speaking, a message written in invisible ink across an ordinary letter is an example of steganography: the visible or cover message is innocuous. It’s an ancient idea. Herodotus describes a king who tattooed a secret message on the shaven head of his slave, whose hair was allowed to grow before he travelled through enemy territory to deliver it. More recent applications allow secret text to be hidden in the data of digitised photographs sent over the Internet. The advantage of a steganographic message is that, unlike a coded message, the secret part doesn’t attract attention to itself. It resembles something ordinary, and hides itself thereby.
    My ex-wife, come to think of it, has a steganographic personality: an innocent-looking face concealing a cruel agenda.
    I decide it has to be the numbers: thirteen and forty. ‘Degrees’ in the cover message also seems to be an overt clue. I find an atlas and look up the latitude and longitude. Problem. Thirteen degrees north and forty degrees east puts me in the mountains of northern Ethiopia. Forty degrees west is equally challenging