Four of Hearts: Alice and Bob


I gave a note to Isaac meant for you,
but Marvin changed my message to a curse,
and though the barb that reached you wasn’t true,
you shivered at the harshness of my verse.

The next time I made sure to use a code,
So such a change would never fit the rhythm.
But Eve was smart, and understood my ode,
Her friends took part, and took our secret with ’em.

Embarrassed by such semaphore of hearts,
I used entangled light to write my note on.
But Eve still looked, and such a look imparts
an altered quantum state upon the photon.

To heχ with fears of stickybeaks or malice
Dear Bob, I’ll shout, I love you, signed, your Alice.


 

 

The fibre optic cables on this week’s card signify communication, and the name Alice in that context immediately brings to mind Alice and Bob, the characters most often used in explanations of cryptography. So I thought I might write something explaining cryptography. The letter of the week caused me to discover that there is a cipher named Q, so I figured I’d end up with a mnemonic rhyming poem explaining the Q algorithm, perhaps with something clever such as a rhyme scheme based on a message Q-encoded using the number 4 (of hearts) as a key. Alas, I never managed to find the original paper describing the algorithm, only one pointing out vulnerabilities in it. Even that, I could barely understand, as I’m not an expert on cryptography.

On Saturday evening I was getting a little desperate… deciding to write about ciphers is one thing, actually starting to do so is quite another. Then, some time after midnight, I came up with a line in blank verse, and I was away. By about 2:30 I had a pleasing first draft, with none of the rhythmic imperfections which plague last week’s poem. I like sonnets… most of my favourite poems that I’ve written are sonnets, though I’m not sure I’d count this one amongst them. It’s rather lacking in emotion, and the ending is abrupt.

I’ll try to translate it into geek for you. In the first quatrain, Alice sends a plaintext message through the internet, with Isaac being the internet service provider. Unfortunately, Marvin, a malicious attacker, altered the message and sent it on. I’ve never seen the names Isaac and Marvin mentioned in cryptography examples before, and I didn’t check the references of the Alice and Bob wikipedia article, so I don’t know whether they’re real or just vandalism, but they fit into the poem nicely enough.

In the second quatrain, Alice uses a cipher, perhaps Q, with some kind of hash so that Marvin couldn’t tamper with the message without being detected. Alas, while Bob gets the message intact, Eve the eavesdropper still manages to decode the message and tell everybody about it.

In the third quatrain, they use quantum cryptography, which allows them to detect whether Eve was listening in. But it turns out Eve never tires of eavesdropping, so she was always listening, and Alice was never able to send the message.

Finally, Alice decides that she doesn’t care who knows that she’s in love with Bob, so she posts it in plaintext somewhere public, with a digital signature to prove that it’s her. I think it sounds better if I conclude it with ‘love from Alice’, but then I don’t get to imply the use of a digital signature. Essentially this is like the second stanza, but without even an attempt to fend off Eve, and presumably Alice is being more direct about her feelings, adding to what Bob already found out in the second quatrain. Sometimes love makes people do crazy things.

I would have liked to fill this with clever puns and poetic conceit by gradually encoding the stanzas themselves, but there’s only so much I can manage early on a Sunday morning, and I wanted to have Sunday free to go jump in a lake. There are nonetheless a few clever things in this poem, which I will list here in order to ruin any pleasure you might have in finding them yourselves.

Firstly, each quatrain mentions poetry. Well, not quite. But if you think it would be clever if they did, just change the third stanza:

Embarrassed by such semaphore of hearts,
I used entangled light to write my sonnet
But Eve still looked, and such a look imparts
a tattle-tale quantum state upon it.

I preferred the photon/note on version myself, but I’m starting to lean toward this one now that I’ve actually written the fourth line of it. It wouldn’t work with a monosyllabic pronunciation of ‘tale’ though. Secondly, I managed to get ‘four of hearts’ in there, disguised as ‘semaphore of hearts’, which implies broadcasting an intimate message by a medium as public as semaphore.

The final clever thing is heχ, using the Greek letter chi. This will be read either as something resembling ‘heck’ with a throat infection, or hexadecimal, depending on whether you’re a Greek or a geek.

You might have noticed that for the last couple of weeks, my card photos have been slightly more yellowish. This is because I replaced my toilet photo studio light with a power-saving fluorescent one, which my camera did not automatically adjust for. I’m still learning to use my camera, and although it has many fancy features which I’m gradually discovering, I tend to keep it on auto most of the time. But the other week, the friend who recommended this camera to me (who also happens to cook great Israeli food) showed me how to adjust it for taking photos in cloudy settings. Today I noticed it also has a setting for fluorescent, so I tried that. It’s an improvement, although the photos now have a slightly pink cast. I still had the card from last week in place, so I re-took that picture before taking this week’s one. Now that I see them side by side, I think the pink is too obvious and I prefer the old version. Perhaps I should correct the colours in software until I learn how to use the camera properly.

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  1. #1 by Kathi on June 30, 2008 - 4:45 pm

    Your poem proofed to me that I am more of a Greek than a Geek ;-): I read Chi as the homeric “kh” sound.
    I am not so sure if the throat infection picture is quite right though, my Greek professor always gave it a lighter aspiration, but I guess Tyrolean Greeks would pronounce the way you describe it ;-).

    Like

  2. #2 by mtgordon on July 3, 2008 - 12:31 am

    I do like this. 🙂 Having taken a cryptography course, I caught at least some of the references (Alice, Bob, Eve), though Isaac brought someone else to mind. If I were to give him a letter, I’m sure he’d tear it to confetti, giggling all the while, and perhaps eating a few of the pieces, all without malice.

    I’m a geek, but I’m also a classics geek, and I’ve used LaTeX, all of which confuses the issue greatly. I saw the pronunciation as ambiguous, probably intentionally so, in a sort of quantum state, I suppose. Maybe that was the idea.

    I’m not sure whether I’ve mentioned this to you before, but you totally rock. 🙂

    Like

  3. #3 by Angela Brett on July 5, 2008 - 12:32 am

    Eχcellent, two people read it the Greek way, I thought most people (except Kathi) would read it as hex. 🙂 I know it’s not really so throat-infection-y, but I like saying that x is pronounced like y with a throat infection, ever since a Swiss German guy said something like that to me.

    It is intentionally ambiguous, though I didn’t think of the quantum state idea. From now on I’m going to pretend I did.

    mtgordon, your Isaac sounds like a very secure method of encryption. I only knew of Alice, Bob and Eve before I wrote this, I got the other two names from wikipedia, so I can forgive you for not knowing that your son is an ISP. Thanks for mentioning that I totally rock, though I don’t have much practice at reacting to such comments, so I might not do it well. I can’t decide whether to blush and look away, or panic because I have less than two days to write something else which rocks.

    Like

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