Fall 2014 /Code/


Stray Thoughts

This is surely a first, so (cue the trumpet fanfare) welcome to the first editor’s letter ever written in code.

Not all of it, of course—as you can tell from the simple fact that you’re reading this. But in an issue on the theme of “code,” in addition to articles about genetic code and computer code and decoding animal calls, there had to be something about the clandestine side of the word. But alas, try as I might, I was unable to unearth a single Pomona source for a story about ciphers. Which shouldn’t have surprised me, I suppose, since the world of cryptology is, by its very nature, a secretive one.

So to fill that void, please forgive me for offering this light-hearted tutorial on a subject I’ve found intriguing ever since my secret decoder ring childhood.

Each paragraph below demonstrates a different cipher, and—don’t say I didn’t warn you—the codes get progressively harder as they go along. There are instructions in each paragraph to help you translate the next, but if you want to play along, you’ll have to work for it.

We’ll start with one of the oldest and simplest of codes—the Caesar cipher, named for the great Roman himself, who used it in his letters. In this substitution cipher, each letter is replaced by another a fixed number of letters up or down the alphabet. Once you figure out that number, the rest is easy.

Ecguct ekrjgtu ctg ejknf’u rnca vq fgeqfg, dwv vjga ctg cnuq vjg dcuku qh eqorngz eqfgu nkmg vjg Xkpgig`tg ekrjgt, kp yjkej c yqtf rtqxkfgu vjg mga hqt ownvkrng Ecguct ekrjgtu kp c tqvcvkpi ugswgpeg. Vjg pgzv rctcitcrj, hqt gzcorng, wugu “CDE” cu kvu mga. Vjwu, vjg hktuv ngvvgt ku qpg ngvvgt qhh, vjg ugeqpf vyq qhh, vjg vjktf vjtgg qhh, vjgp dcem vq qpg, cpf uq qp.

Sfb Ugkdeb`qc tzq qgmrffq sm yd skapbzixajb, asq hl zqwmsmdqymgw, qgmpd yod dxlmrr jxrr tnpar. Red mkkw qqsix skapbzixajb bgmgco hq qgc “lmc-qhkb oya,” vffbf rrcp zl bmrfqc qdvq zq x jcv. Sm adalcc, vns ptzqqyzs red lrlcohaxk txksb nd bzae kcqsco hl qgc hdw (X dorzjp ycon; X bpsxkq 25) cqmj sfb dorhtxkcks jbsrbq gk sfb lcprydd. Yac 26 rl zlv mcdzrfuc odqrkr. Ffllqc poyzdq xmb mtlzssxsglm, uehae zpb ccidrbc gk qcxk alcca lcpryddq xmwtzw. Qgc hdw edpb hq qgc chpps nxqydqymg mc sffr jbsrbq.

Bm ggc’nw wfqp rhna wsk qcw gyla fx rm ucxknghjd sc ysogg mw b of. Zs hweykewceokaarl.

And with that, welcome to the wonderful world of code.


Stray Thoughts (decoded)

Here is the plain text of the three enciphered paragraphs in the Stray Thoughts:

[Caesar Cipher:]
Caesar ciphers are child’s play to decode, but they are also the basis of complex codes like the Vinegère cipher, in which a word provides the key for multiple Caesar ciphers in a rotating sequence. The next paragraph, for example, uses “ABC” as its key. Thus, the first letter is one letter off, the second two off, the third three off, then back to one, and so on.

[Vinegére Cipher:]
The Vinegère was thought to be unbreakable, but in cryptography, those are famous last words. The only truly unbreakable cipher is the “one-time pad,” which uses an entire text as a key. To decode, you subtract the numerical value of each letter in the key (A equals zero; Z equals 25) from the equivalent letter in the message. Add 26 to any negative  result. Ignore spaces and punctuation, which are deleted in real coded messages anyway. The key here is the first  paragraph of this letter.

[One-Time Pad Cipher:]
If you’ve come this far, you must be as intrigued by codes as I am. So congratulations.