A page from the Civil War diary
Recently we found a remarkable juxtaposition of Civil War history, math, and the Internet. Alison Weiss, a grad student in history at UC Berkeley, had the excellent idea to turn to the Internet to help with cracking the code used in a Civil War diary:
I’m a PhD student at U.C Berkeley. The history department recently got ahold of a Civil War diary, but a bunch of things are written in code. We can’t decipher it, so we were hoping someone in the public domain could. Anyone want to take a shot at deciphering this–or, also helpful, let me know what code you think it is?
People quickly jumped on the problem and made some progress*. A math grad student at Berkeley**, Qingchun Ren, figured out that it was substitution cypher with the the following substitutions:
The "Roseeta Stone"
And was able to decode sections of the diary using it:
Here is what the last page in the file (all written in code) reads:
Have never been quite so anxious for the mail.
Am really suffering to hear from Augusta.
All that ??? troubles me in now to break the news to Em.
It turns out, though, that the soldier is more clever then that. Different parts of the diary seem to use different cyphers. The entire diary is now available for download and Alison would welcome your help in reading the rest of the code! Go here for the full text.
* What did people do with all their free time before the Internet? Probably wasted it writing literature, curing diseases, and proving great theorems 
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** Amusingly, even though Alison and Qingchun are at the same university, they couldn’t help each other without first involving the rest of the world!
