Operation
To encrypt a message, Alice rotates the disks to produce the plaintext message along one "row" of the stack of disks, and then selects another row as the ciphertext. To decrypt the message, Bob rotates the disks on his cylinder to produce the ciphertext along a row. It is handy if both Alice and Bob know the offset of the row, but not really necessary since Bob can simply look around the cylinder to find a row that makes sense.
For example, a simplified "toy" Bazeries cylinder using only ten disks might be organised as shown below, with each disk "unwrapped" into a line and each marked with a designating number:
| 1: | < ZWAXJGDLUBVIQHKYPNTCRMOSFE < |
| 2: | < KPBELNACZDTRXMJQOYHGVSFUWI < |
| 3: | < BDMAIZVRNSJUWFHTEQGYXPLOCK < |
| 4: | < RPLNDVHGFCUKTEBSXQYIZMJWAO < |
| 5: | < IHFRLABEUOTSGJVDKCPMNZQWXY < |
| 6: | < AMKGHIWPNYCJBFZDRUSLOQXVET < |
| 7: | < GWTHSPYBXIZULVKMRAFDCEONJQ < |
| 8: | < NOZUTWDCVRJLXKISEFAPMYGHBQ < |
| 9: | < XPLTDSRFHENYVUBMCQWAOIKZGJ < |
| 10: | < UDNAJFBOWTGVRSCZQKELMXYIHP < |
If the "key", the sequence of disks, for this Bazeries cylinder is
- 7,9,5,10,1,6,3,8,2,4
and Alice wants to send the message "retreat now" to Bob, she rearranges the disks as per the key and rotates each disk to obtain the plaintext, which is shown at the left, with spacing added for clarity:
| 7: | < R AFDCE O NJQGWTHSPYBXIZULVKM < |
| 9: | < E NYVUB M CQWAOIKZGJXPLTDSRFH < |
| 5: | < T SGJVD K CPMNZQWXYIHFRLABEUO < |
| 10: | < R SCZQK E LMXYIHPUDNAJFBOWTGV < |
| 1: | < E ZWAXJ G DLUBVIQHKYPNTCRMOSF < |
| 6: | < A MKGHI W PNYCJBFZDRUSLOQXVET < |
| 3: | < T EQGYX P LOCKBDMAIZVRNSJUWFH < |
| 8: | < N OZUTW D CVRJLXKISEFAPMYGHBQ < |
| 2: | < O YHGVS F UWIKPBELNACZDTRXMJQ < |
| 4: | < W AORPL N DVHGFCUKTEBSXQYIZMJ < |
She then selects the ciphertext from the sixth row of the cylinder up from the plaintext. This ciphertext is also highlighted above with spacing, and gives:
- OMKEGWPDFN
When Bob gets the ciphertext, he rearranges the disks on his cylinder to the key arrangement, rotates the disks to give the ciphertext, and then reads the plaintext six rows down from the ciphertext, or simply looks over the cylinder for a row that makes sense.
Read more about this topic: Jefferson Disk
Famous quotes containing the word operation:
“You may read any quantity of books, and you may almost as ignorant as you were at starting, if you don’t have, at the back of your minds, the change for words in definite images which can only be acquired through the operation of your observing faculties on the phenomena of nature.”
—Thomas Henry Huxley (1825–95)
“An absolute can only be given in an intuition, while all the rest has to do with analysis. We call intuition here the sympathy by which one is transported into the interior of an object in order to coincide with what there is unique and consequently inexpressible in it. Analysis, on the contrary, is the operation which reduces the object to elements already known.”
—Henri Bergson (1859–1941)